All Publications

@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.},

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@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.},

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@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.},

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@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.},

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@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.},

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@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.},

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@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.},

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@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.},

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@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}

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@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.},

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tppubtype = {article}

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@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).},

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@article{Betts2020,

title = {PRESENT 2020: Texto que desarrolla la lista de verificación para el adecuado informe de la evidencia en ensayos clínicos de deporte y nutrición del ejercicio (Traducción Inglés-Español)},

author = {JA Betts and JT González and LM Burke and GL Close and I Garthe and LJ James and AE Jeukendrup and LP Morton and DC Nieman and P Peeling and SM Phillips and T Stellingwerff and LJC Van Loon and C Williams and K Woolf and RJ Maughan and G Atkinson and Traductor: ME Da Silva-Grigoletto and Traductor: F Boscolo Del Vecchio and Traductor: Juan de Dios Beas Jiménez},

doi = {10.33155/j.ramd.2020.11.004},

issn = {2172-5063},

year  = {2020},

date = {2020-12-01},

journal = {Rev And Med Dep},

volume = {13},

number = {4},

pages = {244--254},

publisher = {Centro Andaluz de Medicina del Deporte},

abstract = {PRESENT 2020: Texto que desarrolla la lista de verificación para el adecuado informe de la evidencia en ensayos clínicos de deporte y nutrición del ejercicio (Traducción Inglés-Español).


Traducido por:





 ME Da Silva-Grigoletto   Grupo de entrenamiento funcional. Universidad Federal de Sergipe. São Cristovão. Brasil 


 F Boscolo Del Vecchio   Escuela de Educación Física. Universidad Federal de Pelotas. Pelotas. Brasil 


 Juan de Dios Beas Jiménez   Centro Andaluz de Medicina del Deporte. Sevilla. España. 





 },

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@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},

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

issn = {1179-2035},

year  = {2020},

date = {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.},

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tppubtype = {article}

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@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}

}

@article{pmid32359142,

title = {Dose-response effects of dietary protein on muscle protein synthesis during recovery from endurance exercise in young men: a double-blind randomized trial},

author = {Tyler A Churchward-Venne and Philippe J M Pinckaers and Joey S J Smeets and Milan W Betz and Joan M Senden and Joy P B Goessens and Annemie P Gijsen and Ian Rollo and Lex B Verdijk and Luc J C van Loon},

doi = {10.1093/ajcn/nqaa073},

issn = {1938-3207},

year  = {2020},

date = {2020-08-01},

journal = {Am J Clin Nutr},

volume = {112},

number = {2},

pages = {303--317},

abstract = {BACKGROUND: Protein ingestion increases skeletal muscle protein synthesis rates during recovery from endurance exercise.nnOBJECTIVES: We aimed to determine the effect of graded doses of dietary protein co-ingested with carbohydrate on whole-body protein metabolism, and skeletal muscle myofibrillar (MyoPS) and mitochondrial (MitoPS) protein synthesis rates during recovery from endurance exercise.nnMETHODS: In a randomized, double-blind, parallel-group design, 48 healthy, young, endurance-trained men (mean ± SEM age: 27 ± 1 y) received a primed continuous infusion of l-[ring-2H5]-phenylalanine, l-[ring-3,5-2H2]-tyrosine, and l-[1-13C]-leucine and ingested 45 g carbohydrate with either 0 (0 g PRO), 15 (15 g PRO), 30 (30 g PRO), or 45 (45 g PRO) g intrinsically l-[1-13C]-phenylalanine and l-[1-13C]-leucine labeled milk protein after endurance exercise. Blood and muscle biopsy samples were collected over 360 min of postexercise recovery to assess whole-body protein metabolism and both MyoPS and MitoPS rates.nnRESULTS: Protein intake resulted in ∼70%-74% of the ingested protein-derived phenylalanine appearing in the circulation. Whole-body net protein balance increased dose-dependently after ingestion of 0, 15, 30, or 45 g protein (mean ± SEM: -0.31± 0.16, 5.08 ± 0.21, 10.04 ± 0.30, and 13.49 ± 0.55 μmol phenylalanine · kg-1 · h-1, respectively; P < 0.001). 30 g PRO stimulated a ∼46% increase in MyoPS rates (%/h) compared with 0 g PRO and was sufficient to maximize MyoPS rates after endurance exercise. MitoPS rates were not increased after protein ingestion; however, incorporation of dietary protein-derived l-[1-13C]-phenylalanine into de novo mitochondrial protein increased dose-dependently after ingestion of 15, 30, and 45 g protein at 360 min postexercise (0.018 ± 0.002, 0.034 ± 0.002, and 0.046 ± 0.003 mole percentage excess, respectively; P < 0.001).nnCONCLUSIONS: Protein ingested after endurance exercise is efficiently digested and absorbed into the circulation. Whole-body net protein balance and dietary protein-derived amino acid incorporation into mitochondrial protein respond to increasing protein intake in a dose-dependent manner. Ingestion of 30 g protein is sufficient to maximize MyoPS rates during recovery from a single bout of endurance exercise.This trial was registered at trialregister.nl as NTR5111.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid32069356,

title = {Protein Type, Protein Dose, and Age Modulate Dietary Protein Digestion and Phenylalanine Absorption Kinetics and Plasma Phenylalanine Availability in Humans},

author = {Stefan H M Gorissen and Jorn Trommelen and Imre W K Kouw and Andrew M Holwerda and Bart Pennings and Bart B L Groen and Benjamin T Wall and Tyler A Churchward-Venne and Astrid M H Horstman and René Koopman and Nicholas A Burd and Cas J Fuchs and Marlou L Dirks and Peter T Res and Joan M G Senden and Jan M J M Steijns and Lisette C P G M de Groot and Lex B Verdijk and Luc J C van Loon},

doi = {10.1093/jn/nxaa024},

issn = {1541-6100},

year  = {2020},

date = {2020-08-01},

journal = {J Nutr},

volume = {150},

number = {8},

pages = {2041--2050},

abstract = {BACKGROUND: Dietary protein ingestion stimulates muscle protein synthesis by providing amino acids to the muscle. The magnitude and duration of the postprandial increase in muscle protein synthesis rates are largely determined by dietary protein digestion and amino acid absorption kinetics.nnOBJECTIVE: We assessed the impact of protein type, protein dose, and age on dietary protein digestion and amino acid absorption kinetics in vivo in humans.nnMETHODS: We included data from 18 randomized controlled trials with a total of 602 participants [age: 53 ± 23 y; BMI (kg/m2): 24.8 ± 3.3] who consumed various quantities of intrinsically l-[1-13C]-phenylalanine-labeled whey (n = 137), casein (n = 393), or milk (n = 72) protein and received intravenous infusions of l-[ring-2H5]-phenylalanine, which allowed us to assess protein digestion and phenylalanine absorption kinetics and the postprandial release of dietary protein-derived phenylalanine into the circulation. The effect of aging on these processes was assessed in a subset of 82 young (aged 22 ± 3 y) and 83 older (aged 71 ± 5 y) individuals.nnRESULTS: A total of 50% ± 14% of dietary protein-derived phenylalanine appeared in the circulation over a 5-h postprandial period. Casein ingestion resulted in a smaller (45% ± 11%), whey protein ingestion in an intermediate (57% ± 10%), and milk protein ingestion in a greater (65% ± 13%) fraction of dietary protein-derived phenylalanine appearing in the circulation (P < 0.001). The postprandial availability of dietary protein-derived phenylalanine in the circulation increased with the ingestion of greater protein doses (P < 0.05). Protein digestion and phenylalanine absorption kinetics were attenuated in older when compared with young individuals, with 45% ± 10% vs. 51% ± 14% of dietary protein-derived phenylalanine appearing in the circulation, respectively (P = 0.001).nnCONCLUSIONS: Protein type, protein dose, and age modulate dietary protein digestion and amino acid absorption kinetics and subsequent postprandial plasma amino acid availability in vivo in humans. These trials were registered at clinicaltrials.gov as NCT00557388, NCT00936039, NCT00991523, NCT01317511, NCT01473576, NCT01576848, NCT01578590, NCT01615276, NCT01680146, NCT01820975, NCT01986842, and NCT02596542, and at http://www.trialregister.nl as NTR3638, NTR3885, NTR4060, NTR4429, and NTR4492.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid32751788,

title = {Casein Protein Processing Strongly Modulates Post-Prandial Plasma Amino Acid Responses In Vivo in Humans},

