All Publications

@article{pmid36913480,

title = {Acute Quark Ingestion Increases Muscle Protein Synthesis Rates at Rest with a Further Increase after Exercise in Young and Older Adult Males in a Parallel-Group Intervention Trial},

author = {Wesley Jh Hermans and Cas J Fuchs and Jean Nyakayiru and Floris K Hendriks and Lisanne Hp Houben and Joan M Senden and Luc Jc Loon and Lex B Verdijk},

doi = {10.1016/j.tjnut.2022.10.003},

issn = {1541-6100},

year  = {2023},

date = {2023-01-01},

journal = {The Journal of nutrition},

volume = {153},

number = {1},

pages = {66–75},

abstract = {BACKGROUND: Ingestion of protein concentrates or isolates increases muscle protein synthesis rates in young and older adults. There is far less information available on the anabolic response following the ingestion of dairy wholefoods, which are commonly consumed in a normal diet.nnOBJECTIVES: This study investigates whether ingestion of 30 g protein provided as quark increases muscle protein synthesis rates at rest and whether muscle protein synthesis rates are further increased after resistance exercise in young and older adult males.nnMETHODS: In this parallel-group intervention trial, 14 young (18-35 y) and 15 older (65-85 y) adult males ingested 30 g protein provided as quark after a single-legged bout of resistance exercise on leg press and leg extension machines. Primed, continuous intravenous L-[ring-C]-phenylalanine infusions were combined with the collection of blood and muscle tissue samples to assess postabsorptive and 4-h postprandial muscle protein synthesis rates at rest and during recovery from exercise. Data represent means ± SDs; η was used to measure the effect size.nnRESULTS: Plasma total amino acid and leucine concentrations increased after quark ingestion in both groups (both time: P ¡ 0.001; η ¿ 0.8), with no differences between groups (time × group: P = 0.127 and P = 0.172, respectively; η¡0.1). Muscle protein synthesis rates increased following quark ingestion at rest in both young (from 0.030 ± 0.011 to 0.051 ± 0.011 %$cdot$h) and older adult males (from 0.036 ± 0.011 to 0.062 ± 0.013 %$cdot$h), with a further increase in the exercised leg (to 0.071 ± 0.023 %$cdot$h and to 0.078 ± 0.019 %$cdot$h, respectively; condition: P ¡ 0.001; η = 0.716), with no differences between groups (condition × group: P = 0.747; η = 0.011).nnCONCLUSIONS: Quark ingestion increases muscle protein synthesis rates at rest with a further increase following exercise in both young and older adult males. The postprandial muscle protein synthetic response following quark ingestion does not differ between healthy young and older adult males when an ample amount of protein is ingested. This trial was registered at the Dutch Trial register, which is accessible via trialsearch.who.int www.trialregister.nl as NL8403.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid37154183,

title = {Energy Expenditure, Body Composition, and Skeletal Muscle Oxidative Capacity in Patients with Myotonic Dystrophy Type 1},

author = {Isis B T Joosten and Cas J Fuchs and Milou Beelen and Guy Plasqui and Luc J C Loon and Catharina G Faber},

doi = {10.3233/JND-230036},

issn = {2214-3602},

year  = {2023},

date = {2023-01-01},

journal = {Journal of neuromuscular diseases},

volume = {10},

number = {4},

pages = {701–712},

abstract = {BACKGROUND: Myotonic dystrophy type 1 (DM1) patients are at risk for metabolic abnormalities and commonly experience overweight and obesity. Possibly, weight issues result from lowered resting energy expenditure (EE) and impaired muscle oxidative metabolism.nnOBJECTIVES: This study aims to assess EE, body composition, and muscle oxidative capacity in patients with DM1 compared to age-, sex- and BMI-matched controls.nnMETHODS: A prospective case control study was conducted including 15 DM1 patients and 15 matched controls. Participants underwent state-of-the-art methodologies including 24 h whole room calorimetry, doubly labeled water and accelerometer analysis under 15-days of free-living conditions, muscle biopsy, full body magnetic resonance imaging (MRI), dual-energy x-ray absorptiometry (DEXA), computed tomography (CT) upper leg, and cardiopulmonary exercise testing.nnRESULTS: Fat ratio determined by full body MRI was significantly higher in DM1 patients (56 [49-62] %) compared to healthy controls (44 [37-52] % ; p = 0.027). Resting EE did not differ between groups (1948 [1742-2146] vs (2001 [1853-2425¿] kcal/24 h, respectively; p = 0.466). In contrast, total EE was 23% lower in DM1 patients (2162 [1794-2494] vs 2814 [2424-3310] kcal/24 h; p = 0.027). Also, DM1 patients had 63% less steps (3090 [2263-5063] vs 8283 [6855-11485] steps/24 h; p = 0.003) and a significantly lower VO2 peak (22 [17-24] vs 33 [26-39] mL/min/kg; p = 0.003) compared to the healthy controls. Muscle biopsy citrate synthase activity did not differ between groups (15.4 [13.3-20.0] vs 20.1 [16.6-25.8] μM/g/min, respectively; p = 0.449).nnCONCLUSIONS: Resting EE does not differ between DM1 patients and healthy, matched controls when assessed under standardized circumstances. However, under free living conditions, total EE is substantially reduced in DM1 patients due to a lower physical activity level. The sedentary lifestyle of DM1 patients seems responsible for the undesirable changes in body composition and aerobic capacity.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid36374263,

title = {Twist2-Expressing Cells Reside in Human Skeletal Muscle and Are Responsive to Aging and Resistance Exercise Training},

author = {Nick Gaulton and Griffen Wakelin and Laura V Young and Scott Wotherspoon and Michael Kamal and Gianni Parise and Joshua P Nederveen and Andy Holwerda and Lex B Verdijk and Luc J C Loon and Tim Snijders and Adam P Johnston},

doi = {10.1096/fj.202201349RR},

issn = {1530-6860},

year  = {2022},

date = {2022-12-01},

journal = {The FASEB journal : official publication of the Federation of American Societies for Experimental Biology},

volume = {36},

number = {12},

pages = {e22642},

abstract = {Skeletal muscle is maintained and repaired by sub-laminar, Pax7-expressing satellite cells. However, recent mouse investigations have described a second myogenic progenitor population that resides within the myofiber interstitium and expresses the transcription factor Twist2. Twist2-expressing cells exclusively repair and maintain type IIx/b muscle fibers. Currently, it is unknown if Twist2-expressing cells are present in human skeletal muscle and if they function as myogenic progenitors. Here, we perform a combination of single-cell RNA sequencing analysis and immunofluorescence staining to demonstrate the identity and localization of Twist2-expressing cells in human skeletal muscle. Twist2-expressing cells were identified to be anatomically and transcriptionally comparable to fibro-adipogenic progenitors (FAPs) and lack expression of typical satellite cell markers such as Pax7. Comparative analysis revealed that human and mouse Twist2-expressing cells were highly transcriptionally analogous and resided within the same anatomical structures in vivo. Examination of young and aged skeletal muscle biopsy samples revealed that Twist2-positive cells are more prevalent in aged muscle and increase following 12-weeks of resistance exercise training (RET) in humans. However, the quantity of Twist2-positive cells was not correlated with indices of muscle mass or muscle fiber cross-sectional area (CSA) in young or older muscle, and their abundance was surprisingly, negatively correlated with CSA and myonuclear domain size following RET. Taken together, we have identified cells expressing Twist2 in human skeletal muscle which are responsive to aging and exercise. Further examination of their myogenic potential is warranted.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid36774104,

title = {Raw Eggs to Support Postexercise Recovery in Healthy Young Men: Did Rocky Get It Right or Wrong?},

author = {Cas J Fuchs and Wesley Jh Hermans and Joey Sj Smeets and Joan M Senden and Janneau Kranenburg and Stefan Hm Gorissen and Nicholas A Burd and Lex B Verdijk and Luc Jc Loon},

doi = {10.1093/jn/nxac174},

issn = {1541-6100},

year  = {2022},

date = {2022-11-01},

journal = {The Journal of nutrition},

volume = {152},

number = {11},

pages = {2376–2386},

abstract = {BACKGROUND: Egg protein is ingested during recovery from exercise to facilitate the postexercise increase in muscle protein synthesis rates and, as such, to support the skeletal muscle adaptive response to exercise training. The impact of cooking egg protein on postexercise muscle protein synthesis is unknown.nnOBJECTIVES: We sought to compare the impact of ingesting unboiled (raw) compared with boiled eggs during postexercise recovery on postprandial myofibrillar protein synthesis rates.nnMETHODS: In a parallel design, 45 healthy, resistance-trained young men (age: 24 y; 95% CI: 23, 25 y) were randomly assigned to ingest 5 raw eggs ($sim$30 g protein), 5 boiled eggs ($sim$30 g protein), or a control breakfast ($sim$5 g protein) during recovery from a single session of whole-body resistance-type exercise. Primed continuous l-[ring-C]-phenylalanine infusions were applied, with frequent blood sampling. Muscle biopsies were collected immediately after cessation of resistance exercise and at 2 and 5 h into the postexercise recovery period. Primary (myofibrillar protein synthesis rates) and secondary (plasma amino acid concentrations) outcomes were analyzed using repeated-measures (time × group) ANOVA.nnRESULTS: Ingestion of eggs significantly increased plasma essential amino acid (EAA) concentrations, with 20% higher peak concentrations following ingestion of boiled compared with raw eggs (time × group: P ¡ 0.001). Myofibrillar protein synthesis rates were significantly increased during the postexercise period when compared with basal, postabsorptive values in all groups (2-4-fold increase: P ¡ 0.001). Postprandial myofibrillar protein synthesis rates were 20% higher after ingesting raw eggs [0.067%/h; 95% CI: 0.056, 0.077%/h; effect size (Cohen d): 0.63], and 18% higher after ingesting boiled eggs (0.065%/h; 95% CI: 0.058, 0.073%/h; effect size: 0.69) when compared with the control breakfast (0.056%/h; 95% CI: 0.048, 0.063%/h), with no significant differences between groups (time × group: P = 0.077).nnCONCLUSIONS: The ingestion of raw, as opposed to boiled, eggs attenuates the postprandial rise in circulating EAA concentrations. However, postexercise muscle protein synthesis rates do not differ after ingestion of 5 raw compared with 5 boiled eggs in healthy young men. This trial was registered at the Nederlands Trial Register as NL6506 (www.trialregister.nl).},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid35438672,

title = {Potato Protein Ingestion Increases Muscle Protein Synthesis Rates at Rest and during Recovery from Exercise in Humans},

author = {Philippe J M Pinckaers and Floris K Hendriks and Wesley J H Hermans and Joy P B Goessens and Joan M Senden and Janneau M X VAN Kranenburg and Will K H W Wodzig and Tim Snijders and Luc J C VAN Loon},

doi = {10.1249/MSS.0000000000002937},

issn = {1530-0315},

year  = {2022},

date = {2022-09-01},

journal = {Medicine and science in sports and exercise},

volume = {54},

number = {9},

pages = {1572–1581},

abstract = {INTRODUCTION: Plant-derived proteins have received considerable attention as an alternative to animal-based proteins and are now frequently used in both plant-based diets and sports nutrition products. However, little information is available on the anabolic properties of potato-derived protein. This study compares muscle protein synthesis rates after the ingestion of 30 g potato protein versus 30 g milk protein at rest and during recovery from a single bout of resistance exercise in healthy, young males.nnMETHODS: In a randomized, double-blind, parallel-group design, 24 healthy young males (24 ± 4 yr) received primed continuous l -[ ring - 13 C 6 ]-phenylalanine infusions while ingesting 30 g potato-derived protein or 30 g milk protein after a single bout of unilateral resistance exercise. Blood and muscle biopsies were collected for 5 h after protein ingestion to assess postprandial plasma amino acid profiles and mixed muscle protein synthesis rates at rest and during recovery from exercise.nnRESULTS: Ingestion of both potato and milk protein increased mixed muscle protein synthesis rates when compared with basal postabsorptive values (from 0.020% ± 0.011% to 0.053% ± 0.017%$cdot$h -1 and from 0.021% ± 0.014% to 0.050% ± 0.012%$cdot$h -1 , respectively; P ¡ 0.001), with no differences between treatments ( P = 0.54). In the exercised leg, mixed muscle protein synthesis rates increased to 0.069% ± 0.019% and 0.064% ± 0.015%$cdot$h -1 after ingesting potato and milk protein, respectively ( P ¡ 0.001), with no differences between treatments ( P = 0.52). The muscle protein synthetic response was greater in the exercised compared with the resting leg ( P ¡ 0.05).nnCONCLUSIONS: Ingestion of 30 g potato protein concentrate increases muscle protein synthesis rates at rest and during recovery from exercise in healthy, young males. Muscle protein synthesis rates after the ingestion of 30 g potato protein do not differ from rates observed after ingesting an equivalent amount of milk protein.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid35584344,

title = {Muscle Protein Synthesis after Protein Administration in Critical Illness},

author = {Lee-Anne S Chapple and Imre W K Kouw and Matthew J Summers and Luke M Weinel and Samuel Gluck and Eamon Raith and Peter Slobodian and Stijn Soenen and Adam M Deane and Luc J C Loon and Marianne J Chapman},

