Neuromuscular Electrical Stimulation
Neuromuscular Electrical Stimulation (NMES) is a technique that in the past has been mainly used during rehabilitation. Recently, the technique has also been applied in a more acute clinical setting. Because NMES can evoke a contraction of skeletal muscles without the need for a voluntary contraction, the technique may offer great potential during periods of physical inactivity. Especially during periods when active training is not an option, such as during immobilization, NMES may serve as a means to limit the loss of, or even maintain muscle mass. The main focus of our research is therefore to examine whether NMES is capable of alleviating muscle loss in different populations that are (temporarily) physically inactive.
In our lab, NMES is used to stimulate the different parts of the quadriceps femoris muscle. With subjects lying on a bed in a supine position, self-adhesive electrodes are placed on the muscle belly of the vastus lateralis muscle (2 electrodes), and on the rectus femoris and vastus medialis muscle (1 electrode each). The electrodes are connected to a muscle stimulator device, which sends a small electric current through the electrodes. This current evokes a contraction in the muscle, and can result in full extension of the leg. The intensity of the contraction depends on the intensity (in mA) that is selected by the person handling the device. Depending on the situation this can either be done by the subject himself or by the researcher. A typical stimulation protocol lasts for 30-60 min, starting with a warm-up period at low intensity, followed by an actual stimulation period at high intensity, and a cool-down period again at low intensity. During the stimulation period, the muscles are contracted for short periods of time, with rest in between. In this manner, the NMES session mimics the characteristics of resistance type exercise.