author = {Jorn Trommelen and Michelle E G Weijzen and Janneau van Kranenburg and Renate A Ganzevles and Milou Beelen and Lex B Verdijk and Luc J C van Loon},

doi = {10.3390/nu12082299},

issn = {2072-6643},

year  = {2020},

date = {2020-07-01},

journal = {Nutrients},

volume = {12},

number = {8},

abstract = {Micellar casein is characterized as a slowly digestible protein source, and its structure can be modulated by various food processing techniques to modify its functional properties. However, little is known about the impact of such modifications on casein protein digestion and amino acid absorption kinetics and the subsequent post-prandial plasma amino acid responses. In the present study, we determined post-prandial aminoacidemia following ingestion of isonitrogenous amounts of casein protein (40 g) provided as micellar casein (Mi-CAS), calcium caseinate (Ca-CAS), or cross-linked sodium caseinate (XL-CAS). Fifteen healthy, young men (age: 26 ± 4 years, BMI: 23 ± 1 kg·m) participated in this randomized cross-over study and ingested 40 g Mi-Cas, Ca-CAS, and XL-CAS protein, with a ~1 week washout between treatments. On each trial day, arterialized blood samples were collected at regular intervals during a 6 h post-prandial period to assess plasma amino acid concentrations using ultra-performance liquid chromatography. Plasma amino acid concentrations were higher following the ingestion of XL-CAS when compared to Mi-CAS and Ca-CAS from t = 15 to 90 min (all  < 0.05). Plasma amino acid concentrations were higher following ingestion of Mi-CAS compared to Ca-CAS from t = 30 to 45 min (both  < 0.05). Plasma total amino acids iAUC were higher following the ingestion of XL-CAS when compared to Ca-CAS (294 ± 63 vs. 260 ± 75 mmol·L,  = 0.006), with intermediate values following Mi-CAS ingestion (270 ± 63 mmol·L,  > 0.05). In conclusion, cross-linked sodium caseinate is more rapidly digested when compared to micellar casein and calcium caseinate. Protein processing can strongly modulate the post-prandial rise in plasma amino acid bioavailability in vivo in humans.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid32175681,

title = {The concept of skeletal muscle memory: Evidence from animal and human studies},

author = {Tim Snijders and Thorben Aussieker and Andy Holwerda and Gianni Parise and Luc J C van Loon and Lex B Verdijk},

doi = {10.1111/apha.13465},

issn = {1748-1716},

year  = {2020},

date = {2020-07-01},

journal = {Acta Physiol (Oxf)},

volume = {229},

number = {3},

pages = {e13465},

abstract = {Within the current paradigm of the myonuclear domain theory, it is postulated that a linear relationship exists between muscle fibre size and myonuclear content. The myonuclear domain is kept (relatively) constant by adding additional nuclei (supplied by muscle satellite cells) during muscle fibre hypertrophy and nuclear loss (by apoptosis) during muscle fibre atrophy. However, data from recent animal studies suggest that myonuclei that are added to support muscle fibre hypertrophy are not lost within various muscle atrophy models. Such myonuclear permanence has been suggested to constitute a mechanism allowing the muscle fibre to (re)grow more efficiently during retraining, a phenomenon referred to as "muscle memory." The concept of "muscle memory by myonuclear permanence" has mainly been based on data attained from rodent experimental models. Whether the postulated mechanism also holds true in humans remains largely ambiguous. Nevertheless, there are several studies in humans that provide evidence to potentially support or contradict (parts of) the muscle memory hypothesis. The goal of the present review was to discuss the evidence for the existence of "muscle memory" in both animal and human models of muscle fibre hypertrophy as well as atrophy. Furthermore, to provide additional insight in the potential presence of muscle memory by myonuclear permanence in humans, we present new data on previously performed exercise training studies. Finally, suggestions for future research are provided to establish whether muscle memory really exists in humans.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid32224084,

title = {Could intramuscular storage of dietary nitrate contribute to its ergogenic effect? A mini-review},

author = {Jean Nyakayiru and Luc J C van Loon and Lex B Verdijk},

doi = {10.1016/j.freeradbiomed.2020.03.025},

issn = {1873-4596},

year  = {2020},

date = {2020-05-01},

journal = {Free Radic Biol Med},

volume = {152},

pages = {295--300},

abstract = {Extensive research performed over the past 10 years has resulted in dietary nitrate being considered a nutritional supplement that can improve exercise performance. However, there is still limited insight in the metabolic fate of dietary nitrate following the appearance of nitrate and nitrite in the circulation. Recent observations in humans suggest the storage of nitrate in skeletal muscle tissue. This short review discusses the possibility of nitrate being stored and utilized in human skeletal muscle tissue, and why confirming this may increase our understanding of how the nitrate-nitrite-NO pathway improves exercise performance. Further insight in skeletal muscle nitrate storage and metabolism may provide answers to current gaps in knowledge, such as the ergogenic benefit of acute vs multiday dietary nitrate supplementation, as well as the suggested muscle fiber-type specific effects on exercise performance. In this mini-review, specific questions that need further exploration are also discussed.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid32006029,

title = {End-Stage Renal Disease Patients Lose a Substantial Amount of Amino Acids during Hemodialysis},

author = {Floris K Hendriks and Joey S J Smeets and Natascha J H Broers and Janneau M X van Kranenburg and Frank M van der Sande and Jeroen P Kooman and Luc J C van Loon},

doi = {10.1093/jn/nxaa010},

issn = {1541-6100},

year  = {2020},

date = {2020-05-01},

journal = {J Nutr},

volume = {150},

number = {5},

pages = {1160--1166},

abstract = {BACKGROUND: Poor nutritional status is frequently observed in end-stage renal disease patients and associated with adverse clinical outcomes and increased mortality. Loss of amino acids (AAs) during hemodialysis (HD) may contribute to protein malnutrition in these patients.nnOBJECTIVE: We aimed to assess the extent of AA loss during HD in end-stage renal disease patients consuming their habitual diet.nnMETHODS: Ten anuric chronic HD patients (mean ± SD age: 67.9 ± 19.3 y, BMI: 23.2 ± 3.5 kg/m2), undergoing HD 3 times per week, were selected to participate in this study. Spent dialysate was collected continuously and plasma samples were obtained directly before and after a single HD session in each participant. AA profiles in spent dialysate and in pre-HD and post-HD plasma were measured through ultra-performance liquid chromatography to determine AA concentrations and, as such, net loss of AAs. In addition, dietary intake before and throughout HD was assessed using a 24-h food recall questionnaire during HD. Paired-sample t tests were conducted to compare pre-HD and post-HD plasma AA concentrations.nnRESULTS: During an HD session, 11.95 ± 0.69 g AAs were lost via the dialysate, of which 8.26 ± 0.46 g were nonessential AAs, 3.69 ± 0.31 g were essential AAs, and 1.64 ± 0.17 g were branched-chain AAs. As a consequence, plasma total and essential AA concentrations declined significantly from 2.88 ± 0.15 and 0.80 ± 0.05 mmol/L to 2.27 ± 0.11 and 0.66 ± 0.05 mmol/L, respectively (P < 0.05). AA profiles of pre-HD plasma and spent dialysate were similar. Moreover, AA concentrations in pre-HD plasma and spent dialysate were strongly correlated (Spearman's ρ = 0.92, P < 0.001).nnCONCLUSIONS: During a single HD session, ∼12 g AAs are lost into the dialysate, causing a significant decline in plasma AA concentrations. AA loss during HD can contribute substantially to protein malnutrition in end-stage renal disease patients. This study was registered at the Netherlands Trial Registry (NTR7101).},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid31641211,

title = {Mitochondrial DNA copy number associates with insulin sensitivity and aerobic capacity, and differs between sedentary, overweight middle-aged males with and without type 2 diabetes},

author = {Dumitru Constantin-Teodosiu and Despina Constantin and Maurice M Pelsers and Lex B Verdijk and Luc van Loon and Paul L Greenhaff},