doi = {10.1164/rccm.202112-2780OC},

issn = {1535-4970},

year  = {2022},

date = {2022-09-01},

journal = {American journal of respiratory and critical care medicine},

volume = {206},

number = {6},

pages = {740–749},

abstract = {Dietary protein may attenuate the muscle atrophy experienced by patients in the ICU, yet protein handling is poorly understood. To quantify protein digestion and amino acid absorption and fasting and postprandial myofibrillar protein synthesis during critical illness. Fifteen mechanically ventilated adults (12 male; aged 50 ± 17 yr; body mass index, 27 ± 5 kg$cdot$m) and 10 healthy control subjects (6 male; 54 ± 23 yr; body mass index, 27 ± 4 kg$cdot$m) received a primed intravenous L-[ring-H]-phenylalanine, L-[3,5-H]-tyrosine, and L-[1-C]-leucine infusion over 9.5 hours and a duodenal bolus of intrinsically labeled (L-[1-C]-phenylalanine and L-[1-C]-leucine) intact milk protein (20 g protein) over 60 minutes. Arterial blood and muscle samples were taken at baseline (fasting) and for 6 hours following duodenal protein administration. Data are mean ± SD, analyzed with two-way repeated measures ANOVA and independent samples test. Fasting myofibrillar protein synthesis rates did not differ between ICU patients and healthy control subjects (0.023 ± 0.013% h vs. 0.034 ± 0.016% h; = 0.077). After protein administration, plasma amino acid availability did not differ between groups (ICU patients, 54.2 ± 9.1%, vs. healthy control subjects, 61.8 ± 13.1%; = 0.12), and myofibrillar protein synthesis rates increased in both groups (0.028 ± 0.010% h vs. 0.043 ± 0.018% h; main time effect = 0.046; -interaction = 0.584) with lower rates in ICU patients than in healthy control subjects (main group effect = 0.001). Incorporation of protein-derived phenylalanine into myofibrillar protein was $sim$60% lower in ICU patients (0.007 ± 0.007 mol percent excess vs. 0.017 ± 0.009 mol percent excess; = 0.007). The capacity for critically ill patients to use ingested protein for muscle protein synthesis is markedly blunted despite relatively normal protein digestion and amino acid absorption.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid35686720,

title = {Nutritional Strategies to Attenuate Postprandial Glycemic Response},

author = {Kenneth Pasmans and Ruth C R Meex and Luc J C Loon and Ellen E Blaak},

doi = {10.1111/obr.13486},

issn = {1467-789X},

year  = {2022},

date = {2022-09-01},

journal = {Obesity reviews : an official journal of the International Association for the Study of Obesity},

volume = {23},

number = {9},

pages = {e13486},

abstract = {Maintaining good glycemic control to prevent complications is crucial in people with type 2 diabetes and in people with prediabetes and in the general population. Different strategies to improve glycemic control involve the prescription of blood glucose-lowering drugs and the modulation of physical activity and diet. Interestingly, lifestyle intervention may be more effective in lowering hyperglycemia than pharmaceutical intervention. Regulation of postprandial glycemia is complex, but specific nutritional strategies can be applied to attenuate postprandial hyperglycemia. These strategies include reducing total carbohydrate intake, consuming carbohydrates with a lower glycemic index, the addition of or substitution by sweeteners and fibers, using food compounds which delay or inhibit gastric emptying or carbohydrate digestion, and using food compounds which inhibit intestinal glucose absorption. Nevertheless, it must be noted that every individual may respond differently to certain nutritional interventions. Therefore, a personalized approach is of importance to choose the optimal nutritional strategy to improve postprandial glycemia for each individual, but this requires a better understanding of the mechanisms explaining the differential responses between individuals.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{philippej.m.pinckaers2022,

title = {The Muscle Protein Synthetic Response to the Ingestion of a Plant-Derived Protein Blend Does Not Differ from an Equivalent Amount of Milk Protein in Healthy, Young Males},

author = {Philippe J. M. Pinckaers and Imre W. K. Kouw and Stefan H. M. Gorissen and Stefan H. M. Gorissen and Lisanne H P Houben and Joan M. Senden and Joan M. G. Senden and Will K. W. H. Wodzig and Lisette C. P. G. M. Groot and Lex B. Verdijk and Tim Snijders and Luc J. C. Loon},

doi = {10.1093/jn/nxac222},

year  = {2022},

date = {2022-09-01},

urldate = {2022-09-01},

journal = {Journal of Nutrition},

volume = {152},

issue = {12},

pages = {2734-2743},

abstract = {Abstract Background Plant-derived proteins are considered to have lesser anabolic properties when compared with animal-derived proteins. The attenuated rise in muscle protein synthesis rates following ingestion of plant compared with animal-derived protein has been, at least partly, attributed to deficiencies in specific amino acids such as leucine, lysine, and/or methionine. Combining different plant-derived proteins may provide plant-derived protein blends with a more balanced amino acid profile. Objective This study aimed to compare post-prandial muscle protein synthesis rates following the ingestion of 30 g milk protein with a 30 g blend combining wheat, corn, and pea protein in healthy, young males. Design In a randomized, double blind, parallel-group design, 24 young males (24 ± 4 y) received a primed continuous L-[ring-13C6]-phenylalanine infusion after which they ingested 30 g milk protein (MILK) or a 30 g plant-derived protein blend combining 15 g wheat, 7.5 g corn, and 7.5 g pea protein (PLANT-BLEND). Blood and muscle biopsies were collected frequently for 5 h to assess post-prandial plasma amino acid profiles (secondary outcome) and subsequent muscle protein synthesis rates (primary outcome). Data were analyzed by two way-repeated measures ANOVA and two-samples t-tests. Results MILK increased plasma essential amino acid concentrations more than PLANT-BLEND over the 5 h postprandial period (incremental area under curve 151±31 vs 79 ± 12 mmol$bullet$300 min$bullet$L-1 respectively; P < 0.001). Ingestion of both MILK and PLANT-BLEND increased myofibrillar protein synthesis rates (P < 0.001), with no significant differences between treatments (0.053 ± 0.013 and 0.064 ± 0.016%$bullet$h-1, respectively; P = 0.08) Conclusion Ingestion of 30 g of a plant-derived protein blend combining wheat, corn, and pea-derived protein increases muscle protein synthesis rates in healthy, young males. The muscle protein synthetic response to the ingestion of 30 g of this plant-derived protein blend does not differ from the ingestion of an equivalent amount of a high quality animal-derived protein. Clinical Trial Registry number: Nederlands Trial Register: NTR6548 https://www.trialregister.nl/},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid35732003,

title = {Dietary Nitrate Increases Submaximal SERCA Activity and ADP Transfer to Mitochondria in Slow-Twitch Muscle of Female Mice},

author = {Heather L Petrick and Stuart Brownell and Bayley Vachon and Henver S Brunetta and Rachel M Handy and Luc J C Loon and Coral L Murrant and Graham P Holloway},

doi = {10.1152/ajpendo.00371.2021},

issn = {1522-1555},

year  = {2022},

date = {2022-08-01},

journal = {American journal of physiology. Endocrinology and metabolism},

volume = {323},

number = {2},

pages = {E171–E184},

abstract = {Rapid oscillations in cytosolic calcium (Ca) coordinate muscle contraction, relaxation, and physical movement. Intriguingly, dietary nitrate decreases ATP cost of contraction, increases force production, and increases cytosolic Ca, which would seemingly necessitate a greater demand for sarcoplasmic reticulum Ca ATPase (SERCA) to sequester Ca within the sarcoplasmic reticulum (SR) during relaxation. As SERCA is highly regulated, we aimed to determine the effect of 7-day nitrate supplementation (1 mM via drinking water) on SERCA enzymatic properties and the functional interaction between SERCA and mitochondrial oxidative phosphorylation. In soleus, we report that dietary nitrate increased force production across all stimulation frequencies tested, and throughout a 25 min fatigue protocol. Mice supplemented with nitrate also displayed an $sim$25% increase in submaximal SERCA activity and SERCA efficiency ( = 0.053) in the soleus. To examine a possible link between ATP consumption and production, we established a methodology coupling SERCA and mitochondria in permeabilized muscle fibers. The premise of this experiment is that the addition of Ca in the presence of ATP generates ADP from SERCA to support mitochondrial respiration. Similar to submaximal SERCA activity, mitochondrial respiration supported by SERCA-derived ADP was increased by $sim$20% following nitrate in red gastrocnemius. This effect was fully attenuated by the SERCA inhibitor cyclopiazonic acid and was not attributed to differences in mitochondrial oxidative capacity, ADP sensitivity, protein content, or reactive oxygen species emission. Overall, these findings suggest that improvements in submaximal SERCA kinetics may contribute to the effects of nitrate on force production during fatigue. We show that nitrate supplementation increased force production during fatigue and increased submaximal SERCA activity. This was also evident regarding the high-energy phosphate transfer from SERCA to mitochondria, as nitrate increased mitochondrial respiration supported by SERCA-derived ADP. Surprisingly, these observations were only apparent in muscle primarily expressing type I (soleus) but not type II fibers (EDL). These findings suggest that alterations in SERCA properties are a possible mechanism in which nitrate increases force during fatiguing contractions.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Stevens2022,

title = {Skeletal Muscles of Patients Infected with SARS-CoV-2 Develop Severe Myofiber Damage upon One Week of Admission on the Intensive Care Unit},

author = {Sjoerd Stevens and Paul Hendrickx and Tim Snijders and Ivo Lambrichts and Björn Stessel and Jasperina Dubois and Luc J. C. Loon and Frank Vandenabeele and Anouk Agten},

doi = {10.3390/app12147310},

issn = {2076-3417},

year  = {2022},

date = {2022-07-00},

journal = {Applied Sciences},

volume = {12},

number = {14},

publisher = {MDPI AG},

abstract = {¡jats:p¿Many critically ill patients infected with SARS-CoV-2 have been submitted to an intensive care unit (ICU). Patients with a SARS-CoV-2 infection that survive critical illness are confronted with months of physical impairments. To maximize recovery, it is important to understand the musculoskeletal involvement in critically ill patients infected with SARS-CoV-2. The aim of the present study was to assess the myocellular changes in SARS-CoV-2 patients that occur throughout the first week of ICU admission. In n = 22 critically ill patients infected with SARS-CoV-2, a biopsy sample from the vastus lateralis muscle was obtained at day 1–3 and day 5–8 following ICU admission. Fluorescence microscopy was used to assess type I and type II muscle fiber size and distribution, myonuclear content, and muscle tissue capillarization. Transmission electron microscopy was used to support quantitative data at an ultrastructural level. Changes in type I and type II muscle fiber size showed large inter-individual variation. The average change in type I fiber size was +309 ± 1834 µm2, ranging from -2129 µm2 (-31%) to +3375 µm2 (+73%). The average change in type II fiber size was -224 ± 1256 µm2, ranging from -1410 µm2 (-36%) to +2592 µm2 (+48%). Ultrastructural observations showed myofibrillar and hydropic degeneration, and fiber necrosis. This study shows that ICU patients admitted with SARS-CoV-2 suffer from substantial muscle fiber damage during ICU admission. These results are a call for action towards more specialized rehabilitation programs for patients admitted to the ICU with SARS-CoV-2 infection.¡/jats:p¿},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Stevens2022b,

title = {Skeletal Muscle Fibre Characteristics of the Lumbar Multifidus Muscle in Patients Undergoing Microdiscectomy for Unilateral Lumbar Disc Herniation},

author = {S. Stevens and A. Agten and T. Snijders and M. Plazier and S. Bamps and T. Assieker and M. W. Betz and A. Timmermans and L. J. C. Loon and F. Vandenabeele},

doi = {10.32098/mltj.03.2022.19},

issn = {2240-4554},

year  = {2022},

date = {2022-07-00},

journal = {Muscle Ligaments and Tendons J},

volume = {12},

number = {03},

publisher = {Edra SpA},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid35108354,

title = {Perspective: Vegan Diets for Older Adults? A Perspective on the Potential Impact on Muscle Mass and Strength},

author = {Jacintha Domić and Pol Grootswagers and Luc J C Loon and Lisette C P G M Groot},

doi = {10.1093/advances/nmac009},

issn = {2156-5376},

year  = {2022},

date = {2022-06-01},

journal = {Advances in nutrition (Bethesda, Md.)},

volume = {13},

number = {3},

pages = {712–725},

abstract = {Consumers are increasingly encouraged to consume more plant-based foods and lower their consumption of foods from animal origin. Concurrently, older adults are recommended to consume an adequate amount of high-quality dietary protein for the prevention of age-related muscle loss. In the current Perspective article, we discuss why it may not be preferred to consume a vegan diet at an older age. Our perspective is based on the proposed lower bioavailability and functionality of proteins in a vegan diet due to the matrix of the whole-food protein sources, the lower essential amino acid (EAA) content, and specific EAA deficiencies in proteins derived from plant-based foods. We propose that a vegan diet increases the risk of an inadequate protein intake at an older age and that current strategies to improve the anabolic properties of plant-based foods are not feasible for many older adults. We provide recommendations for further research to substantiate the remaining knowledge gaps regarding the consequences of a vegan diet on skeletal muscle mass and strength at an older age.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid34605901,

title = {The Impact of Collagen Protein Ingestion on Musculoskeletal Connective Tissue Remodeling: A Narrative Review},

