The effect of neuromuscular electrical stimulation on post-prandial protein accretion during the day and prior to sleep

With human aging there is a gradual but progressive decline in skeletal muscle
mass, termed sarcopenia. While the underlying cause of sarcopenia is likely to
be multifaceted, a primary factor is that elderly individuals frequently
experience short periods of muscle disuse following limb immobilization or
bed-rest (due to injury or illness) causing rapid muscle loss. Muscle loss
during a period of disuse is attributed to an impairment of muscle protein
synthesis rates, especially in the post-prandial phase after a meal. Local
neuromuscular electrical stimulation (NMES) has been shown to directly
stimulate fasting muscle protein synthesis rates. After that, it has previously
been applied in our laboratory in two different settings (i.e. during the day
and prior to sleep) in combination with protein intake. From the results of
both studies, it seemed that application of NMES during the day was more
effective in stimulation muscle protein synthesis than when applied prior to
sleep. However, given the relevance of building new muscle protein to
hospitalized, and often malnourished, patients, the effect of protein ingestion
on skeletal muscle protein accretion should be examined. Therefore, in the
current study, we wish to compare the efficacy of both methods in stimulating
post-prandial muscle protein accretion.

The aim of this study is to investigate the effect of a single bout of NMES on
post-prandial muscle protein accretion during the day and prior to sleep in
healthy elderly males.

20 healthy, elderly men will be allocated to 70 minutes of NMES plus 20 g
intrinsically L-[13C]phenylalanine labelled casein ingestion during the day
(arm 1), or 40 g intrinsically L[13C]phenylalanine labelled casein ingestion
prior to sleep (arm 2). Regular blood samples will be collected and muscle
biopsies will be obtained immediately prior to protein ingestion and 240 min
(arm 1) or 480 min (arm 2) after ingestion from both legs to determine de novo
muscle protein accretion from both the stimulated (STIM) and un-stimulated
control (CON) legs.

Consumption of a bolus of intrinsically L[13C]phenylalanine labelled casein
protein and 70 min of one-legged NMES, either during the day or prior to sleep.

The risks involved in participating in this experiment are minimal. Insertion
of the catheters in a vein is comparable to a normal blood draw and the only
risk is a small local hematoma. This is the same for the muscle biopsies. The
incision made for obtaining the muscle biopsy will be done by an experienced
physician, following local anesthetics of the skin and muscle fascia, and will
heal completely. The test beverages contain intrinsically labeled dietary
protein which is safe for human consumption and has been used in previous
studies (MEC 11-3-057, MEC 11-3-088, MEC 12-3-020, MEC 13-3-024 etc). NMES
carries no potential risks other than slight skin irritation from the surface
electrodes. Due to the possible risk of DVT in arm 2 of the study, a series of
small exercises will be done (to keep the calf pump active) 3 times during the
test day.