doi = {10.1038/s41366-019-0473-2},

issn = {1476-5497},

year  = {2020},

date = {2020-04-01},

journal = {Int J Obes (Lond)},

volume = {44},

number = {4},

pages = {929--936},

abstract = {BACKGROUND/OBJECTIVES: Increased risk of type 2 diabetes mellitus (T2DM) is linked to impaired muscle mitochondrial function and reduced mitochondrial DNA copy number (mtDNA). However, studies have failed to control for habitual physical activity levels, which directly influences both mtDNA copy number and insulin sensitivity. We, therefore, examined whether physical conditioning status (maximal oxygen uptake, V̇O) was associated with skeletal muscle mitochondrial volume and mtDNA, and was predictive of T2DM in overweight, middle-aged men.nnMETHODS: Whole-body physiological (ISI-insulin sensitivity index, HOMA-IR, V̇O) and muscle biochemical/molecular (vastus lateralis; mtDNA, mitochondrial and glycolytic enzymes activity, lipid content and markers of lipid peroxidation) measurements were performed in three groups of overweight, middle-aged male volunteers (n = 10 per group): sedentary T2DM (ST2DM); sedentary control (SC) and non-sedentary control (NSC), who differed in aerobic capacity (ST2DM < SC < NSC).nnRESULTS: mtDNA was greater in NSC versus SC and ST2DM (P < 0.001; P < 0.001), and less in ST2DM versus SC (P < 0.01). Across all groups, mtDNA positively correlated with ISI (P < 0.001; r = 0.688) and V̇O (normalised to free fat mass; r = 0.684, P < 0.001), and negatively correlated to HOMA-IR (r = -0.544, P < 0.01). The activity of mitochondrial enzymes (GluDH, CS and β-HAD) was greater in NSC than ST2DM (P < 0.01, P < 0.001 and P < 0.05) and SC (P < 0.05, P < 0.01 and P < 0.05), but similar between ST2DM and SC. Intramuscular-free fatty acids, triglycerides and malondialdehyde contents were similar between ST2DM and SC.nnCONCLUSIONS: Body composition and indices of muscle mitochondrial volume/function were similar between SC and ST2DM. However, mtDNA differed and was positively associated with ISI, HOMA-IR and V̇O across all groups. Collectively, the findings support the contention that habitual physical activity is a key component of T2DM development, possibly by influencing mtDNA.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid32191599,

title = {Hot-water immersion does not increase postprandial muscle protein synthesis rates during recovery from resistance-type exercise in healthy, young males},

author = {Cas J Fuchs and Joey S J Smeets and Joan M Senden and Antoine H Zorenc and Joy P B Goessens and Wouter D van Marken Lichtenbelt and Lex B Verdijk and Luc J C van Loon},

doi = {10.1152/japplphysiol.00836.2019},

issn = {1522-1601},

year  = {2020},

date = {2020-04-01},

journal = {J Appl Physiol (1985)},

volume = {128},

number = {4},

pages = {1012--1022},

abstract = {The purpose of this study was to assess the impact of postexercise hot-water immersion on postprandial myofibrillar protein synthesis rates during recovery from a single bout of resistance-type exercise in healthy, young men. Twelve healthy, adult men (age: 23 ± 1 y) performed a single bout of resistance-type exercise followed by 20 min of water immersion of both legs. One leg was immersed in hot water [46°C: hot-water immersion (HWI)], while the other leg was immersed in thermoneutral water (30°C: CON). After water immersion, a beverage was ingested containing 20 g intrinsically L-[1-C]-phenylalanine and L-[1-C]-leucine labeled milk protein with 45 g of carbohydrates. In addition, primed continuous L-[-H]-phenylalanine and L-[1-C]-leucine infusions were applied, with frequent collection of blood and muscle samples to assess myofibrillar protein synthesis rates in vivo over a 5-h recovery period. Muscle temperature immediately after water immersion was higher in the HWI compared with the CON leg (37.5 ± 0.1 vs. 35.2 ± 0.2°C;  < 0.001). Incorporation of dietary protein-derived L-[1-C]-phenylalanine into myofibrillar protein did not differ between the HWI and CON leg during the 5-h recovery period (0.025 ± 0.003 vs. 0.024 ± 0.002 MPE;  = 0.953). Postexercise myofibrillar protein synthesis rates did not differ between the HWI and CON leg based upon L-[1-C]-leucine (0.050 ± 0.005 vs. 0.049 ± 0.002%/h;  = 0.815) and L-[-H]-phenylalanine (0.048 ± 0.002 vs. 0.047 ± 0.003%/h;  = 0.877), respectively. Hot-water immersion during recovery from resistance-type exercise does not increase the postprandial rise in myofibrillar protein synthesis rates. In addition, postexercise hot-water immersion does not increase the capacity of the muscle to incorporate dietary protein-derived amino acids in muscle tissue protein during subsequent recovery. This is the first study to assess the effect of postexercise hot-water immersion on postprandial myofibrillar protein synthesis rates and the incorporation of dietary protein-derived amino acids into muscle protein. We observed that hot-water immersion during recovery from a single bout of resistance-type exercise does not further increase myofibrillar protein synthesis rates or augment the postprandial incorporation of dietary protein-derived amino acids in muscle throughout 5 h of postexercise recovery.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid31728607,

title = {Impact of whole dairy matrix on musculoskeletal health and aging-current knowledge and research gaps},

author = {N R W Geiker and C Mølgaard and S Iuliano and R Rizzoli and Y Manios and L J C van Loon and J-M Lecerf and G Moschonis and J-Y Reginster and I Givens and A Astrup},

doi = {10.1007/s00198-019-05229-7},

issn = {1433-2965},

year  = {2020},

date = {2020-04-01},

journal = {Osteoporos Int},

volume = {31},

number = {4},

pages = {601--615},

abstract = {Dairy products are included in dietary guidelines worldwide, as milk, yoghurt, and cheese are good sources of calcium and protein, vital nutrients for bones and muscle mass maintenance. Bone growth and mineralization occur during infancy and childhood, peak bone mass being attained after early adulthood. A low peak bone mass has consequences later in life, including increased risk of osteoporosis and fractures. Currently, more than 200 million people worldwide suffer from osteoporosis, with approximately 9 million fractures yearly. This poses a tremendous economic burden on health care. Between 5% and 10% of the elderly suffer from sarcopenia, the loss of muscle mass and strength, further increasing the risk of fractures due to falls. Evidence from interventional and observational studies support that fermented dairy products in particular exert beneficial effects on bone growth and mineralization, attenuation of bone loss, and reduce fracture risk. The effect cannot be explained by single nutrients in dairy, which suggests that a combined or matrix effect may be responsible similar to the matrix effects of foods on cardiometabolic health. Recently, several plant-based beverages and products have become available and marketed as substitutes for dairy products, even though their nutrient content differs substantially from dairy. Some of these products have been fortified, in efforts to mimic the nutritional profile of milk, but it is unknown whether the additives have the same bioavailability and beneficial effect as dairy. We conclude that the dairy matrix exerts an effect on bone and muscle health that is more than the sum of its nutrients, and we suggest that whole foods, not only single nutrients, need to be assessed in future observational and intervention studies of health outcomes. Furthermore, the importance of the matrix effect on health outcomes argues in favor of making future dietary guidelines food based.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid31688656,

title = {Temporal Muscle-specific Disuse Atrophy during One Week of Leg Immobilization},

author = {Sean P Kilroe and Jonathan Fulford and Sarah R Jackman and Luc J C VAN Loon and Benjamin T Wall},

doi = {10.1249/MSS.0000000000002200},

issn = {1530-0315},

year  = {2020},

date = {2020-04-01},

journal = {Med Sci Sports Exerc},

volume = {52},

number = {4},

pages = {944--954},

abstract = {PURPOSE: Musculoskeletal injuries necessitate periods of disuse (i.e., limb immobilization) during which rapid skeletal muscle atrophy occurs. The relative susceptibility of different muscles of the thigh to disuse atrophy remains uninvestigated. We assessed muscle disuse atrophy of individual thigh muscles throughout 1 wk of unilateral knee immobilization.nnMETHODS: Thirteen healthy, young (20.2 ± 0.6 yr) men underwent 7 d of unilateral leg immobilization via knee bracing. Magnetic resonance imaging scans were performed bilaterally prior to, and following 2 and 7 d of immobilization to determine the volume and anatomical cross-sectional area of the individual muscle groups of the upper legs.nnRESULTS: In contrast to the control leg, total thigh muscle volume had decreased by 1.7% ± 0.3% (P < 0.01) and 5.5% ± 0.6% (P < 0.001) in the immobilized leg after 2 and 7 d of disuse, respectively. Muscle loss was significantly greater in the Musculus quadriceps (day 2; 1.7% ± 0.3% (P < 0.05) and day 7; 6.7% ± 0.6%) when compared with the Musculus hamstrings (day 2; 1.4% ± 0.2% (P < 0.01) and day 7; 3.5% ± 0.3%) after 7 d of disuse (P < 0.001). Individual muscles of the thigh exhibited different atrophy rates with the Musculus vastus lateralis anatomical cross-sectional area showing the greater (2.6% ± 0.4% and 7.2% ± 0.8%), and the Musculus gracilis the lesser (1.1% ± 0.7% and 2.3% ± 1.0%) decline following 2 and 7 d of immobilization, respectively (P < 0.01).nnCONCLUSIONS: Thigh muscle disuse atrophy occurs rapidly and is already evident within 2 d of leg immobilization and progresses at a similar rate over the next 5 d (~0.8% muscle loss per day). M. quadriceps muscle shows more atrophy when compared with the M. hamstrings.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid31727194,