author = {Andrew M Holwerda and Luc J C Loon},

doi = {10.1093/nutrit/nuab083},

issn = {1753-4887},

year  = {2022},

date = {2022-05-01},

journal = {Nutrition reviews},

volume = {80},

number = {6},

pages = {1497–1514},

abstract = {Collagen is the central structural component of extracellular connective tissue, which provides elastic qualities to tissues. For skeletal muscle, extracellular connective tissue transmits contractile force to the tendons and bones. Connective tissue proteins are in a constant state of remodeling and have been shown to express a high level of plasticity. Dietary-protein ingestion increases muscle protein synthesis rates. High-quality, rapidly digestible proteins are generally considered the preferred protein source to maximally stimulate myofibrillar (contractile) protein synthesis rates. In contrast, recent evidence demonstrates that protein ingestion does not increase muscle connective tissue protein synthesis. The absence of an increase in muscle connective tissue protein synthesis after protein ingestion may be explained by insufficient provision of glycine and/or proline. Dietary collagen contains large amounts of glycine and proline and, therefore, has been proposed to provide the precursors required to facilitate connective tissue protein synthesis. This literature review provides a comprehensive evaluation of the current knowledge on the proposed benefits of dietary collagen consumption to stimulate connective tissue remodeling to improve health and functional performance.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid35118634,

title = {Exercise-Based Interventions to Counteract Skeletal Muscle Mass Loss in People with Cancer: Can We Overcome the Odds?},

author = {Kelcey A Bland and Imre W K Kouw and Luc J C Loon and Eva M Zopf and Ciaran M Fairman},

doi = {10.1007/s40279-021-01638-z},

issn = {1179-2035},

year  = {2022},

date = {2022-05-01},

journal = {Sports medicine (Auckland, N.Z.)},

volume = {52},

number = {5},

pages = {1009–1027},

abstract = {Addressing skeletal muscle mass loss is an important focus in oncology research to improve clinical outcomes, including cancer treatment tolerability and survival. Exercise is likely a necessary component of muscle-mass-preserving interventions for people with cancer. However, randomized controlled trials with exercise that include people with cancer with increased susceptibility to more rapid and severe muscle mass loss are limited. The aim of the current review is to highlight features of cancer-related skeletal muscle mass loss, discuss the impact in patients most at risk, and describe the possible role of exercise as a management strategy. We present current gaps within the exercise oncology literature and offer several recommendations for future studies to support research translation, including (1) utilizing accurate and reliable body composition techniques to assess changes in skeletal muscle mass, (2) incorporating comprehensive assessments of patient health status to allow personalized exercise prescription, (3) coupling exercise with robust nutritional recommendations to maximize the impact on skeletal muscle outcomes, and (4) considering key exercise intervention features that may improve exercise efficacy and adherence. Ultimately, the driving forces behind skeletal muscle mass loss are complex and may impede exercise tolerability and efficacy. Our recommendations are intended to foster the design of high-quality patient-centred research studies to determine whether exercise can counteract muscle mass loss in people with cancer and, as such, improve knowledge on this topic.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid35534615,

title = {Myofibrillar Protein Synthesis Rates Are Increased in Chronically Exercised Skeletal Muscle despite Decreased Anabolic Signaling},

author = {Henning T Langer and Daniel West and Joan Senden and Simone Spuler and Luc J C Loon and Keith Baar},

doi = {10.1038/s41598-022-11621-x},

issn = {2045-2322},

year  = {2022},

date = {2022-05-01},

journal = {Scientific reports},

volume = {12},

number = {1},

pages = {7553},

abstract = {The molecular responses to acute resistance exercise are well characterized. However, how cellular signals change over time to modulate chronic adaptations to more prolonged exercise training is less well understood. We investigated anabolic signaling and muscle protein synthesis rates at several time points after acute and chronic eccentric loading. Adult rat tibialis anterior muscle was stimulated for six sets of ten repetitions, and the muscle was collected at 0 h, 6 h, 18 h and 48 h. In the last group of animals, 48 h after the first exercise bout a second bout was conducted, and the muscle was collected 6 h later (54 h total). In a second experiment, rats were exposed to four exercise sessions over the course of 2 weeks. Anabolic signaling increased robustly 6 h after the first bout returning to baseline between 18 and 48 h. Interestingly, 6 h after the second bout mTORC1 activity was significantly lower than following the first bout. In the chronically exercised rats, we found baseline anabolic signaling was decreased, whereas myofibrillar protein synthesis (MPS) was substantially increased, 48 h after the last bout of exercise. The increase in MPS occurred in the absence of changes to muscle fiber size or mass. In conclusion, we find that anabolic signaling is already diminished after the second bout of acute resistance type exercise. Further, chronic exposure to resistance type exercise training results in decreased basal anabolic signaling but increased overall MPS rates.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid35578224,

title = {"I Want to Get Myself as Fit as I Can and Not Die Just yet" - Perceptions of Exercise in People with Advanced Cancer and Cachexia: A Qualitative Study},

author = {Kelcey A Bland and Meinir Krishnasamy and Evelyn B Parr and Stella Mulder and Peter Martin and Luc J C Loon and Prue Cormie and Natasha Michael and Eva M Zopf},

doi = {10.1186/s12904-022-00948-x},

issn = {1472-684X},

year  = {2022},

date = {2022-05-01},

journal = {BMC palliative care},

volume = {21},

number = {1},

pages = {75},

abstract = {Cachexia is a prevalent muscle wasting syndrome among people with advanced cancer that profoundly impacts patient quality of life (QoL) and physical function. Exercise can improve QoL, physical function, and overall health in people with cancer and may be an important addition to treatment approaches for cancer cachexia. Greater understanding of patients' perception of exercise can help elucidate the feasibility of implementing exercise interventions for cancer cachexia and facilitate the design of patient-centered interventions. We aimed to describe the perception of exercise in patients with advanced cancer and cachexia, and capture exercise motivators, barriers, and preferences, to inform the feasibility of exercise interventions. Individual interviews (n = 20) with patients with locally advanced or metastatic cancer with cachexia were conducted and analyzed using reflexive thematic analysis. Main themes from interviews were: 1) Life is disrupted by cancer and cachexia; 2) Exercise offers hope; 3) Exercise barriers are multifaceted; and 4) Exercise access and support are important. Participants reported that their cancer and cachexia had intensely altered their lives, including ability to exercise. Exercise was perceived as important and participants described a hope for exercise to improve their health and wellbeing. Yet, several complex exercise barriers, such as burdensome cancer symptoms and the overwhelming impact of the COVID-19 pandemic, hindered exercise participation and prevented participants from fully realizing the perceived benefits of exercise. Factors believed to improve exercise engagement and overcome exercise barriers included increased exercise support (e.g., professional supervision) and accessibility (e.g., convenient locations). Patient-reported exercise barriers and preferences can inform the design of exercise interventions, particularly within future research studies aiming to establish exercise feasibility and efficacy in people with advanced cancer and cachexia.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{hermans2022,

title = {Cheese Ingestion Increases Muscle Protein Synthesis Rates Both at Rest and during Recovery from Exercise in Healthy, Young Males: A Randomized Parallel-Group Trial},

author = {Wesley J H Hermans and Cas J Fuchs and Floris K Hendriks and Lisanne H P Houben and Joan M Senden and Lex B Verdijk and Luc J C Loon},

doi = {10.1093/jn/nxac007},

issn = {1541-6100},

year  = {2022},

date = {2022-04-01},

journal = {The Journal of nutrition},

volume = {152},

number = {4},

pages = {1022–1030},

abstract = {BACKGROUND: Protein ingestion increases muscle protein synthesis rates. The food matrix in which protein is provided can strongly modulate the postprandial muscle protein synthetic response. So far, the muscle protein synthetic response to the ingestion of whole foods remains largely unexplored.nnOBJECTIVES: To compare the impact of ingesting 30 g protein provided as milk protein or cheese on postprandial plasma amino acid concentrations and muscle protein synthesis rates at rest and during recovery from exercise in vivo in young males.nnMETHODS: In this randomized, parallel-group intervention trial, 20 healthy males aged 18-35 y ingested 30 g protein provided as cheese or milk protein concentrate following a single-legged resistance-type exercise session consisting of 12 sets of leg press and leg extension exercises. Primed, continuous intravenous L-[ring-C]-phenylalanine infusions were combined with the collection of blood and muscle tissue samples to assess postabsorptive and 4-h postprandial muscle protein synthesis rates at rest and during recovery from exercise. Data were analyzed using repeated measures Time × Group (× Leg) ANOVA.nnRESULTS: Plasma total amino acid concentrations increased after protein ingestion (Time: P ¡ 0.001), with 38% higher peak concentrations following milk protein than cheese ingestion (Time × Group: P ¡ 0.001). Muscle protein synthesis rates increased following both cheese and milk protein ingestion from 0.037 ± 0.014 to 0.055 ± 0.018%$cdot$h and 0.034 ± 0.008 to 0.056 ± 0.010%$cdot$h at rest and even more following exercise from 0.031 ± 0.010 to 0.067 ± 0.013%$cdot$h and 0.030 ± 0.008 to 0.063 ± 0.010%$cdot$h, respectively (Time: all P ¡ 0.05; Time × Leg: P = 0.002), with no differences between cheese and milk protein ingestion (Time × Group: both P ¿ 0.05).nnCONCLUSION: Cheese ingestion increases muscle protein synthesis rates both at rest and during recovery from exercise. The postprandial muscle protein synthetic response to the ingestion of cheese or milk protein does not differ when 30 g protein is ingested at rest or during recovery from exercise in healthy, young males.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid34642762,

title = {Ingestion of Free Amino Acids Compared with an Equivalent Amount of Intact Protein Results in More Rapid Amino Acid Absorption and Greater Postprandial Plasma Amino Acid Availability without Affecting Muscle Protein Synthesis Rates in Young Adults in a Double-Blind Randomized Trial},

author = {Michelle E G Weijzen and Rob J J Gassel and Imre W K Kouw and Jorn Trommelen and Stefan H M Gorissen and Janneau Kranenburg and Joy P B Goessens and Marcel C G Poll and Lex B Verdijk and Luc J C Loon},

doi = {10.1093/jn/nxab305},

issn = {1541-6100},

year  = {2022},

date = {2022-01-01},

journal = {The Journal of nutrition},

volume = {152},

number = {1},

pages = {59–67},

abstract = {BACKGROUND: The rate of protein digestion and amino acid absorption determines the postprandial rise in circulating amino acids and modulates postprandial muscle protein synthesis rates.nnOBJECTIVE: We sought to compare protein digestion, amino acid absorption kinetics, and the postprandial muscle protein synthetic response following ingestion of intact milk protein or an equivalent amount of free amino acids.nnMETHODS: Twenty-four healthy, young participants (mean ± SD age: 22 ± 3 y and BMI 23 ± 2 kg/m2; sex: 12 male and 12 female participants) received a primed continuous infusion of l-[ring-2H5]-phenylalanine and l-[ring-3,5-2H2]-tyrosine, after which they ingested either 30 g intrinsically l-[1-13C]-phenylalanine-labeled milk protein or an equivalent amount of free amino acids labeled with l-[1-13C]-phenylalanine. Blood samples and muscle biopsies were obtained to assess protein digestion and amino acid absorption kinetics (secondary outcome), whole-body protein net balance (secondary outcome), and mixed muscle protein synthesis rates (primary outcome) throughout the 6-h postprandial period.nnRESULTS: Postprandial plasma amino acid concentrations increased after ingestion of intact milk protein and free amino acids (both P ¡ 0.001), with a greater increase following ingestion of the free amino acids than following ingestion of intact milk protein (P-time × treatment ¡ 0.001). Exogenous phenylalanine release into plasma, assessed over the 6-h postprandial period, was greater with free amino acid ingestion (76 ± 9%) than with milk protein treatment (59 ± 10%; P ¡ 0.001). Ingestion of free amino acids and intact milk protein increased mixed muscle protein synthesis rates (P-time ¡ 0.001), with no differences between treatments (from 0.037 ± 0.015%/h to 0.053 ± 0.014%/h and 0.039 ± 0.016%/h to 0.051 ± 0.010%/h, respectively; P-time × treatment = 0.629).nnCONCLUSIONS: Ingestion of a bolus of free amino acids leads to more rapid amino acid absorption and greater postprandial plasma amino acid availability than ingestion of an equivalent amount of intact milk protein. Ingestion of free amino acids may be preferred over ingestion of intact protein in conditions where protein digestion and amino acid absorption are compromised.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid34666201,

title = {Impact of Magnesium on Bone Health in Older Adults: A Systematic Review and Meta-Analysis},

author = {Inge Groenendijk and Marieke Delft and Pieter Versloot and Luc J C Loon and Lisette C P G M Groot},

doi = {10.1016/j.bone.2021.116233},

issn = {1873-2763},

year  = {2022},

date = {2022-01-01},

journal = {Bone},

volume = {154},

pages = {116233},

abstract = {BACKGROUND: Magnesium plays a key role in bone health and may, therefore, represent an interesting nutrient for the prevention of bone loss and osteoporosis. The aim of this systematic review and meta-analysis was to investigate the impact of magnesium intake from any source on bone mineral density (BMD), bone mineral content (BMC), bone turnover markers, and fracture risk in older adults.nnMETHODS: A systematic search was conducted using Embase, Medline Ovid and Cochrane Central from database inception to October 2020. All studies that related magnesium intake with bone health outcomes among adults aged $geq$60 years were included. Two investigators independently conducted abstract and full-text screenings, data extractions, and risk of bias assessments. Authors were contacted for missing data.nnRESULTS: Once 787 records were screened, six cohort studies, one case-control study and five cross-sectional studies were included. Qualitative evaluation demonstrated a positive trend between higher magnesium intake and higher hip and femoral neck BMD. Meta-analysis of four studies showed a significant positive association between magnesium intake and hip BMD (pooled beta: 0.03, 95% CI: 0.01-0.06, p ¡ 0.05).nnCONCLUSIONS: This systematic review indicates that a higher magnesium intake may support an increase in hip and femoral neck BMD. Due to limited research no associations with BMD at other sites or fractures were found. There is a need for properly designed cohort studies to determine the association between magnesium intake and bone health in older adults. Next, large and long-term randomized controlled trials in older adults are needed to determine whether an increase in magnesium (supplementation) intake can improve bone health. The combination of several bone nutrients (calcium, vitamin D, protein, magnesium and potentially more) may be needed for the most optimal effect on bone health and to delay or prevent the development of osteoporosis.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid35120409,

title = {Relative Validity and Reliability of Isometric Lower Extremity Strength Assessment in Older Adults by Using a Handheld Dynamometer},

author = {Pol Grootswagers and Anouk M M Vaes and Roland Hangelbroek and Michael Tieland and Luc J C Loon and Lisette C P G M Groot},

doi = {10.1177/19417381211063847},

issn = {1941-0921},

year  = {2022},

date = {2022-01-01},

journal = {Sports Health},

volume = {14},

number = {6},

pages = {899–905},

abstract = {BACKGROUND: Handheld dynamometry (HHD) is a practical alternative to traditional testing of lower extremity strength. However, its reliability and validity across different populations and settings are not clear.nnHYPOTHESIS: We hypothesize that HHD is a valid and reliable device to assess lower extremity strength in a population of older adults.nnSTUDY DESIGN: Cross-sectional/cohort.nnLEVEL OF EVIDENCE: Level 3.nnMETHODS: This study included 258 older adults ($geq$65 years). Isometric knee extension and flexion force were measured by 1 examiner, using an HHD (n = 222), including 3 repetitions to calculate within-day intrarater reliability. These measurements were repeated by the examiner in a subgroup (n = 23) to analyze intrarater reliability over a test-retest period of on average 8 weeks. In addition, HHD force measures were performed by a second examiner (n = 29) to analyze interrater reliability. In another subgroup (n = 77), isometric knee extension and flexion torque were measured by 1 examiner using both the HHD and Biodex System 4 to assess relative validity.nnRESULTS: HHD and Biodex measurements were highly correlated and showed excellent concurrent validity. HHD systematically overestimated torque as compared with Biodex by 8 N$cdot$m on average. Same-day intrarater intraclass correlation coefficients (ICCs) ranged from 0.97 to 0.98. Interrater reliability ICCs ranged from 0.83 to 0.95.nnCONCLUSION: HHD represents a reliable and valid alternative to Biodex to rank individuals on leg strength, or to assess within-person changes in leg strength over time, because of the high validity and reliability. The HHD is less suited for absolute strength assessment because of significant systematic overestimations.nnCLINICAL RELEVANCE: Clinicians are encouraged to use HHD to rank older adults on leg strength, or to assess within-person changes in leg strength over time, but not to compare readings with cut-offs or normative values.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{kouw2021,

title = {Ingestion of an Ample Amount of Meat Substitute Based on a Lysine-Enriched, Plant-Based Protein Blend Stimulates Postprandial Muscle Protein Synthesis to a Similar Extent as an Isonitrogenous Amount of Chicken in Healthy, Young Men},

author = {Imre W. K. Kouw and Philippe J. M. Pinckaers and Cindy Le Bourgot and Janneau M. X. Kranenburg and Antoine H. Zorenc and Lisette C. P. G. M. Groot and Lex Verdijk and Tim Snijders and Luc J. C. Loon},

doi = {10.1017/S0007114521004906},

issn = {1475-2662},

year  = {2021},

date = {2021-12-01},

journal = {The British Journal of Nutrition},

pages = {1–11},

abstract = {Plant-based proteins are considered to be less effective in their capacity to stimulate muscle protein synthesis when compared with animal-based protein sources, likely due to differences in amino acid contents. We compared the postprandial muscle protein synthetic response following the ingestion of a lysine-enriched plant-based protein product with an isonitrogenous amount of chicken. Twenty-four men (age 24 ± 5 years; BMI 22$cdot$9 ± 2$cdot$6 kg$cdot$m-2) participated in this parallel, double-blind, randomised controlled trial and consumed 40 g of protein as a lysine-enriched wheat and chickpea protein product (Plant, n 12) or chicken breast fillet (Chicken, n 12). Primed, continuous intravenous l-(ring-13C6)-phenylalanine infusions were applied while repeated blood and muscle samples were collected over a 5-h postprandial period to assess plasma amino acid responses, muscle protein synthesis rates and muscle anabolic signalling responses. Postprandial plasma leucine and essential amino acid concentrations were higher following Chicken (P $<$ 0$cdot$001), while plasma lysine concentrations were higher throughout in Plant (P $<$ 0$cdot$001). Total plasma amino acid concentrations did not differ between interventions (P = 0$cdot$181). Ingestion of both Plant and Chicken increased muscle protein synthesis rates from post-absorptive: 0$cdot$031 ± 0$cdot$011 and 0$cdot$031 ± 0$cdot$013 to postprandial: 0$cdot$046 ± 0$cdot$010 and 0$cdot$055 ± 0$cdot$015 % h-1, respectively (P-time $<$ 0$cdot$001), with no differences between Plant and Chicken (time x treatment P = 0$cdot$068). Ingestion of 40 g of protein in the form of a lysine-enriched plant-based protein product increases muscle protein synthesis rates to a similar extent as an isonitrogenous amount of chicken in healthy, young men. Plant-based protein products sold as meat replacers may be as effective as animal-based protein sources to stimulate postprandial muscle protein synthesis rates in healthy, young individuals.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pinckaers2021b,

title = {No Differences in Muscle Protein Synthesis Rates Following Ingestion of Wheat Protein, Milk Protein, and Their Protein Blend in Healthy, Young Males},

author = {Philippe J. M. Pinckaers and Imre W. K. Kouw and Floris K. Hendriks and Janneau M. X. Kranenburg and Lisette C. P. G. M. Groot and Lex B. Verdijk and Tim Snijders and Luc J. C. Loon},

url = {https://www.cambridge.org/core/journals/british-journal-of-nutrition/article/no-differences-in-muscle-protein-synthesis-rates-following-ingestion-of-wheat-protein-milk-protein-and-their-protein-blend-in-healthy-young-males/A26AC0AF166D8C7F305E5711B6B90217

https://www-cambridge-org.fontys.idm.oclc.org/core/services/aop-cambridge-core/content/view/A26AC0AF166D8C7F305E5711B6B90217/S0007114521000635a.pdf/div-class-title-no-differences-in-muscle-protein-synthesis-rates-following-ingestion-of-wheat-protein-milk-protein-and-their-protein-blend-in-healthy-young-males-div.pdf},

doi = {10.1017/S0007114521000635},

issn = {0007-1145, 1475-2662},

year  = {2021},

date = {2021-12-01},

urldate = {2021-12-01},

journal = {British Journal of Nutrition},

volume = {126},

number = {12},

pages = {1832–1842},

abstract = {Plant-derived proteins have been suggested to have less anabolic properties when compared with animal-derived proteins. Whether blends of plant- and animal-derived proteins can compensate for their lesser anabolic potential has not been assessed. The present study compares post-prandial muscle protein synthesis rates following the ingestion of milk protein with wheat protein or a blend of wheat plus milk protein in healthy, young males. In a randomised, double-blind, parallel-group design, 36 males (23 (sd 3) years) received a primed continuous L-[ring-13C6]-phenylalanine infusion after which they ingested 30 g milk protein (MILK), 30 g wheat protein (WHEAT) or a 30 g blend combining 15 g wheat plus 15 g milk protein (WHEAT+MILK). Blood and muscle biopsies were collected frequently for 5 h to assess post-prandial plasma amino acid profiles and subsequent myofibrillar protein synthesis rates. Ingestion of protein increased myofibrillar protein synthesis rates in all treatments (P $<$ 0$cdot$001). Post-prandial myofibrillar protein synthesis rates did not differ between MILK v. WHEAT (0$cdot$053 (sd 0$cdot$013) v. 0$cdot$056 (sd 0$cdot$012) %$cdot$h-1, respectively; t test P = 0$cdot$56) or between MILK v. WHEAT+MILK (0$cdot$053 (sd 0$cdot$013) v. 0$cdot$059 (sd 0$cdot$025) %$cdot$h-1, respectively; t test P = 0$cdot$46). In conclusion, ingestion of 30 g milk protein, 30 g wheat protein or a blend of 15 g wheat plus 15 g milk protein increases muscle protein synthesis rates in young males. Furthermore, muscle protein synthesis rates following the ingestion of 30 g milk protein do not differ from rates observed after ingesting 30 g wheat protein or a blend with 15 g milk plus 15 g wheat protein in healthy, young males.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pinckaers2021a,

title = {The Anabolic Response to Plant-Based Protein Ingestion},

author = {Philippe J. M. Pinckaers and Jorn Trommelen and Tim Snijders and Luc J. C. Loon},

url = {https://doi.org/10.1007/s40279-021-01540-8

https://pubmed-ncbi-nlm-nih-gov.fontys.idm.oclc.org/34515966/

https://pmc.ncbi.nlm.nih.gov/articles/PMC8566416/pdf/40279_2021_Article_1540.pdf},

doi = {10.1007/s40279-021-01540-8},

issn = {1179-2035},

year  = {2021},

date = {2021-09-01},

urldate = {2021-09-01},

journal = {Sports Medicine},

volume = {51},

number = {1},

pages = {59–74},

abstract = {There is a global trend of an increased interest in plant-based diets. This includes an increase in the consumption of plant-based proteins at the expense of animal-based proteins. Plant-derived proteins are now also frequently applied in sports nutrition. So far, we have learned that the ingestion of plant-derived proteins, such as soy and wheat protein, result in lower post-prandial muscle protein synthesis responses when compared with the ingestion of an equivalent amount of animal-based protein. The lesser anabolic properties of plant-based versus animal-derived proteins may be attributed to differences in their protein digestion and amino acid absorption kinetics, as well as to differences in amino acid composition between these protein sources. Most plant-based proteins have a low essential amino acid content and are often deficient in one or more specific amino acids, such as lysine and methionine. However, there are large differences in amino acid composition between various plant-derived proteins or plant-based protein sources. So far, only a few studies have directly compared the muscle protein synthetic response following the ingestion of a plant-derived protein versus a high(er) quality animal-derived protein. The proposed lower anabolic properties of plant- versus animal-derived proteins may be compensated for by (i) consuming a greater amount of the plant-derived protein or plant-based protein source to compensate for the lesser quality; (ii) using specific blends of plant-based proteins to create a more balanced amino acid profile; (iii) fortifying the plant-based protein (source) with the specific free amino acid(s) that is (are) deficient. Clinical studies are warranted to assess the anabolic properties of the various plant-derived proteins and their protein sources in vivo in humans and to identify the factors that may or may not compromise the capacity to stimulate post-prandial muscle protein synthesis rates. Such work is needed to determine whether the transition towards a more plant-based diet is accompanied by a transition towards greater dietary protein intake requirements.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid33703944,

title = {Fragile bones of elite cyclists: to treat or not to treat?},

author = {Luuk Hilkens and Pim Knuiman and Mathieu Heijboer and Robert Kempers and Asker E Jeukendrup and Luc J C van Loon and Jan-Willem van Dijk},

doi = {10.1152/japplphysiol.01034.2020},

issn = {1522-1601},

year  = {2021},

date = {2021-07-01},

journal = {J Appl Physiol (1985)},

volume = {131},

number = {1},

pages = {26--28},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid34181488,

title = {Last Word on Viewpoint: Fragile bones of elite cyclists: to treat or not to treat?},

author = {Luuk Hilkens and Pim Knuiman and Mathieu Heijboer and Robert Kempers and Asker E Jeukendrup and Luc J C van Loon and Jan-Willem van Dijk},

doi = {10.1152/japplphysiol.00375.2021},

issn = {1522-1601},

year  = {2021},

date = {2021-07-01},

journal = {J Appl Physiol (1985)},

volume = {131},

number = {1},

pages = {34--35},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid34116702,

title = {Mass spectrometry imaging of L-[ring-C]-labeled phenylalanine and tyrosine kinetics in non-small cell lung carcinoma},

author = {Jianhua Cao and Benjamin Balluff and Martijn Arts and Ludwig J Dubois and Luc J C van Loon and Tilman M Hackeng and Hans M H van Eijk and Gert Eijkel and Lara R Heij and Zita Soons and Steven W M Olde Damink and Ron M A Heeren},

doi = {10.1186/s40170-021-00262-9},

issn = {2049-3002},

year  = {2021},

date = {2021-06-01},

journal = {Cancer Metab},

volume = {9},

number = {1},

pages = {26},

abstract = {BACKGROUND: Metabolic reprogramming is a common phenomenon in tumorigenesis and tumor progression. Amino acids are important mediators in cancer metabolism, and their kinetics in tumor tissue are far from being understood completely. Mass spectrometry imaging is capable to spatiotemporally trace important endogenous metabolites in biological tissue specimens. In this research, we studied L-[ring-C]-labeled phenylalanine and tyrosine kinetics in a human non-small cell lung carcinoma (NSCLC) xenografted mouse model using matrix-assisted laser desorption/ionization Fourier-transform ion cyclotron resonance mass spectrometry imaging (MALDI-FTICR-MSI).nnMETHODS: We investigated the L-[ring-C]-Phenylalanine (C-Phe) and L-[ring-C]-Tyrosine (C-Tyr) kinetics at 10 min (n = 4), 30 min (n = 3), and 60 min (n = 4) after tracer injection and sham-treated group (n = 3) at 10 min in mouse-xenograft lung tumor tissues by MALDI-FTICR-MSI.nnRESULTS: The dynamic changes in the spatial distributions of 19 out of 20 standard amino acids are observed in the tumor tissue. The highest abundance of C-Phe was detected in tumor tissue at 10 min after tracer injection and decreased progressively over time. The overall enrichment of C-Tyr showed a delayed temporal trend compared to C-Phe in tumor caused by the Phe-to-Tyr conversion process. Specifically, C-Phe and C-Tyr showed higher abundances in viable tumor regions compared to non-viable regions.nnCONCLUSIONS: We demonstrated the spatiotemporal intra-tumoral distribution of the essential aromatic amino acid C-Phe and its de-novo synthesized metabolite C-Tyr by MALDI-FTICR-MSI. Our results explore for the first time local phenylalanine metabolism in the context of cancer tissue morphology. This opens a new way to understand amino acid metabolism within the tumor and its microenvironment.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid34211326,