title = {The glycation level of milk protein strongly modulates post-prandial lysine availability in humans},

author = {Jean Nyakayiru and Glenn A A van Lieshout and Jorn Trommelen and Janneau van Kranenburg and Lex B Verdijk and Marjolijn C E Bragt and Luc J C van Loon},

doi = {10.1017/S0007114519002927},

issn = {1475-2662},

year  = {2020},

date = {2020-03-01},

journal = {Br J Nutr},

volume = {123},

number = {5},

pages = {545--552},

abstract = {Industrial heat treatment of milk results in protein glycation. A high protein glycation level has been suggested to compromise the post-prandial rise in plasma amino acid availability following protein ingestion. In the present study, we assessed the impact of glycation level of milk protein on post-prandial plasma amino acid responses in humans. Fifteen healthy, young men (age 26 (SEM 1) years, BMI 24 (SEM 1) kg/m2) participated in this randomised cross-over study and ingested milk protein powder with protein glycation levels of 3, 20 and 50 % blocked lysine. On each trial day, arterialised blood samples were collected at regular intervals during a 6-h post-prandial period to assess plasma amino acid concentrations using ultra-performance liquid chromatography. Plasma essential amino acid (EAA) concentrations increased following milk protein ingestion, with the 20 and 50 % glycated milk proteins showing lower overall EAA responses compared with the 3 % glycated milk protein (161 (SEM 7) and 142 (SEM 7) v. 178 (SEM 9) mmol/l × 6 h, respectively; P ≤ 0·011). The lower post-prandial plasma amino acid responses were fully attributed to an attenuated post-prandial rise in circulating plasma lysine concentrations. Plasma lysine responses (incremental AUC) following ingestion of the 20 and 50 % glycated milk proteins were 35 (SEM 4) and 92 (SEM 2) % lower compared with the 3 % glycated milk protein (21·3 (SEM 1·4) and 2·8 (SEM 0·7) v. 33·3 (SEM 1·7) mmol/l × 6 h, respectively; P < 0·001). Milk protein glycation lowers post-prandial plasma lysine availability in humans. The lower post-prandial availability of lysine following ingestion of proteins with a high glycation level may compromise the anabolic properties of a protein source.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid32035417,

title = {Endurance-Type Exercise Increases Bulk and Individual Mitochondrial Protein Synthesis Rates in Rats},

author = {Andrew M Holwerda and Freek G Bouwman and Miranda Nabben and Ping Wang and Janneau van Kranenburg and Annemie P Gijsen and Jatin G Burniston and Edwin C M Mariman and Luc J C van Loon},

doi = {10.1123/ijsnem.2019-0281},

issn = {1543-2742},

year  = {2020},

date = {2020-03-01},

journal = {Int J Sport Nutr Exerc Metab},

volume = {30},

number = {2},

pages = {153–164},

abstract = {Physical activity increases muscle protein synthesis rates. However, the impact of exercise on the coordinated up- and/or downregulation of individual protein synthesis rates in skeletal muscle tissue remains unclear. The authors assessed the impact of exercise on mixed muscle, myofibrillar, and mitochondrial protein synthesis rates as well as individual protein synthesis rates in vivo in rats. Adult Lewis rats either remained sedentary (n = 3) or had access to a running wheel (n = 3) for the last 2 weeks of a 3-week experimental period. Deuterated water was injected and subsequently administered in drinking water over the experimental period. Blood and soleus muscle were collected and used to assess bulk mixed muscle, myofibrillar, and mitochondrial protein synthesis rates using gas chromatography-mass spectrometry and individual muscle protein synthesis rates using liquid chromatography-mass spectrometry (i.e., dynamic proteomic profiling). Wheel running resulted in greater myofibrillar (3.94 ± 0.26 vs. 3.03 ± 0.15%/day; p < .01) and mitochondrial (4.64 ± 0.24 vs. 3.97 ± 0.26%/day; p < .05), but not mixed muscle (2.64 ± 0.96 vs. 2.38 ± 0.62%/day; p = .71) protein synthesis rates, when compared with the sedentary condition. Exercise impacted the synthesis rates of 80 proteins, with the difference from the sedentary condition ranging between -64% and +420%. Significantly greater synthesis rates were detected for F1-ATP synthase, ATP synthase subunit alpha, hemoglobin, myosin light chain-6, and synaptopodin-2 (p < .05). The skeletal muscle protein adaptive response to endurance-type exercise involves upregulation of mitochondrial protein synthesis rates, but it is highly coordinated as reflected by the up- and downregulation of various individual proteins across different bulk subcellular protein fractions.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid31910028,

title = {Effect of acute and short-term dietary fat ingestion on postprandial skeletal muscle protein synthesis rates in middle-aged, overweight, and obese men},

author = {Kostas Tsintzas and Robert Jones and Pardeep Pabla and Joanne Mallinson and David A Barrett and Dong-Hyun Kim and Scott Cooper and Amanda Davies and Tariq Taylor and Carolyn Chee and Christopher Gaffney and Luc J C van Loon and Francis B Stephens},

doi = {10.1152/ajpendo.00344.2019},

issn = {1522-1555},

year  = {2020},

date = {2020-03-01},

journal = {Am J Physiol Endocrinol Metab},

volume = {318},

number = {3},

pages = {E417--E429},

abstract = {Muscle anabolic resistance to dietary protein is associated with obesity and insulin resistance. However, the contribution of excess consumption of fat to anabolic resistance is not well studied. The aim of these studies was to test the hypothesis that acute and short-term dietary fat overload will impair the skeletal muscle protein synthetic response to dietary protein ingestion. Eight overweight/obese men [46.4 ± 1.4 yr, body mass index (BMI) 32.3 ± 5.4 kg/m] participated in the acute feeding study, which consisted of two randomized crossover trials. On each occasion, subjects ingested an oral meal (with and without fat emulsion), 4 h before the coingestion of milk protein, intrinsically labeled with [1-C]phenylalanine, and dextrose. Nine overweight/obese men (44.0 ± 1.7 yr, BMI 30.1 ± 1.1 kg/m) participated in the chronic study, which consisted of a baseline, 1-wk isocaloric diet, followed by a 2-wk high-fat diet (+25% energy excess). Acutely, incorporation of dietary amino acids into the skeletal muscle was twofold higher ( < 0.05) in the lipid trial compared with control. There was no effect of prior lipid ingestion on indices of insulin sensitivity (muscle glucose uptake, pyruvate dehydrogenase complex activity, and Akt phosphorylation) in response to the protein/dextrose drink. Fat overfeeding had no effect on muscle protein synthesis or glucose disposal in response to whey protein ingestion, despite increased muscle diacylglycerol C16:0 ( = 0.06) and ceramide C16:0 ( < 0.01) levels. Neither acute nor short-term dietary fat overload has a detrimental effect on the skeletal muscle protein synthetic response to dietary protein ingestion in overweight/obese men, suggesting that dietary-induced accumulation of intramuscular lipids per se is not associated with anabolic resistance.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid31652237,

title = {Impact of Exercise-Nutritional State Interactions in Patients with Type 2 Diabetes},

author = {Kenneth Verboven and Inez Wens and Frank Vandenabeele and A N Stevens and Bert Celie and Bruno Lapauw and Paul Dendale and Luc J C VAN Loon and Patrick Calders and Dominique Hansen},