title = {Undeclared Doping Substances are Highly Prevalent in Commercial Sports Nutrition Supplements},

author = {Erik Duiven and Luc J C van Loon and Laila Spruijt and Willem Koert and Olivier M de Hon},

doi = {10.52082/jssm.2021.328},

issn = {1303-2968},

year  = {2021},

date = {2021-06-01},

journal = {J Sports Sci Med},

volume = {20},

number = {2},

pages = {328--338},

abstract = {Sports nutrition supplements have previously been reported to contain undeclared doping substances. The use of such supplements can lead to general health risks and may give rise to unintentional doping violations in elite sports. To assess the prevalence of doping substances in a range of high-risk sports nutrition supplements available from Dutch web shops. A total of 66 sports nutrition supplements - identified as potentially high-risk products claiming to modulate hormone regulation, stimulate muscle mass gain, increase fat loss, and/or boost energy - were selected from 21 different brands and purchased from 17 web shops. All products were analyzed for doping substances by the UK life sciences testing company LGC, formerly known as the Laboratory of the Government Chemist, using an extended version of their ISO17025 accredited nutritional supplement screen. A total of 25 out of the 66 products (38%) contained undeclared doping substances, which included high levels of the stimulants oxilofrine, β-methylphenethylamine (BMPEA) and N,β-dimethylphenethylamine (NBDMPEA), the stimulant 4-methylhexan-2-amine (methylhexaneamine, 1,3-dimethylamylamine, DMAA), the anabolic steroids boldione (1,4-androstadiene-3,17-dione) and 5-androstene-3β,17α-diol (17α-AED), the beta-2 agonist higenamine and the beta-blocker bisoprolol. Based upon the recommended dose and the potential variability of analyte concentration, the ingestion of some products identified within this study could pose a significant risk of unintentional doping violations. In addition to inadvertent doping risks, the prescribed use of 3 products (4.5%) could likely impose general health risks.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid33951313,

title = {Basal protein synthesis rates differ between vastus lateralis and rectus abdominis muscle},

author = {Joey S J Smeets and Astrid M H Horstman and David P J van Dijk and Astrid G M van Boxtel and Joost F Ter Woorst and Steven W M Olde Damink and Olaf E M G Schijns and Luc J C van Loon},

doi = {10.1002/jcsm.12701},

issn = {2190-6009},

year  = {2021},

date = {2021-06-01},

journal = {J Cachexia Sarcopenia Muscle},

volume = {12},

number = {3},

pages = {769--778},

abstract = {BACKGROUND: In vivo muscle protein synthesis rates are typically assessed by measuring the incorporation rate of stable isotope labelled amino acids in skeletal muscle tissue collected from vastus lateralis muscle. It remains to be established whether muscle protein synthesis rates in the vastus lateralis are representative of muscle protein synthesis rates of other muscle groups. We hypothesized that post-absorptive muscle protein synthesis rates differ between vastus lateralis and rectus abdominis, pectoralis major, or temporalis muscle in vivo in humans.nnMETHODS: Twenty-four patients (62 ± 3 years, 42% female), scheduled to undergo surgery, participated in this study and underwent primed continuous intravenous infusions with l-[ring- C ]-phenylalanine. During the surgical procedures, serum samples were collected, and muscle tissue was obtained from the vastus lateralis as well as from the rectus abdominis, pectoralis major, or temporalis muscle. Fractional mixed muscle protein synthesis rates (%/h) were assessed by measuring the incorporation of l-[ring- C ]-phenylalanine into muscle tissue protein.nnRESULTS: Serum l-[ring- C ]-phenylalanine enrichments did not change throughout the infusion period. Post-absorptive muscle protein synthesis rates calculated based upon serum l-[ring- C ]-phenylalanine enrichments did not differ between vastus lateralis and rectus abdominis (0.032 ± 0.004 vs. 0.038 ± 0.003%/h), vastus lateralis and pectoralis major, (0.025 ± 0.003 vs. 0.022 ± 0.005%/h) or vastus lateralis and temporalis (0.047 ± 0.005 vs. 0.043 ± 0.005%/h) muscle, respectively (P > 0.05). When fractional muscle protein synthesis rates were calculated based upon tissue-free l-[ring- C ]-phenylalanine enrichments as the preferred precursor pool, muscle protein synthesis rates were significantly higher in rectus abdominis (0.089 ± 0.008%/h) compared with vastus lateralis (0.054 ± 0.005%/h) muscle (P < 0.01). No differences were observed between fractional muscle protein synthesis rates in vastus lateralis and pectoralis major (0.046 ± 0.003 vs. 0.041 ± 0.008%/h) or vastus lateralis and temporalis (0.073 ± 0.008 vs. 0.083 ± 0.011%/h) muscle, respectively.nnCONCLUSIONS: Post-absorptive muscle protein synthesis rates are higher in rectus abdominis when compared with vastus lateralis muscle. Post-absorptive muscle protein synthesis rates do not differ between vastus lateralis and pectoralis major or temporalis muscle. Protein synthesis rates in muscle tissue samples obtained during surgery do not necessarily represent a good proxy for appendicular skeletal muscle protein synthesis rates.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid33871558,

title = {Does supplementation with leucine-enriched protein alone and in combination with fish-oil-derived n-3 PUFA affect muscle mass, strength, physical performance, and muscle protein synthesis in well-nourished older adults? A randomized, double-blind, placebo-controlled trial},

author = {Caoileann H Murphy and Ellen M Flanagan and Giuseppe De Vito and Davide Susta and Kathleen A J Mitchelson and Elena de Marco Castro and Joan M G Senden and Joy P B Goessens and Agnieszka Mikłosz and Adrian Chabowski and Ricardo Segurado and Clare A Corish and Sinead N McCarthy and Brendan Egan and Luc J C van Loon and Helen M Roche},

doi = {10.1093/ajcn/nqaa449},

issn = {1938-3207},

year  = {2021},

date = {2021-06-01},

journal = {Am J Clin Nutr},

volume = {113},

number = {6},

pages = {1411--1427},

abstract = {BACKGROUND: Leucine-enriched protein (LEU-PRO) and long-chain (LC) n-3 (ω-3) PUFAs have each been proposed to improve muscle mass and function in older adults, whereas their combination may be more effective than either alone.nnOBJECTIVE: The impact of LEU-PRO supplementation alone and combined with LC n-3 PUFAs on appendicular lean mass, strength, physical performance and myofibrillar protein synthesis (MyoPS) was investigated in older adults at risk of sarcopenia.nnMETHODS: This 24-wk, 3-arm parallel, randomized, double-blind, placebo-controlled trial was conducted in 107 men and women aged ≥65 y with low muscle mass and/or strength. Twice daily, participants consumed a supplement containing either LEU-PRO (3 g leucine, 10 g protein; n = 38), LEU-PRO plus LC n-3 PUFAs (0.8 g EPA, 1.1 g DHA; LEU-PRO+n-3; n = 38), or an isoenergetic control (CON; n = 31). Appendicular lean mass, handgrip strength, leg strength, physical performance, and circulating metabolic and renal function markers were measured pre-, mid-, and postintervention. Integrated rates of MyoPS were assessed in a subcohort (n = 28).nnRESULTS: Neither LEU-PRO nor LEU-PRO+n-3 supplementation affected appendicular lean mass, handgrip strength, knee extension strength, physical performance or MyoPS. However, isometric knee flexion peak torque (treatment effect: -7.1 Nm; 95% CI: -12.5, -1.8 Nm; P < 0.01) was lower postsupplementation in LEU-PRO+n-3 compared with CON. Serum triacylglycerol and total adiponectin concentrations were lower, and HOMA-IR was higher, in LEU-PRO+n-3 compared with CON postsupplementation (all P < 0.05). Estimated glomerular filtration rate was higher and cystatin c was lower in LEU-PRO and LEU-PRO+n-3 postsupplementation compared with CON (all P < 0.05).nnCONCLUSIONS: Contrary to our hypothesis, we did not observe a beneficial effect of LEU-PRO supplementation alone or combined with LC n-3 PUFA supplementation on appendicular lean mass, strength, physical performance or MyoPS in older adults at risk of sarcopenia. This trial was registered at clinicaltrials.gov as NCT03429491.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid32594854,

title = {The impact of beetroot juice supplementation on muscular endurance, maximal strength and countermovement jump performance},

author = {Kristin L Jonvik and Daan Hoogervorst and Harmen B Peelen and Mark de Niet and Lex B Verdijk and Luc J C van Loon and Jan-Willem van Dijk},

doi = {10.1080/17461391.2020.1788649},

issn = {1536-7290},

year  = {2021},

date = {2021-06-01},

journal = {Eur J Sport Sci},

volume = {21},

number = {6},

pages = {871--878},

abstract = {: Dietary nitrate has been shown to enhance muscle contractile function and has, therefore, been linked to increased muscle power and sprint exercise performance. However, the impact of dietary nitrate supplementation on maximal strength, performance and muscular endurance remains to be established. : Fifteen recreationally active males (25 ± 4 y, BMI 24 ± 3 kg/m) participated in a randomized double-blinded cross-over study comprising two 6-d supplementation periods; 140 mL/d nitrate-rich (BR; 985 mg/d) and nitrate-depleted (PLA; 0.37 mg/d) beetroot juice. Three hours following the last supplement, we assessed countermovement jump (CMJ) performance, maximal strength and power of the upper leg by voluntary isometric (30° and 60° angle) and isokinetic contractions (60, 120, 180 and 300°·s), and muscular endurance (total workload) by 30 reciprocal isokinetic voluntary contractions at 180°·s. : Despite differences in plasma nitrate (BR: 879 ± 239 vs. PLA: 33 ± 13 μmol/L,  < 0.001) and nitrite (BR: 463 ± 217 vs. PLA: 176 ± 50 nmol/L,  < 0.001) concentrations prior to exercise testing, CMJ height (BR: 39.3 ± 6.3 vs. PLA: 39.6 ± 6.3 cm;  = 0.39) and muscular endurance (BR: 3.93 ± 0.69 vs. PLA: 3.90 ± 0.66 kJ;  = 0.74) were not different between treatments. In line, isometric strength ( > 0.50 for both angles) and isokinetic knee extension power ( > 0.33 for all velocities) did not differ between treatments. Isokinetic knee flexion power was significantly higher following BR compared with PLA ingestion at 60°·s ( = 0.001), but not at 120°·s ( = 0.24), 180°·s ( = 0.066), and 300°·s ( = 0.36). : Nitrate supplementation does not improve maximal strength, countermovement jump performance and muscular endurance in healthy, active males.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid33601335,

title = {Daily Myofibrillar Protein Synthesis Rates in Response to Low- and High-Frequency Resistance Exercise Training in Healthy, Young Men},

author = {Brandon J Shad and Janice L Thompson and James Mckendry and Andrew M Holwerda and Yasir S Elhassan and Leigh Breen and Luc J C van Loon and Gareth A Wallis},

doi = {10.1123/ijsnem.2020-0274},

issn = {1543-2742},

year  = {2021},

date = {2021-05-01},

journal = {Int J Sport Nutr Exerc Metab},

volume = {31},

number = {3},

pages = {209--216},

abstract = {The impact of resistance exercise frequency on muscle protein synthesis rates remains unknown. The aim of this study was to compare daily myofibrillar protein synthesis rates over a 7-day period of low-frequency (LF) versus high-frequency (HF) resistance exercise training. Nine young men (21 ± 2 years) completed a 7-day period of habitual physical activity (BASAL). This was followed by a 7-day exercise period of volume-matched, LF (10 × 10 repetitions at 70% one-repetition maximum, once per week) or HF (2 × 10 repetitions at ∼70% one-repetition maximum, five times per week) resistance exercise training. The participants had one leg randomly allocated to LF and the other to HF. Skeletal muscle biopsies and daily saliva samples were collected to determine myofibrillar protein synthesis rates using 2H2O, with intracellular signaling determined using Western blotting. The myofibrillar protein synthesis rates did not differ between the LF (1.46 ± 0.26%/day) and HF (1.48 ± 0.33%/day) conditions over the 7-day exercise training period (p > .05). There were no significant differences between the LF and HF conditions over the first 2 days (1.45 ± 0.41%/day vs. 1.25 ± 0.46%/day) or last 5 days (1.47 ± 0.30%/day vs. 1.50 ± 0.41%/day) of the exercise training period (p > .05). Daily myofibrillar protein synthesis rates were not different from BASAL at any time point during LF or HF (p > .05). The phosphorylation status and total protein content of selected proteins implicated in skeletal muscle ribosomal biogenesis were not different between conditions (p > .05). Under the conditions of the present study, resistance exercise training frequency did not modulate daily myofibrillar protein synthesis rates in young men.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid33588378,

title = {Exercise Plus Presleep Protein Ingestion Increases Overnight Muscle Connective Tissue Protein Synthesis Rates in Healthy Older Men},

author = {Andrew M Holwerda and Jorn Trommelen and Imre W K Kouw and Joan M Senden and Joy P B Goessens and Janneau van Kranenburg and Annemie P Gijsen and Lex B Verdijk and Luc J C van Loon},

doi = {10.1123/ijsnem.2020-0222},

issn = {1543-2742},

year  = {2021},

date = {2021-05-01},

journal = {Int J Sport Nutr Exerc Metab},

volume = {31},

number = {3},

pages = {217--226},

abstract = {Protein ingestion and exercise stimulate myofibrillar protein synthesis rates. When combined, exercise further increases the postprandial rise in myofibrillar protein synthesis rates. It remains unclear whether protein ingestion with or without exercise also stimulates muscle connective tissue protein synthesis rates. The authors assessed the impact of presleep protein ingestion on overnight muscle connective tissue protein synthesis rates at rest and during recovery from resistance-type exercise in older men. Thirty-six healthy, older men were randomly assigned to ingest 40 g intrinsically L-[1-13C]-phenylalanine and L-[1-13C]-leucine-labeled casein protein (PRO, n = 12) or a nonprotein placebo (PLA, n = 12) before going to sleep. A third group performed a single bout of resistance-type exercise in the evening before ingesting 40 g intrinsically-labeled casein protein prior to sleep (EX+PRO, n = 12). Continuous intravenous infusions of L-[ring-2H5]-phenylalanine and L-[1-13C]-leucine were applied with blood and muscle tissue samples collected throughout overnight sleep. Presleep protein ingestion did not increase muscle connective tissue protein synthesis rates (0.049 ± 0.013 vs. 0.060 ± 0.024%/hr in PLA and PRO, respectively; p = .73). Exercise plus protein ingestion resulted in greater overnight muscle connective tissue protein synthesis rates (0.095 ± 0.022%/hr) when compared with PLA and PRO (p < .01). Exercise increased the incorporation of dietary protein-derived amino acids into muscle connective tissue protein (0.036 ± 0.013 vs. 0.054 ± 0.009 mole percent excess in PRO vs. EX+PRO, respectively; p < .01). In conclusion, resistance-type exercise plus presleep protein ingestion increases overnight muscle connective tissue protein synthesis rates in older men. Exercise enhances the utilization of dietary protein-derived amino acids as precursors for de novo muscle connective tissue protein synthesis during overnight sleep.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid33487181,

title = {Comprehensive assessment of post-prandial protein handling by the application of intrinsically labelled protein  in human subjects},

author = {Jorn Trommelen and Andrew M Holwerda and Philippe J M Pinckaers and Luc J C van Loon},

doi = {10.1017/S0029665120008034},

issn = {1475-2719},

year  = {2021},

date = {2021-05-01},

journal = {Proc Nutr Soc},

volume = {80},

number = {2},

pages = {221--229},

abstract = {All human tissues are in a constant state of remodelling, regulated by the balance between tissue protein synthesis and breakdown rates. It has been well-established that protein ingestion stimulates skeletal muscle and whole-body protein synthesis. Stable isotope-labelled amino acid methodologies are commonly applied to assess the various aspects of protein metabolism in vivo in human subjects. However, to achieve a more comprehensive assessment of post-prandial protein handling in vivo in human subjects, intravenous stable isotope-labelled amino acid infusions can be combined with the ingestion of intrinsically labelled protein and the collection of blood and muscle tissue samples. The combined application of ingesting intrinsically labelled protein with continuous intravenous stable isotope-labelled amino acid infusion allows the simultaneous assessment of protein digestion and amino acid absorption kinetics (e.g. release of dietary protein-derived amino acids into the circulation), whole-body protein metabolism (whole-body protein synthesis, breakdown and oxidation rates and net protein balance) and skeletal muscle metabolism (muscle protein fractional synthesis rates and dietary protein-derived amino acid incorporation into muscle protein). The purpose of this review is to provide an overview of the various aspects of post-prandial protein handling and metabolism with a focus on insights obtained from studies that have applied intrinsically labelled protein under a variety of conditions in different populations.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid33399528,

title = {Assessing the whole-body protein synthetic response to feeding  in human subjects},

author = {Jorn Trommelen and Luc J C van Loon},

doi = {10.1017/S0029665120008009},

issn = {1475-2719},

year  = {2021},

date = {2021-05-01},

journal = {Proc Nutr Soc},

volume = {80},

number = {2},

pages = {139--147},

abstract = {All tissues are in a constant state of turnover, with a tightly controlled regulation of protein synthesis and breakdown rates. Due to the relative ease of sampling skeletal muscle tissue, basal muscle protein synthesis rates and the protein synthetic responses to various anabolic stimuli have been well defined in human subjects. In contrast, only limited data are available on tissue protein synthesis rates in other organs. Several organs such as the brain, liver and pancreas, show substantially higher (basal) protein synthesis rates when compared to skeletal muscle tissue. Such data suggest that these tissues may also possess a high level of plasticity. It remains to be determined whether protein synthesis rates in these tissues can be modulated by external stimuli. Whole-body protein synthesis rates are highly responsive to protein intake. As the contribution of muscle protein synthesis rates to whole-body protein synthesis rates is relatively small considering the large amount of muscle mass, this suggests that other organ tissues may also be responsive to (protein) feeding. Whole-body protein synthesis rates in the fasted or fed state can be quantified by measuring plasma amino acid kinetics, although this requires the production of intrinsically labelled protein. Protein intake requirements to maximise whole-body protein synthesis may also be determined by the indicator amino acid oxidation technique, but the technique does not allow the assessment of actual protein synthesis and breakdown rates. Both approaches have several other methodological and inferential limitations that will be discussed in detail in this paper.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid33314750,

title = {Myonuclear content and domain size in small versus larger muscle fibres in response to 12 weeks of resistance exercise training in older adults},

author = {Tim Snijders and Andy M Holwerda and Luc J C van Loon and Lex B Verdijk},

doi = {10.1111/apha.13599},

issn = {1748-1716},

year  = {2021},

date = {2021-04-01},

journal = {Acta Physiol (Oxf)},

volume = {231},

number = {4},

pages = {e13599},

abstract = {AIM: To assess the relation between muscle fibre hypertrophy and myonuclear accretion in relatively small and large muscle fibre size clusters following prolonged resistance exercise training in older adults.nnMETHODS: Muscle biopsies were collected before and after 12 weeks of resistance exercise training in 40 healthy, older men (70 ± 3 years). All muscle fibres were ordered by size and categorized in four muscle fibre size clusters: 'Small': 2000-3999 µm , 'Moderate': 4000-5999 µm , 'Large': 6000-7999 µm and 'Largest': 8000-9999 µm . Changes in muscle fibre size cluster distribution were related to changes in muscle fibre size, myonuclear content and myonuclear domain size.nnRESULTS: With training, the percentage of muscle fibres decreased in the Small (from 23 ± 12 to 17 ± 14%, P < .01) and increased in the Largest (from 11 ± 8 to 15 ± 10%, P < .01) muscle fibre size clusters. The decline in the percentage of Small muscle fibres was accompanied by an increase in overall myonuclear domain size (r = -.466, P = .002) and myonuclear content (r = -.390, P = .013). In contrast, the increase in the percentage of the Largest muscle fibres was accompanied by an overall increase in myonuclear content (r = .616, P < .001), but not in domain size.nnCONCLUSION: Prolonged resistance-type exercise training induces a decline in the percentage of small as well as an increase in the percentage of the largest muscle fibres in older adults. Whereas the change in the percentage of small fibres is best predicted by an increase in overall myonuclear domain size, the change in the percentage of the largest fibres is associated with an overall increase in myonuclear content.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Trommelen2021,

title = {Gut amino acid absorption in humans: Concepts and relevance for postprandial metabolism},

author = {Jorn Trommelen and Daniel Tomé and Luc J.C. van Loon},

doi = {10.1016/j.nutos.2020.12.006},

issn = {2667-2685},

year  = {2021},

date = {2021-04-00},

journal = {Clinical Nutrition Open Science},

volume = {36},

pages = {43--55},

publisher = {Elsevier BV},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid32469388,

title = {Dietary protein intake does not modulate daily myofibrillar protein synthesis rates or loss of muscle mass and function during short-term immobilization in young men: a randomized controlled trial},

author = {Sean Paul Kilroe and Jonathan Fulford and Sarah Jackman and Andrew Holwerda and Annemie Gijsen and Luc van Loon and Benjamin Toby Wall},

doi = {10.1093/ajcn/nqaa136},

issn = {1938-3207},

year  = {2021},

date = {2021-03-01},

journal = {Am J Clin Nutr},

volume = {113},

number = {3},

pages = {548--561},

abstract = {BACKGROUND: Short-term (<1 wk) muscle disuse lowers daily myofibrillar protein synthesis (MyoPS) rates resulting in muscle mass loss. The understanding of how daily dietary protein intake influences such muscle deconditioning requires further investigation.nnOBJECTIVES: To assess the influence of graded dietary protein intakes on daily MyoPS rates and the loss of muscle mass during 3 d of disuse.nnMETHODS: Thirty-three healthy young men (aged 22 ± 1 y; BMI = 23 ± 1 kg/m2) initially consumed the same standardized diet for 5 d, providing 1.6 g protein/kg body mass/d. Thereafter, participants underwent a 3-d period of unilateral leg immobilization during which they were randomly assigned to 1 of 3 eucaloric diets containing relatively high, low, or no protein (HIGH: 1.6, LOW: 0.5, NO: 0.15 g protein/kg/d; n = 11 per group). One day prior to immobilization participants ingested 400 mL deuterated water (D2O) with 50-mL doses consumed daily thereafter. Prior to and immediately after immobilization upper leg bilateral MRI scans and vastus lateralis muscle biopsies were performed to measure quadriceps muscle volume and daily MyoPS rates, respectively.nnRESULTS: Quadriceps muscle volume of the control legs remained unchanged throughout the experiment (P > 0.05). Immobilization led to 2.3 ± 0.4%, 2.7 ± 0.2%, and 2.0 ± 0.4% decreases in quadriceps muscle volume (P < 0.05) of the immobilized leg in the HIGH, LOW, and NO groups (P < 0.05), respectively, with no significant differences between groups (P > 0.05). D2O ingestion resulted in comparable plasma free [2H]-alanine enrichments during immobilization (∼2.5 mole percentage excess) across groups (P > 0.05). Daily MyoPS rates during immobilization were 30 ± 2% (HIGH), 26 ± 3% (LOW), and 27 ± 2% (NO) lower in the immobilized compared with the control leg, with no significant differences between groups (P > 0.05).nnCONCLUSIONS: Three days of muscle disuse induces considerable declines in muscle mass and daily MyoPS rates. However, daily protein intake does not modulate any of these muscle deconditioning responses.Clinical trial registry number: NCT03797781.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid33012216,

title = {Whey protein supplementation does not accelerate recovery from a single bout of eccentric exercise},

author = {Luuk Hilkens and Jolien De Bock and Joris Kretzers and Alwine F M Kardinaal and Esther G Floris-Vollenbroek and Petra A M J Scholtens and Astrid M H Horstman and Luc J C van Loon and Jan-Willem van Dijk},

doi = {10.1080/02640414.2020.1820184},

issn = {1466-447X},

year  = {2021},

date = {2021-02-01},

journal = {J Sports Sci},

volume = {39},

number = {3},

pages = {322--331},

abstract = {The current double blind, randomized, placebo-controlled trial with two parallel groups aimed to assess the impact of whey protein supplementation on recovery of muscle function and muscle soreness following eccentric exercise. During a 9-day period, forty recreationally active males received twice daily supplementation with either whey protein (PRO; 60 g/day) or an iso-energetic amount of carbohydrate (CON). Muscle function and soreness were assessed before, and 0, 3, 24, 48, and 72 h after performing 100 drop jumps. Recovery of isometric maximal voluntary contraction (MVC) did not significantly differ between groups (timextreatment,  = 0.56). In contrast, the recovery of isokinetic MVC at 90°·s was faster in CON as opposed to PRO (timextreatment interaction,  = 0.044). Recovery of isokinetic MVC at 180°·s was also faster in CON as opposed to PRO (timextreatment interaction,  = 0.011). Recovery of countermovement jump performance did not differ between groups (timextreatment interaction,  = 0.52). Muscle soreness, CK and CRP showed a transient increase over time ( < 0.001), with no differences between groups. In conclusion, whey protein supplementation does not accelerate recovery of muscle function or attenuate muscle soreness and inflammation during 3 days of recovery from a single bout of eccentric exercise.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid34707570,

title = {Hepatic Steatosis Contributes to the Development of Muscle Atrophy  Inter-Organ Crosstalk},

author = {Kenneth Pasmans and Michiel E Adriaens and Peter Olinga and Ramon Langen and Sander S Rensen and Frank G Schaap and Steven W M Olde Damink and Florian Caiment and Luc J C van Loon and Ellen E Blaak and Ruth C R Meex},