doi = {10.1249/MSS.0000000000002165},

issn = {1530-0315},

year  = {2020},

date = {2020-03-01},

journal = {Med Sci Sports Exerc},

volume = {52},

number = {3},

pages = {720--728},

abstract = {INTRODUCTION: This study examines the role of nutritional status during exercise training in patients with type 2 diabetes mellitus by investigating the effect of endurance-type exercise training in the fasted versus the fed state on clinical outcome measures, glycemic control, and skeletal muscle characteristics in male type 2 diabetes patients.nnMETHODS: Twenty-five male patients (glycated hemoglobin (HbA1c), 57 ± 3 mmol·mol (7.4% ± 0.3%)) participated in a randomized 12-wk supervised endurance-type exercise intervention, with exercise being performed in an overnight-fasted state (n = 13) or after consuming breakfast (n = 12). Patients were evaluated for glycemic control, blood lipid profiles, body composition and physical fitness, and skeletal muscle gene expression.nnRESULTS: Exercise training was well tolerated without any incident of hypoglycemia. Exercise training significantly decreased whole-body fat mass (-1.6 kg) and increased high-density lipoprotein concentrations (+2 mg·dL), physical fitness (+1.7 mL·min·kg), and fat oxidation during exercise in both groups (PTIME < 0.05), with no between-group differences (PTIME × GROUP > 0.05). HbA1c concentrations significantly decreased after exercise training (PTIME < 0.001), with a significant greater reduction after consuming breakfast (-0.30% ± 0.06%) compared with fasted state (-0.08% ± 0.06%; mean difference, 0.21%; PTIME × GROUP = 0.016). No interaction effects were observed for skeletal muscle genes related to lipid metabolism or oxidative capacity.nnCONCLUSIONS: Endurance-type exercise training in the fasted or fed state do not differ in their efficacy to reduce fat mass, increase fat oxidation capacity, and increase cardiorespiratory fitness and high-density lipoprotein concentrations or their risk of hypoglycemia in male patients with type 2 diabetes. HbA1c seems to be improved more with exercise performed in the postprandial compared with the postabsorptive state.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid32297228,

title = {Multifrequency bioelectrical impedance analysis may represent a reproducible and practical tool to assess skeletal muscle mass in euvolemic acutely ill hospitalized geriatric patients},

author = {Walther M W H Sipers and Jesper Dorge and Jos M G A Schols and Lex B Verdijk and Luc J C van Loon},

doi = {10.1007/s41999-019-00253-6},

issn = {1878-7649},

year  = {2020},

date = {2020-02-01},

journal = {Eur Geriatr Med},

volume = {11},

number = {1},

pages = {155--162},

abstract = {PURPOSE: Geriatric patients with low skeletal muscle mass (SMM) and strength have a poor clinical outcome following acute illness. Consequently, it is recommended to assess SMM and strength in patients admitted to the acute care geriatric ward. Bio-impedance analysis (BIA) is a practical tool to assess SMM in hospitalized patients. However, the reproducibility of this assessment may be compromised due to changing clinical conditions. The objective was to study the reproducibility of SMM assessment using multifrequency BIA (mf-BIA) in acutely ill geriatric patients.nnMETHODS: A total of 47 geriatric patients (age: 83 ± 7 years; n = 31 female) admitted to the acute geriatric ward participated in this pilot study. SMM was assessed on three occasions within the first week of hospital admission using the Maltron Bioscan-920-II.nnRESULTS: Total skeletal SMM averaged 21.4 ± 5.7, 20.7 ± 5.4, and 20.8 ± 5.1 kg assessed at 2 ± 1, 3 ± 1 and 5 ± 2 days after hospital admission, respectively. Coefficient of variation (COV) of the three SMM measurements was 4.9 ± 4.5% with an intraclass correlation coefficient (ICC) of 0.976 (CI 95%: 0.961-0.986; P < 0.001). Hydration status affected the reproducibility of the measurement, with non-euvolemic patients (n = 16) showing a significantly higher COV (7.6 ± 5.9% vs 3.5 ± 2.9%; P < 0.01) and a lower ICC (0.983 vs 0.913; P < 0.001) when compared to the euvolemic patients (n = 31).nnCONCLUSION: Mf-BIA seems a highly reproducible and reliable method to assess SMM throughout the first week of hospitalization in geriatric patients. However, since abnormal hydration status may compromise reliability of the measurement, assessment of SMM using mf-BIA may better be performed when euvolemic status has been established.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid31788800,

title = {Postexercise cooling impairs muscle protein synthesis rates in recreational athletes},

author = {Cas J Fuchs and Imre W K Kouw and Tyler A Churchward-Venne and Joey S J Smeets and Joan M Senden and Wouter D van Marken Lichtenbelt and Lex B Verdijk and Luc J C van Loon},

doi = {10.1113/JP278996},

issn = {1469-7793},

year  = {2020},

date = {2020-02-01},

journal = {J Physiol},

volume = {598},

number = {4},

pages = {755--772},

abstract = {KEY POINTS: Protein ingestion and cooling are strategies employed by athletes to improve postexercise recovery and, as such, to facilitate muscle conditioning. However, whether cooling affects postprandial protein handling and subsequent muscle protein synthesis rates during recovery from exercise has not been assessed. We investigated the effect of postexercise cooling on the incorporation of dietary protein-derived amino acids into muscle protein and acute postprandial (hourly) as well as prolonged (daily) myofibrillar protein synthesis rates during recovery from resistance-type exercise over 2 weeks. Cold-water immersion during recovery from resistance-type exercise lowers the capacity of the muscle to take up and/or direct dietary protein-derived amino acids towards de novo myofibrillar protein accretion. In addition, cold-water immersion during recovery from resistance-type exercise lowers myofibrillar protein synthesis rates during prolonged resistance-type exercise training. Individuals aiming to improve skeletal muscle conditioning should reconsider applying cooling as a part of their postexercise recovery strategy.nnABSTRACT: We measured the impact of postexercise cooling on acute postprandial (hourly) as well as prolonged (daily) myofibrillar protein synthesis rates during adaptation to resistance-type exercise over 2 weeks. Twelve healthy males (aged 21 ± 2 years) performed a single resistance-type exercise session followed by water immersion of both legs for 20 min. One leg was immersed in cold water (8°C: CWI), whereas the other leg was immersed in thermoneutral water (30°C: CON). After water immersion, a beverage was ingested containing 20 g of intrinsically (l-[1- C]-phenylalanine and l-[1- C]-leucine) labelled milk protein with 45 g of carbohydrates. In addition, primed continuous l-[ring- H ]-phenylalanine and l-[1- C]-leucine infusions were applied, with frequent collection of blood and muscle samples to assess myofibrillar protein synthesis rates in vivo over a 5 h recovery period. In addition, deuterated water ( H O) was applied with the collection of saliva, blood and muscle biopsies over 2 weeks to assess the effects of postexercise cooling with protein intake on myofibrillar protein synthesis rates during more prolonged resistance-type exercise training (thereby reflecting short-term training adaptation). Incorporation of dietary protein-derived l-[1- C]-phenylalanine into myofibrillar protein was significantly lower in CWI compared to CON (0.016 ± 0.006 vs. 0.021 ± 0.007 MPE; P = 0.016). Postexercise myofibrillar protein synthesis rates were lower in CWI compared to CON based upon l-[1- C]-leucine (0.058 ± 0.011 vs. 0.072 ± 0.017% h , respectively; P = 0.024) and l-[ring- H ]-phenylalanine (0.042 ± 0.009 vs. 0.053 ± 0.013% h , respectively; P = 0.025). Daily myofibrillar protein synthesis rates assessed over 2 weeks were significantly lower in CWI compared to CON (1.48 ± 0.17 vs. 1.67 ± 0.36% day , respectively; P = 0.042). Cold-water immersion during recovery from resistance-type exercise reduces myofibrillar protein synthesis rates and, as such, probably impairs muscle conditioning.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid31743039,

title = {Short-term muscle disuse induces a rapid and sustained decline in daily myofibrillar protein synthesis rates},

author = {Sean P Kilroe and Jonathan Fulford and Andrew M Holwerda and Sarah R Jackman and Benjamin P Lee and Annemie P Gijsen and Luc J C van Loon and Benjamin T Wall},