doi = {10.3389/fendo.2021.733625},

issn = {1664-2392},

year  = {2021},

date = {2021-01-01},

journal = {Front Endocrinol (Lausanne)},

volume = {12},

pages = {733625},

abstract = {Individuals with hepatic steatosis often display several metabolic abnormalities including insulin resistance and muscle atrophy. Previously, we found that hepatic steatosis results in an altered hepatokine secretion profile, thereby inducing skeletal muscle insulin resistance  inter-organ crosstalk. In this study, we aimed to investigate whether the altered secretion profile in the state of hepatic steatosis also induces skeletal muscle atrophy  effects on muscle protein turnover. To investigate this, eight-week-old male C57BL/6J mice were fed a chow (4.5% fat) or a high-fat diet (HFD; 45% fat) for 12 weeks to induce hepatic steatosis, after which the livers were excised and cut into ~200-µm slices. Slices were cultured to collect secretion products (conditioned medium; CM). Differentiated L6-GLUT4myc myotubes were incubated with chow or HFD CM to measure glucose uptake. Differentiated C2C12 myotubes were incubated with chow or HFD CM to measure protein synthesis and breakdown, and gene expression  RNA sequencing. Furthermore, proteomics analysis was performed in chow and HFD CM. It was found that HFD CM caused insulin resistance in L6-GLUT4myc myotubes compared with chow CM, as indicated by a blunted insulin-stimulated increase in glucose uptake. Furthermore, protein breakdown was increased in C2C12 cells incubated with HFD CM, while there was no effect on protein synthesis. RNA profiling of C2C12 cells indicated that 197 genes were differentially expressed after incubation with HFD CM, compared with chow CM, and pathway analysis showed that pathways related to anatomical structure and function were enriched. Proteomics analysis of the CM showed that 32 proteins were differentially expressed in HFD CM compared with chow CM. Pathway enrichment analysis indicated that these proteins had important functions with respect to insulin-like growth factor transport and uptake, and affect post-translational processes, including protein folding, protein secretion and protein phosphorylation. In conclusion, the results of this study support the hypothesis that secretion products from the liver contribute to the development of muscle atrophy in individuals with hepatic steatosis.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid33491039,

title = {Higher Levels of Physical Activity Are Associated with Greater Fruit and Vegetable intake in Older Adults},

author = {C M T van der Avoort and D S M Ten Haaf and J H M de Vries and L B Verdijk and L J C van Loon and T M H Eijsvogels and M T E Hopman},

doi = {10.1007/s12603-020-1520-3},

issn = {1760-4788},

year  = {2021},

date = {2021-01-01},

journal = {J Nutr Health Aging},

volume = {25},

number = {2},

pages = {230--241},

abstract = {OBJECTIVE: High levels of physical activity (PA) and optimal nutrition independently improve healthy aging, but few data are available about how PA may influence food preferences in older populations. Therefore, the aim of our study was to establish if there is an association between habitual PA and intake of nutrient-dense foods (i.e. fruits and vegetables).nnDESIGN: A cross-sectional survey was conducted.nnSETTING: The Netherlands.nnPARTICIPANTS: 2466 older adults (56% male, age 62±9 yr).nnMEASUREMENTS: PA was assessed using the short questionnaire to assess health (SQUASH) and participants were classified into quintiles of weekly PA (MET-h/wk). Total fruit and vegetable intake was assessed using a validated food frequency questionnaire (FFQ) and were corrected for energy intake (g/kcal/d) in the analyses. Multiple regression analyses were performed to determine the association between PA and fruit and vegetable intake, including covariates.nnRESULTS: Being in the higher quintiles of PA (Q3, Q4 and Q5) was positively associated with more daily fruit and vegetable consumption, even after correction for total energy intake (Q3; β=0.089, P<0.001, Q4; β=0.047, P=0.024, Q5; β=0.098, P<0.001).nnCONCLUSIONS: Older adults who are moderately to highly physically active tend to consume more fruit and vegetable compared to less active peers, when corrected for total energy intake. Female gender, under- and overreporting dietary intake (Goldberg score), non-smoking, high level of education, less alcohol consumption and a lower body mass index positivity affected this relationship. Our data will help health-care professionals to accelerate their efforts to treat and prevent chronic diseases.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid33227401,

title = {Muscle fiber capillarization is associated with various indices of skeletal muscle mass in healthy, older men},

author = {M W Betz and T Aussieker and C Q Kruger and S H M Gorissen and L J C van Loon and T Snijders},

doi = {10.1016/j.exger.2020.111161},

issn = {1873-6815},

year  = {2021},

date = {2021-01-01},

journal = {Exp Gerontol},

volume = {143},

pages = {111161},

abstract = {INTRODUCTION: Muscle fiber capillarization plays a fundamental role in the regulation of skeletal muscle mass maintenance. However, it remains unclear to what extent capillarization is related to various other skeletal muscle characteristics. In this study we determined whether muscle fiber capillarization is independently associated with measures of skeletal muscle mass, both on a whole-body and cellular level, and post-absorptive muscle protein synthesis rates in healthy older men.nnMETHODS: Forty-six healthy older (70 ± 4 y) men participated in a trial during which basal muscle protein synthesis rates were assessed using stable isotope tracer methodology. Blood and muscle biopsy samples were collected to assess post-absorptive muscle protein synthesis rates over a 3-hour period. Immunohistochemistry was performed to determine various indices of muscle fiber capillarization, size, type distribution, and myonuclear content/domain size. Dual energy x-ray absorptiometry scans were performed to determine whole-body and appendicular lean tissue mass.nnRESULTS: Capillary-to-fiber ratio (C/Fi) and perimeter exchange (CFPE) index correlated with whole-body lean tissue mass (r = 0.43, P < 0.01 and r = 0.25, P < 0.10, respectively), appendicular lean tissue mass (r = 0.52, P < 0.001 and r = 0.37, P < 0.05, respectively) as well as appendicular lean tissue mass divided by body mass index (r = 0.65, P < 0.001 and r = 0.62, P < 0.001, respectively). Muscle fiber size correlated with C/Fi (r = 0.45, P < 0.01), but not with CFPE index. No associations were observed between different indices of muscle fiber capillarization and post-absorptive muscle protein synthesis rates in healthy, older men.nnCONCLUSION: The present study provides further evidence that muscle fiber capillarization may be a critical factor in the regulation of skeletal muscle maintenance in healthy older men.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid33060457,

title = {Dietary protein interventions to improve nutritional status in end-stage renal disease patients undergoing hemodialysis},

author = {Floris K Hendriks and Jeroen P Kooman and Luc J C van Loon},

doi = {10.1097/MCO.0000000000000703},

issn = {1473-6519},

year  = {2021},

date = {2021-01-01},

journal = {Curr Opin Clin Nutr Metab Care},

volume = {24},

number = {1},

pages = {79--87},

abstract = {PURPOSE OF REVIEW: Poor nutritional status is prevalent among end-stage renal disease patients undergoing hemodialysis. Chronic hemodialysis patients show an accelerated decline in skeletal muscle mass and strength, which is associated with higher mortality rates and a reduced quality of life. The current review aims to summarize recent advances regarding underlying causes of muscle loss and interventions that support muscle mass maintenance in patients with chronic hemodialysis.nnRECENT FINDINGS: Muscle maintenance in chronic hemodialysis patients is compromised by low dietary protein intake levels, anabolic resistance of skeletal muscle tissue, sedentary behavior, and amino acid removal during hemodialysis. Studies assessing the effect of increased protein intake on nutritional status generally show beneficial results, especially in hypoalbuminemic chronic hemodialysis patients. The muscle protein synthetic response following protein ingestion in chronic hemodialysis patients may be enhanced through incorporation of structured physical activity and/or concurrent ketoacid ingestion.nnSUMMARY: A coordinated program that combines nutritional and physical activity interventions is likely required to attenuate the decline in muscle mass and strength of chronic hemodialysis patients. Nephrologists, dieticians, and exercise specialists should collaborate closely to establish guidelines regarding the appropriate quantity and timing of protein ingestion. In addition, they should provide tailored nutritional and physical activity interventions for chronic hemodialysis patients (see video, Supplemental Digital Content 1, Video abstract, http://links.lww.com/COCN/A14).},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{HERMANS2021934,

title = {Insects Are a Viable Protein Source for Human Consumption: From Insect Protein Digestion to Postprandial Muscle Protein Synthesis in Vivo in Humans: A Double-Blind Randomized Trial},

author = {Wesley JH Hermans and Joan M Senden and Tyler A Churchward-Venne and Kevin JM Paulussen and Cas J Fuchs and Joey SJ Smeets and Joop JA Loon and Lex B Verdijk and Luc JC Loon},

url = {https://pmc.ncbi.nlm.nih.gov/articles/PMC8408844/pdf/nqab115.pdf

https://pubmed-ncbi-nlm-nih-gov.fontys.idm.oclc.org/34020450/},

doi = {10.1093/ajcn/nqab115},

issn = {0002-9165},

year  = {2021},

date = {2021-01-01},

urldate = {2021-01-01},

journal = {The American Journal of Clinical Nutrition},

volume = {114},

number = {3},

pages = {934–944},

abstract = {ABSTRACT Background Insects have recently been identified as a more sustainable protein-dense food source and may represent a viable alternative to conventional animal-derived proteins. Objectives We aimed to compare the impacts of ingesting lesser mealworm– and milk-derived protein on protein digestion and amino acid absorption kinetics, postprandial skeletal muscle protein synthesis rates, and the incorporation of dietary protein–derived amino acids into de novo muscle protein at rest and during recovery from exercise in vivo in humans. Methods In this double-blind randomized controlled trial, 24 healthy, young men ingested 30 g specifically produced, intrinsically l-[1-13C]-phenylalanine and l-[1-13C]-leucine labeled lesser mealworm– or milk-derived protein after a unilateral bout of resistance-type exercise. Primed continuous l-[ring-2H5]-phenylalanine, l-[ring-3,5-2H2]-tyrosine, and l-[1-13C]-leucine infusions were applied, with frequent collection of blood and muscle tissue samples. Results A total of 73Conclusions Ingestion of a meal-like amount of lesser mealworm–derived protein is followed by rapid protein digestion and amino acid absorption and increases muscle protein synthesis rates both at rest and during recovery from exercise. The postprandial protein handling of lesser mealworm does not differ from ingesting an equivalent amount of milk protein concentrate in vivo in humans. This trial was registered at www.trialregister.nl as NL6897.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{VANDERAVOORT20212667,

title = {Increasing Nitrate-Rich Vegetable Intake Lowers Ambulatory Blood Pressure in (Pre)Hypertensive Middle-Aged and Older Adults: A 12-Wk Randomized Controlled Trial},

author = {Cindy M T Avoort and Dominique S M Haaf and Coen C W G Bongers and Frederieke Oorschot and Lex B Verdijk and Luc J C Loon and Maria T E Hopman},

url = {https://www.sciencedirect.com/science/article/pii/S0022316622003352

https://pubmed-ncbi-nlm-nih-gov.fontys.idm.oclc.org/34236392/

https://www-sciencedirect-com.fontys.idm.oclc.org/science/article/pii/S0022316622003352?via%3Dihub},

doi = {10.1093/jn/nxab157},

issn = {0022-3166},

year  = {2021},

date = {2021-01-01},

urldate = {2021-01-01},

journal = {The Journal of Nutrition},

volume = {151},

number = {9},

pages = {2667–2679},

abstract = {Background Emerging evidence suggests that increasing dietary nitrate intake may be an effective approach to improve cardiovascular health. However, the effects of a prolonged elevation of nitrate intake through an increase in vegetable consumption are understudied. Objective Our primary aim was to determine the impact of 12 wk of increased daily consumption of nitrate-rich vegetables or nitrate supplementation on blood pressure (BP) in (pre)hypertensive middle-aged and older adults. Methods In a 12-wk randomized, controlled study (Nijmegen, The Netherlands), 77 (pre)hypertensive participants (BP: 144 ± 13/87 ± 7 mmHg, age: 65 ± 10 y) either received an intervention with personalized monitoring and feedback aiming to consume $sim$250–300 g nitrate-rich vegetables/d ($sim$350–400 mg nitrate/d; n = 25), beetroot juice supplementation (400 mg nitrate/d; n = 26), or no intervention (control; n = 26). Before and after intervention, 24-h ambulatory BP was measured. Data were analyzed using repeated measures ANOVA (time × treatment), followed by within-group (paired t-test) and between-group analyses (1-factor ANOVA) where appropriate. Results The 24-h systolic BP (SBP) (primary outcome) changed significantly (P-interaction time × treatment = 0.017) with an increase in the control group (131 ± 8 compared with 135 ± 10 mmHg; P = 0.036); a strong tendency for a decline in the nitrate-rich vegetable group (129 ± 10 compared with 126 ± 9 mmHg; P = 0.051) which was different from control (P = 0.020); but no change in the beetroot juice group (133 ± 11 compared with 132 ± 12 mmHg; P = 0.56). A significant time × treatment interaction was also found for daytime SBP (secondary outcome},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid32936440,

title = {Primary, Secondary, and Tertiary Effects of Carbohydrate Ingestion During Exercise},

author = {Ian Rollo and Javier T Gonzalez and Cas J Fuchs and Luc J C van Loon and Clyde Williams},

url = {https://pmc.ncbi.nlm.nih.gov/articles/PMC8589735/pdf/40279_2021_Article_1489.pdf

https://pubmed-ncbi-nlm-nih-gov.fontys.idm.oclc.org/34043186/},

doi = {10.1007/s40279-020-01343-3},

issn = {1179-2035},

year  = {2020},

date = {2020-11-01},

urldate = {2020-11-01},

journal = {Sports Med},

volume = {50},

number = {11},

pages = {1863--1871},

abstract = {The purpose of this current opinion paper is to describe the journey of ingested carbohydrate from 'mouth to mitochondria' culminating in energy production in skeletal muscles during exercise. This journey is conveniently described as primary, secondary, and tertiary events. The primary stage is detection of ingested carbohydrate by receptors in the oral cavity and on the tongue that activate reward and other centers in the brain leading to insulin secretion. After digestion, the secondary stage is the transport of monosaccharides from the small intestine into the systemic circulation. The passage of these monosaccharides is facilitated by the presence of various transport proteins. The intestinal mucosa has carbohydrate sensors that stimulate the release of two 'incretin' hormones (GIP and GLP-1) whose actions range from the secretion of insulin to appetite regulation. Most of the ingested carbohydrate is taken up by the liver resulting in a transient inhibition of hepatic glucose release in a dose-dependent manner. Nonetheless, the subsequent increased hepatic glucose (and lactate) output can increase exogenous carbohydrate oxidation rates by 40-50%. The recognition and successful distribution of carbohydrate to the brain and skeletal muscles to maintain carbohydrate oxidation as well as prevent hypoglycaemia underpins the mechanisms to improve exercise performance.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid32735362,

title = {In vitro ketone-supported mitochondrial respiration is minimal when other substrates are readily available in cardiac and skeletal muscle},

author = {Heather L Petrick and Henver S Brunetta and Chris Pignanelli and Everson A Nunes and Luc J C van Loon and Jamie F Burr and Graham P Holloway},

doi = {10.1113/JP280032},

issn = {1469-7793},

year  = {2020},

date = {2020-11-01},

journal = {J Physiol},

volume = {598},

number = {21},

pages = {4869--4885},

abstract = {KEY POINTS: Ketone bodies are proposed to represent an alternative fuel source driving energy production, particularly during exercise. Biologically, the extent to which mitochondria utilize ketone bodies compared to other substrates remains unknown. We demonstrate in vitro that maximal mitochondrial respiration supported by ketone bodies is low when compared to carbohydrate-derived substrates in the left ventricle and red gastrocnemius muscle from rodents, and in human skeletal muscle. When considering intramuscular concentrations of ketone bodies and the presence of other carbohydrate and lipid substrates, biological rates of mitochondrial respiration supported by ketone bodies are predicted to be minimal. At the mitochondrial level, it is therefore unlikely that ketone bodies are an important source for energy production in cardiac and skeletal muscle, particularly when other substrates are readily available.nnABSTRACT: Ketone bodies (KB) have recently gained popularity as an alternative fuel source to support mitochondrial oxidative phosphorylation and enhance exercise performance. However, given the low activity of ketolytic enzymes and potential inhibition from carbohydrate oxidation, it remains unknown if KBs can contribute to energy production. We therefore determined the ability of KBs (sodium dl-β-hydroxybutyrate, β-HB; lithium acetoacetate, AcAc) to stimulate in vitro mitochondrial respiration in the left ventricle (LV) and red gastrocnemius (RG) of rats, and in human vastus lateralis. Compared to pyruvate, the ability of KBs to maximally drive respiration was low in isolated mitochondria and permeabilized fibres (PmFb) from the LV (∼30-35% of pyruvate), RG (∼10-30%), and human vastus lateralis (∼2-10%). In PmFb, the concentration of KBs required to half-maximally drive respiration (LV: 889 µm β-HB, 801 µm AcAc; RG: 782 µm β-HB, 267 µm AcAc) were greater than KB content representative of the muscle microenvironment (∼100 µm). This would predict low rates (∼1-4% of pyruvate) of biological KB-supported respiration in the LV (8-14 pmol s mg ) and RG (3-6 pmol s mg ) at rest and following exercise. Moreover, KBs did not increase respiration in the presence of saturating pyruvate, submaximal pyruvate (100 µm) reduced the ability of physiological β-HB to drive respiration, and addition of other intracellular substrates (succinate + palmitoylcarnitine) decreased maximal KB-supported respiration. As a result, product inhibition is likely to limit KB oxidation. Altogether, the ability of KBs to drive mitochondrial respiration is minimal and they are likely to be outcompeted by other substrates, compromising their use as an important energy source.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid32651634,

title = {Intermittent versus continuous enteral nutrition attenuates increases in insulin and leptin during short-term bed rest},

author = {Javier T Gonzalez and Marlou L Dirks and Andrew M Holwerda and Imre W K Kouw and Luc J C van Loon},

doi = {10.1007/s00421-020-04431-4},

issn = {1439-6327},

year  = {2020},

date = {2020-09-01},

journal = {Eur J Appl Physiol},

volume = {120},

number = {9},

pages = {2083--2094},

abstract = {PURPOSE: To compare endocrine responses to intermittent vs continuous enteral nutrition provision during short-term bed rest.nnMETHODS: Twenty healthy men underwent 7 days of bed rest, during which they were randomized to receive enteral nutrition (47%E as carbohydrate, 34%E as fat, 16%E as protein and 3%E as fibre) in a continuous (CONTINUOUS; n = 10; 24 h day at a constant rate) or intermittent (INTERMITTENT; n = 10; as 4 meals per day separated by 5 h) pattern. Daily plasma samples were taken every morning to assess metabolite/hormone concentrations.nnRESULTS: During bed rest, plasma leptin concentrations were elevated to a lesser extent with INTERMITTENT vs CONTINUOUS (iAUC: 0.42 ± 0.38 vs 0.95 ± 0.48 nmol L, respectively; P = 0.014) as were insulin concentrations (interaction effect, P < 0.001) which reached a peak of 369 ± 225 pmol L in CONTINUOUS, compared to 94 ± 38 pmol L in INTERMITTENT (P = 0.001). Changes in glucose infusion rate were positively correlated with changes in fasting plasma GLP-1 concentrations (r = 0.44, P = 0.049).nnCONCLUSION: Intermittent enteral nutrition attenuates the progressive rise in plasma leptin and insulinemia seen with continuous feeding during bed rest, suggesting that continuous feeding increases insulin requirements to maintain euglycemia. This raises the possibility that hepatic insulin sensitivity is impaired to a greater extent with continuous versus intermittent feeding during bed rest. To attenuate endocrine and metabolic changes with enteral feeding, an intermittent feeding strategy may, therefore, be preferable to continuous provision of nutrition. This trial was registered on clinicaltrials.gov as NCT02521025.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid32195768,

title = {Casein Ingestion Does Not Increase Muscle Connective Tissue Protein Synthesis Rates},

author = {Jorn Trommelen and Andrew M Holwerda and Joan M Senden and Joy P B Goessens and Janneau VAN Kranenburg and Annemie P Gijsen and Lex B Verdijk and Luc J C VAN Loon},

doi = {10.1249/MSS.0000000000002337},

issn = {1530-0315},

year  = {2020},

date = {2020-09-01},

journal = {Med Sci Sports Exerc},

volume = {52},

number = {9},

pages = {1983--1991},

abstract = {PURPOSE: This study aimed to assess the effect of dietary protein ingestion on intramuscular connective tissue protein synthesis rates during overnight recovery from a single bout of resistance exercise.nnMETHODS: Thirty-six healthy, young males were randomly assigned to one of three treatments. One group ingested 30 g intrinsically L-[1-C]-phenylalanine-labeled casein protein before sleep (PRO, n = 12). The other two groups performed a bout of resistance exercise in the evening and ingested either placebo (EX, n = 12) or 30 g intrinsically L-[1-C]-phenylalanine-labeled casein protein before sleep (EX + PRO, n = 12). Continuous intravenous infusions of L-[ring-H5]-phenylalanine and L-[1-C]-leucine were applied, and blood and muscle tissue samples were collected to assess connective tissue protein synthesis rates and dietary protein-derived amino acid incorporation in the connective tissue protein fraction.nnRESULTS: Resistance exercise resulted in higher connective tissue protein synthesis rates when compared with rest (0.086 ± 0.017%·h [EX] and 0.080 ± 0.019%·h [EX + PRO] vs 0.059 ± 0.016%·h [PRO]; P < 0.05). Postexercise casein protein ingestion did not result in higher connective tissue protein synthesis rates when compared with postexercise placebo ingestion (P = 1.00). Dietary protein-derived amino acids were incorporated into the connective tissue protein fraction at rest, and to a greater extent during recovery from exercise (P = 0.002).nnCONCLUSION: Resistance exercise increases intramuscular connective tissue protein synthesis rates during overnight sleep, with no further effect of postexercise protein ingestion. However, dietary protein-derived amino acids are being used as precursors to support de novo connective tissue protein synthesis.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid32578906,

title = {During Hospitalization, Older Patients at Risk for Malnutrition Consume <0.65 Grams of Protein per Kilogram Body Weight per Day},

author = {Michelle E G Weijzen and Imre W K Kouw and Phil Geerlings and Lex B Verdijk and Luc J C van Loon},

doi = {10.1002/ncp.10542},

issn = {1941-2452},

year  = {2020},

date = {2020-08-01},

journal = {Nutr Clin Pract},

volume = {35},

number = {4},

pages = {655--663},

abstract = {BACKGROUND: Malnutrition is prevalent in hospitalized patients. To support muscle maintenance in older and chronically ill patients, a protein intake of 1.2-1.5 g/kg/d has been recommended during hospitalization. We assessed daily protein intake levels and distribution in older patients at risk for malnutrition during hospitalization.nnMETHODS: In this prospective, observational study, we measured actual food and food supplement consumption in patients (n = 102; age, 68 ± 14 years; hospital stay, 14 [8-28] days) at risk of malnutrition during hospitalization. Food provided by hospital meals, ONS, and snacks and the actual amount of food (not) consumed were weighed and recorded for all patients.nnRESULTS: Hospital meals provided 1.03 [0.77-1.26] protein, whereas actual protein consumption was only 0.65 [0.37-0.93] g/kg/d. Protein intake at breakfast, lunch, and dinner was 10 [6-15], 9 [5-14], and 13 [9-18] g, respectively. The use of ONS (n = 62) resulted in greater energy (1.26 [0.40-1.79] MJ/d, 300 [100-430] kcal/d) and protein intake levels (11 [4-16] g/d), without changing the macronutrient composition of the diet.nnCONCLUSION: Despite protein provision of ∼1.0 g/kg/d, protein intake remains well below these values (∼0.65 g/kg/d), as 30%-40% of the provided food and supplements is not consumed. Provision of ONS may increase energy and protein intake but does not change the macronutrient composition of the diet. Current nutrition strategies to achieve the recommended daily protein intake in older patients during their hospitalization are not as effective as generally assumed.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid32386891,

title = {A Nitrate-Rich Vegetable Intervention Elevates Plasma Nitrate and Nitrite Concentrations and Reduces Blood Pressure in Healthy Young Adults},

author = {Cindy M T Avoort and Kristin L Jonvik and Jean Nyakayiru and Luc J C Loon and Maria T E Hopman and Lex B Verdijk},

doi = {10.1016/j.jand.2020.02.014},

issn = {2212-2672},

year  = {2020},

date = {2020-08-01},

journal = {Journal of the Academy of Nutrition and Dietetics},

volume = {120},

number = {8},

pages = {1305–1317},

abstract = {BACKGROUND: Emerging evidence suggests that increasing dietary nitrate intake may be an effective approach to reduce blood pressure. Beetroot juice is often used to supplement dietary nitrate, whereas nitrate intake levels from habitual diet are low. An increase in the habitual intake of nitrate-rich vegetables may represent an alternative to nitrate supplementation. However, the effectiveness and acceptability of a nitrate-rich-vegetables diet remain to be established.nnOBJECTIVE: The aim was to investigate the effect and feasibility of two different intervention strategies to increase dietary nitrate intake, on plasma nitrate/nitrite concentrations and blood pressure.nnDESIGN: A randomized, crossover trial was used.nnPARTICIPANTS: Participants were healthy men and women (both n=15; age: 24±6 years) from the Netherlands.nnINTERVENTION: Participants were instructed to consume $sim$400 mg nitrate at lunch, provided through nitrate-rich vegetables and dietary counseling, or beetroot juice supplementation. Both interventions lasted 1 week, with 1-week washout (January to April 2017).nnMAIN OUTCOME: Plasma nitrate and nitrite concentrations and resting systolic and diastolic blood pressure were measured in an overnight fasted state (before and after intervention) and $sim$2.5 hours after lunch (before and throughout intervention on day 1, 4, and 7).nnSTATISTICAL ANALYSIS: Two-factor (time × treatment) repeated-measures analyses of variance were performed.nnRESULTS: Mean plasma nitrate concentrations increased with both interventions, with a larger increase in beetroot juice vs nitrate-rich vegetables, both in a fasted state and $sim$2.5 hours after lunch (day 1, beetroot juice: 2.31±0.56 mg/dL [373±90 μmol/L] vs nitrate-rich vegetables: 1.71±0.83 mg/dL [277±134 μmol/L]; P¡0.001). Likewise, mean plasma nitrite concentrations increased with both interventions, but were higher after lunch in beetroot juice than in nitrate-rich vegetables (day 1: 2.58±1.52 μg/dL [560±331 nmol/L] vs 2.15±1.21 μg/dL [468±263 nmol/L]; P=0.020). Fasting mean systolic and diastolic blood pressure did not change, but mean systolic and diastolic blood pressure assessed $sim$2.5 hours after lunch were significantly reduced throughout both intervention periods (P¡0.05), with no differences between beetroot juice and nitrate-rich vegetables (day 1, systolic blood pressure: -5.1±9.5 mm Hg and diastolic blood pressure: -5.3±8.9 mm Hg).nnCONCLUSION: Short-term consumption of dietary nitrate in the form of nitrate-rich vegetables represents an effective means to increase plasma nitrate and nitrite concentrations, and reduces blood pressure to the same extent as beetroot juice supplementation.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}