doi = {10.1152/ajpendo.00360.2019},

issn = {1522-1555},

year  = {2020},

date = {2020-02-01},

journal = {Am J Physiol Endocrinol Metab},

volume = {318},

number = {2},

pages = {E117--E130},

abstract = {Short-term muscle disuse has been reported to lower both postabsorptive and postprandial myofibrillar protein synthesis rates. This study assessed the impact of disuse on daily myofibrillar protein synthesis rates following short-term (2 and 7 days) muscle disuse under free living conditions. Thirteen healthy young men (age: 20 ± 1 yr; BMI: 23 ± 1 kg/m) underwent 7 days of unilateral leg immobilization via a knee brace, with the nonimmobilized leg acting as a control. Four days before immobilization participants ingested 400 mL of 70% deuterated water, with 50-mL doses consumed daily thereafter. Upper leg bilateral MRI scans and muscle biopsies were collected before and after 2 and 7 days of immobilization to determine quadriceps volume and daily myofibrillar protein synthesis rates. Immobilization reduced quadriceps volume in the immobilized leg by 1.7 ± 0.3 and 6.7 ± 0.6% after 2 and 7 days, respectively, with no changes in the control leg. Over the 1-wk immobilization period, myofibrillar protein synthesis rates were 36 ± 4% lower in the immobilized (0.81 ± 0.04%/day) compared with the control (1.26 ± 0.04%/day) leg ( < 0.001). Myofibrillar protein synthesis rates in the control leg did not change over time ( = 0.775), but in the immobilized leg they were numerically lower during the 0- to 2-day period (16 ± 6%, 1.11 ± 0.09%/day,  = 0.153) and were significantly lower during the 2- to 7-day period (44 ± 5%, 0.70 ± 0.06%/day,  < 0.001) when compared with the control leg. We conclude that 1 wk of muscle disuse induces a rapid and sustained decline in daily myofibrillar protein synthesis rates in healthy young men.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Brunetta2019,

title = {Mitochondrial ROS and Aging: Understanding Exercise as a Preventive Tool},

author = {Henver S. Brunetta and Andrew M. Holwerda and Luc J. C. van Loon and Graham P. Holloway},

doi = {10.1007/s42978-019-00037-1},

issn = {2662-1371},

year  = {2020},

date = {2020-02-00},

journal = {J. of SCI. IN SPORT AND EXERCISE},

volume = {2},

number = {1},

pages = {15--24},

publisher = {Springer Science and Business Media LLC},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid31945740,

title = {PRESENT 2020: Text Expanding on the Checklist for Proper Reporting of Evidence in Sport and Exercise Nutrition Trials},

author = {James A Betts and Javier T Gonzalez and Louise M Burke and Graeme L Close and Ina Garthe and Lewis J James and Asker E Jeukendrup and James P Morton and David C Nieman and Peter Peeling and Stuart M Phillips and Trent Stellingwerff and Luc J C van Loon and Clyde Williams and Kathleen Woolf and Ron Maughan and Greg Atkinson},

doi = {10.1123/ijsnem.2019-0326},

issn = {1543-2742},

year  = {2020},

date = {2020-01-01},

journal = {Int J Sport Nutr Exerc Metab},

volume = {30},

number = {1},

pages = {2--13},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid31721213,

title = {Short-term bed rest-induced insulin resistance cannot be explained by increased mitochondrial H O emission},

author = {Marlou L Dirks and Paula M Miotto and Gijs H Goossens and Joan M Senden and Heather L Petrick and Janneau van Kranenburg and Luc J C van Loon and Graham P Holloway},

doi = {10.1113/JP278920},

issn = {1469-7793},

year  = {2020},

date = {2020-01-01},

journal = {J Physiol},

volume = {598},

number = {1},

pages = {123--137},

abstract = {We determined if bed rest increased mitochondrially derived reactive oxygen species and cellular redox stress, contributing to the induction of insulin resistance. Bed rest decreased maximal and submaximal ADP-stimulated mitochondrial respiration. Bed rest did not alter mitochondrial H O emission in the presence of ADP concentrations indicative of resting muscle, the ratio of H O emission to mitochondrial O consumption or markers of oxidative stress The present data suggest strongly that mitochondrial H O does not contribute to bed rest-induced insulin resistance ABSTRACT: Mitochondrial H O has been causally linked to diet-induced insulin resistance, although it remains unclear if muscle disuse similarly increases mitochondrial H O . Therefore, we investigated the potential that an increase in skeletal muscle mitochondrial H O emission, potentially as a result of decreased ADP sensitivity, contributes to cellular redox stress and the induction of insulin resistance during short-term bed rest in 20 healthy males. Bed rest led to a decline in glucose infusion rate during a hyperinsulinaemic-euglycaemic clamp (-42 ± 2%; P < 0.001), and in permeabilized skeletal muscle fibres it decreased OXPHOS protein content (-16 ± 8%) and mitochondrial respiration across a range of ADP concentrations (-13 ± 5%). While bed rest tended to increase maximal mitochondrial H O emission rates (P = 0.053), H O emission in the presence of ADP concentrations indicative of resting muscle, the ratio of H O emission to mitochondrial O consumption, and markers of oxidative stress were not altered following bed rest. Altogether, while bed rest impairs mitochondrial ADP-stimulated respiration, an increase in mitochondrial H O emission does not contribute to the induction of insulin resistance following short-term bed rest.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid31817402,

title = {Dietary Protein and Physical Activity Interventions to Support Muscle Maintenance in End-Stage Renal Disease Patients on Hemodialysis},

author = {Floris K Hendriks and Joey S J Smeets and Frank M van der Sande and Jeroen P Kooman and Luc J C van Loon},

doi = {10.3390/nu11122972},

issn = {2072-6643},

year  = {2019},

date = {2019-12-01},

journal = {Nutrients},

volume = {11},

number = {12},

abstract = {End-stage renal disease patients have insufficient renal clearance capacity left to adequately excrete metabolic waste products. Hemodialysis (HD) is often employed to partially replace renal clearance in these patients. However, skeletal muscle mass and strength start to decline at an accelerated rate after initiation of chronic HD therapy. An essential anabolic stimulus to allow muscle maintenance is dietary protein ingestion. Chronic HD patients generally fail to achieve recommended protein intake levels, in particular on dialysis days. Besides a low protein intake on dialysis days, the protein equivalent of a meal is extracted from the circulation during HD. Apart from protein ingestion, physical activity is essential to allow muscle maintenance. Unfortunately, most chronic HD patients have a sedentary lifestyle. Yet, physical activity and nutritional interventions to support muscle maintenance are generally not implemented in routine patient care. To support muscle maintenance in chronic HD patients, quantity and timing of protein intake should be optimized, in particular throughout dialysis days. Furthermore, implementing physical activity either during or between HD sessions may improve the muscle protein synthetic response to protein ingestion. A well-orchestrated combination of physical activity and nutritional interventions will be instrumental to preserve muscle mass in chronic HD patients.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid31725358,

title = {Time-dependent regulation of postprandial muscle protein synthesis rates after milk protein ingestion in young men},

author = {Stephan van Vliet and Joseph W Beals and Andrew M Holwerda and Russell S Emmons and Joy P Goessens and Scott A Paluska and Michael De Lisio and Luc J C van Loon and Nicholas A Burd},

doi = {10.1152/japplphysiol.00608.2019},

issn = {1522-1601},

year  = {2019},

date = {2019-12-01},

journal = {J Appl Physiol (1985)},

volume = {127},

number = {6},

pages = {1792--1801},

abstract = {The anabolic action of "fast" whey protein on the regulation of postprandial muscle protein synthesis has been established to be short-lived in healthy young adults. We assessed the time course of anabolic signaling activation and stimulation of myofibrillar protein synthesis rates (MPS) after ingestion of a food source that represents a more typical meal-induced pattern of aminoacidemia. Seven young men (age: 22 ± 1 y) underwent repeated blood and biopsy sampling during primed, continuous l-[-H]phenylalanine and l-[1-C]leucine tracer infusions and ingested 38 g of l-[1-C]phenylalanine- and l-[1-C]leucine-labeled milk protein concentrate. A total of ∼27 ± 4 (∼10 g) and ∼31 ± 1% (∼12 g) of dietary protein-derived amino acids were released in circulation between 0 and 120 min and 120-300 min, respectively, of the postprandial period. l-[-H]phenylalanine-based MPS increased above basal (0.025 ± 0.008%/h) by ∼75% (0.043 ± 0.009%/h;  = 0.05) between 0 and 120 min and by ∼86% (0.046 ± 0.004%/h;  = 0.02) between 120 and 300 min, respectively. l-[1-C]leucine-based MPS increased above basal (0.027 ± 0.002%/h) by ∼72% (0.051 ± 0.016%/h;  = 0.10) between 0 and 120 min and by ∼62% (0.047 ± 0.004%/h;  = 0.001) between 120 and 300 min, respectively. Myofibrillar protein-bound l-[1-C]phenylalanine increased over time ( < 0.001) and equaled 0.004 ± 0.001, 0.008 ± 0.002, 0.017 ± 0.004, and 0.020 ± 0.003 mole percent excess at 60, 120, 180, and 300 min, respectively, of the postprandial period. Milk protein ingestion increased mTORC1 phosphorylation at 120, 180, and 300 min of the postprandial period (all  < 0.05). Our results show that ingestion of 38 g of milk protein results in sustained increases in MPS throughout a 5-h postprandial period in healthy young men. The stimulation of muscle protein synthesis after whey protein ingestion is short-lived due to its transient systemic appearance of amino acids. Our study characterized the muscle anabolic response to a protein source that results in a more gradual release of amino acids into circulation. Our work demonstrates that a sustained increase in postprandial plasma amino acid availability after milk protein ingestion results in a prolonged stimulation of muscle protein synthesis rates in healthy young men.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid31495926,

title = {Skeletal muscle unloading results in increased mitophagy and decreased mitochondrial biogenesis regulation},

author = {Pieter A Leermakers and Anita E M Kneppers and Annemie M W J Schols and Marco C J M Kelders and Chiel C de Theije and Lex B Verdijk and Luc J C van Loon and Ramon C J Langen and Harry R Gosker},

doi = {10.1002/mus.26702},

issn = {1097-4598},

year  = {2019},

date = {2019-12-01},

journal = {Muscle Nerve},

volume = {60},

number = {6},

pages = {769--778},

abstract = {INTRODUCTION: Physical inactivity significantly contributes to loss of muscle mass and performance in bed-bound patients. Loss of skeletal muscle mitochondrial content has been well-established in muscle unloading models, but the underlying molecular mechanism remains unclear. We hypothesized that apparent unloading-induced loss of muscle mitochondrial content is preceded by increased mitophagy- and decreased mitochondrial biogenesis-signaling during the early stages of unloading.nnMETHODS: We analyzed a comprehensive set of molecular markers involved in mitochondrial-autophagy, -biogenesis, -dynamics, and -content, in the gastrocnemius muscle of C57BL/6J mice subjected to 0- and 3-days hind limb suspension, and in biopsies from human vastus lateralis muscle obtained before and after 7 days of one-leg immobilization.nnRESULTS: In both mice and men, short-term skeletal muscle unloading results in molecular marker patterns indicative of increased receptor-mediated mitophagy and decreased mitochondrial biogenesis regulation, before apparent loss of mitochondrial content.nnDISCUSSION: These results emphasize the early-onset of skeletal muscle disuse-induced mitochondrial remodeling.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid30773995,

title = {Energy expenditure and dietary intake in professional football players in the Dutch Premier League: Implications for nutritional counselling},

author = {Naomi Y J Brinkmans and Nick Iedema and Guy Plasqui and Loek Wouters and Wim H M Saris and Luc J C van Loon and Jan-Willem van Dijk},

doi = {10.1080/02640414.2019.1576256},

issn = {1466-447X},

year  = {2019},

date = {2019-12-01},

journal = {J Sports Sci},

volume = {37},

number = {24},

pages = {2759--2767},

abstract = {Selecting effective dietary strategies for professional football players requires comprehensive information on their energy expenditure (EE) and dietary intake. This observational study aimed to assess EE and dietary intake over a 14-day period in a representative group (n = 41) of professional football players playing in the Dutch Premier League (Eredivisie). Daily EE, as assessed by doubly labelled water, was 13.8 ± 1.5 MJ/day, representing a physical activity level (PAL) of 1.75 ± 0.13. Weighted mean energy intake (EI), as assessed by three face-to-face 24-h recalls, was 11.1 ± 2.9 MJ/day, indicating 18 ± 15% underreporting of EI. Daily EI was higher on match days (13.1 ± 4.1 MJ) compared with training (11.1 ± 3.4 MJ; P < 0.01) and rest days (10.5 ± 3.1 MJ; P < 0.001). Daily carbohydrate intake was significantly higher during match days (5.1 ± 1.7 g/kg body mass (BM)) compared with training (3.9 ± 1.5 g/kg BM; P < 0.001) and rest days (3.7 ± 1.4 g/kg BM; P < 0.001). Weighted mean protein intake was 1.7 ± 0.5 g/kg BM. Daytime distribution of protein intake was skewed, with lowest intakes at breakfast and highest at dinner. In conclusion, daily EE and PAL of professional football players are modest. Daily carbohydrate intake should be increased to maximize performance and recovery. Daily protein intake seems more than adequate, but could be distributed more evenly throughout the day.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid31525168,

title = {Protein Supplementation Does Not Augment Adaptations to Endurance Exercise Training},

author = {Kristin L Jonvik and Kevin J M Paulussen and Shiannah L Danen and Ingrid J M Ceelen and Astrid M Horstman and Floris C Wardenaar and Luc J C VAN Loon and Jan-Willem VAN Dijk},

doi = {10.1249/MSS.0000000000002028},

issn = {1530-0315},

year  = {2019},

date = {2019-10-01},

journal = {Med Sci Sports Exerc},

volume = {51},

number = {10},

pages = {2041--2049},

abstract = {INTRODUCTION: Recently, it has been speculated that protein supplementation may further augment the adaptations to chronic endurance exercise training. We assessed the effect of protein supplementation during chronic endurance exercise training on whole-body oxidative capacity (V˙O2max) and endurance exercise performance.nnMETHODS: In this double-blind, randomized, parallel placebo-controlled trial, 60 recreationally active males (age, 27 ± 6 yr; body mass index, 23.8 ± 2.6 kg·m; V˙O2max, 47 ± 6 mL·min·kg) were subjected to 12 wk of triweekly endurance exercise training. After each session and each night before sleep, participants ingested either a protein supplement (PRO; 28.7 g casein protein) or an isoenergetic carbohydrate placebo (PLA). Before and after the 12 wk of training, V˙O2max and endurance exercise performance (~10-km time trial) were assessed on a cycle ergometer. Muscular endurance (total workload achieved during 30 reciprocal isokinetic contractions) was assessed by isokinetic dynamometry and body composition by dual-energy x-ray absorptiometry. Mixed-model ANOVA was applied to assess whether training adaptations differed between groups.nnRESULTS: Endurance exercise training induced an 11% ± 6% increase in V˙O2max (time effect, P < 0.0001), with no differences between groups (PRO, 48 ± 6 to 53 ± 7 mL·min·kg; PLA, 46 ± 5 to 51 ± 6 mL·min·kg; time-treatment interaction, P = 0.50). Time to complete the time trial was reduced by 14% ± 7% (time effect, P < 0.0001), with no differences between groups (time-treatment interaction, P = 0.15). Muscular endurance increased by 6% ± 7% (time effect, P < 0.0001), with no differences between groups (time-treatment interaction, P = 0.84). Leg lean mass showed an increase after training (P < 0.0001), which tended to be greater in PRO compared with PLA (0.5 ± 0.7 vs 0.2 ± 0.6 kg, respectively; time-treatment interaction, P = 0.073).nnCONCLUSION: Protein supplementation after exercise and before sleep does not further augment the gains in whole-body oxidative capacity and endurance exercise performance after chronic endurance exercise training in recreationally active, healthy young males.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid31250889,

title = {Branched-chain amino acid and branched-chain ketoacid ingestion increases muscle protein synthesis rates in vivo in older adults: a double-blind, randomized trial},

author = {Cas J Fuchs and Wesley J H Hermans and Andrew M Holwerda and Joey S J Smeets and Joan M Senden and Janneau van Kranenburg and Annemie P Gijsen and Will K H W Wodzig and Henk Schierbeek and Lex B Verdijk and Luc J C van Loon},

doi = {10.1093/ajcn/nqz120},

issn = {1938-3207},

year  = {2019},

date = {2019-10-01},

journal = {Am J Clin Nutr},

volume = {110},

number = {4},

pages = {862--872},

abstract = {BACKGROUND: Protein ingestion increases muscle protein synthesis rates. However, limited data are currently available on the effects of branched-chain amino acid (BCAA) and branched-chain ketoacid (BCKA) ingestion on postprandial muscle protein synthesis rates.nnOBJECTIVE: The aim of this study was to compare the impact of ingesting 6 g BCAA, 6 g BCKA, and 30 g milk protein (MILK) on the postprandial rise in circulating amino acid concentrations and subsequent myofibrillar protein synthesis rates in older males.nnMETHODS: In a parallel design, 45 older males (age: 71 ± 1 y; BMI: 25.4 ± 0.8 kg/m2) were randomly assigned to ingest a drink containing 6 g BCAA, 6 g BCKA, or 30 g MILK. Basal and postprandial myofibrillar protein synthesis rates were assessed by primed continuous l-[ring-13C6]phenylalanine infusions with the collection of blood samples and muscle biopsies.nnRESULTS: Plasma BCAA concentrations increased following test drink ingestion in all groups, with greater increases in the BCAA and MILK groups compared with the BCKA group (P < 0.05). Plasma BCKA concentrations increased following test drink ingestion in all groups, with greater increases in the BCKA group compared with the BCAA and MILK groups (P < 0.05). Ingestion of MILK, BCAA, and BCKA significantly increased early myofibrillar protein synthesis rates (0-2 h) above basal rates (from 0.020 ± 0.002%/h to 0.042 ± 0.004%/h, 0.022 ± 0.002%/h to 0.044 ± 0.004%/h, and 0.023 ± 0.003%/h to 0.044 ± 0.004%/h, respectively; P < 0.001), with no differences between groups (P > 0.05). Myofibrillar protein synthesis rates during the late postprandial phase (2-5 h) remained elevated in the MILK group (0.039 ± 0.004%/h; P < 0.001), but returned to baseline values following BCAA and BCKA ingestion (0.024 ± 0.005%/h and 0.024 ± 0.005%/h, respectively; P > 0.05).nnCONCLUSIONS: Ingestion of 6 g BCAA, 6 g BCKA, and 30 g MILK increases myofibrillar protein synthesis rates during the early postprandial phase (0-2 h) in vivo in healthy older males. The postprandial increase following the ingestion of 6 g BCAA and BCKA is short-lived, with higher myofibrillar protein synthesis rates only being maintained following the ingestion of an equivalent amount of intact milk protein. This trial was registered at Nederlands Trial Register (www.trialregister.nl) as NTR6047.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid31083048,

title = {One Week of Step Reduction Lowers Myofibrillar Protein Synthesis Rates in Young Men},

author = {Brandon J Shad and Janice L Thompson and Andrew M Holwerda and Ben Stocks and Yasir S Elhassan and Andrew Philp and Luc J C VAN Loon and Gareth A Wallis},

doi = {10.1249/MSS.0000000000002034},

issn = {1530-0315},

year  = {2019},

date = {2019-10-01},

journal = {Med Sci Sports Exerc},

volume = {51},

number = {10},

pages = {2125--2134},

abstract = {PURPOSE: Across the lifespan, physical activity levels decrease and time spent sedentary typically increases. However, little is known about the impact that these behavioral changes have on skeletal muscle mass regulation. The primary aim of this study was to use a step reduction model to determine the impact of reduced physical activity and increased sedentary time on daily myofibrillar protein synthesis rates in healthy young men.nnMETHODS: Eleven men (22 ± 2 yr) completed 7 d of habitual physical activity (HPA) followed by 7 d of step reduction (SR). Myofibrillar protein synthesis rates were determined during HPA and SR using the deuterated water (H2O) method combined with the collection of skeletal muscle biopsies and daily saliva samples. Gene expression of selected proteins related to muscle mass regulation and oxidative metabolism were determined via real time reverse transcription-quantitative polymerase chain reaction (RT-qPCR).nnRESULTS: Daily step count was reduced by approximately 91% during SR (from 13,054 ± 2763 steps per day to 1192 ± 330 steps per day; P < 0.001) and this led to an increased contribution of sedentary time to daily activity (73% ± 6% to 90% ± 3%; P < 0.001). Daily myofibrillar protein synthesis decreased by approximately 27% from 1.39 ± 0.32%·d during HPA to 1.01 ± 0.38%·d during SR (P < 0.05). Muscle atrophy F-box and myostatin mRNA expression were upregulated, whereas mechanistic target of rapamycin, p53, and PDK4 mRNA expression were downregulated after SR (P < 0.05).nnCONCLUSIONS: One week of reduced physical activity and increased sedentary time substantially lowers daily myofibrillar protein synthesis rates in healthy young men.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid31240819,

title = {Lipotoxicity plays a key role in the development of both insulin resistance and muscle atrophy in patients with type 2 diabetes},

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

doi = {10.1111/obr.12862},

issn = {1467-789X},

year  = {2019},

date = {2019-09-01},

journal = {Obes Rev},

volume = {20},

number = {9},

pages = {1205--1217},

abstract = {Insulin resistance and muscle mass loss often coincide in individuals with type 2 diabetes. Most patients with type 2 diabetes are overweight, and it is well established that obesity and derangements in lipid metabolism play an important role in the development of insulin resistance in these individuals. Specifically, increased adipose tissue mass and dysfunctional adipose tissue lead to systemic lipid overflow and to low-grade inflammation via altered secretion of adipokines and cytokines. Furthermore, an increased flux of fatty acids from the adipose tissue may contribute to increased fat storage in the liver and in skeletal muscle, resulting in an altered secretion of hepatokines, mitochondrial dysfunction, and impaired insulin signalling in skeletal muscle. Recent studies suggest that obesity and lipid derangements in adipose tissue can also lead to the development of muscle atrophy, which would make insulin resistance and muscle atrophy two sides of the same coin. Unfortunately, the exact relationship between lipid accumulation, type 2 diabetes, and muscle atrophy remains largely unexplored. The aim of this review is to discuss the relationship between type 2 diabetes and muscle loss and to discuss some of the joint pathways through which lipid accumulation in organs may affect peripheral insulin sensitivity and muscle mass.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid31174213,

title = {Basal and Postprandial Myofibrillar Protein Synthesis Rates Do Not Differ between Lean and Obese Middle-Aged Men},

author = {Imre W K Kouw and Jan Willem van Dijk and Astrid M H Horstman and Irene Fleur Kramer and Joy P B Goessens and François M H van Dielen and Lex B Verdijk and Luc J C van Loon},

doi = {10.1093/jn/nxz104},

issn = {1541-6100},

year  = {2019},

date = {2019-09-01},

journal = {J Nutr},

volume = {149},

number = {9},

pages = {1533--1542},

abstract = {BACKGROUND: Excess lipid availability has been associated with the development of anabolic resistance. As such, obesity may be accompanied by impairments in muscle protein metabolism.nnOBJECTIVE: We hypothesized that basal and postprandial muscle protein synthesis rates are lower in obese than in lean men.nnMETHODS: Twelve obese men [mean ± SEM age: 48 ± 2 y; BMI (in kg/m2): 37.0 ± 1.5; body fat: 32 ± 2%] and 12 age-matched lean controls (age: 43 ± 3 y; BMI: 23.4 ± 0.4; body fat: 21 ± 1%) received primed continuous L-[ring-2H5]-phenylalanine and L-[ring-3,5-2H2]-tyrosine infusions and ingested 25 g intrinsically L-[1-13C]-phenylalanine labeled whey protein. Repeated blood and muscle samples were obtained to assess protein digestion and amino acid absorption kinetics, and basal and postprandial myofibrillar protein synthesis rates.nnRESULTS: Exogenous phenylalanine appearance rates increased after protein ingestion in both groups (P < 0.001), with a total of 53 ± 1% and 53 ± 2% of dietary protein-derived phenylalanine appearing in the circulation over the 5-h postprandial period in lean and obese men, respectively (P = 0.82). After protein ingestion, whole-body protein synthesis and oxidation rates increased to a greater extent in lean men than in the obese (P-interaction < 0.05), resulting in a higher whole-body protein net balance in the lean than in the obese (7.1 ± 0.2 and 4.6 ± 0.4 µmol phenylalanine · h-1 · kg-1, respectively; P-interaction < 0.001). Myofibrillar protein synthesis rates increased from 0.030 ± 0.002 and 0.028 ± 0.003%/h in the postabsorptive period to 0.034 ± 0.002 and 0.035 ± 0.003%.h-1 in the 5-h postprandial period (P = 0.03) in lean and obese men, respectively, with no differences between groups (P-interaction = 0.58).nnCONCLUSIONS: Basal, postabsorptive myofibrillar protein synthesis rates do not differ between lean and obese middle-aged men. Postprandial protein handling, including protein digestion and amino acid absorption, and the postprandial muscle protein synthetic response after the ingestion of 25 g whey protein are not impaired in obese men. This trial was registered at www.trialregister.nl as NTR4060.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}