Low‐volume resistance exercise attenuates the decline in strength and muscle mass associated with immobilization

Abstract

We determined the effectiveness of low-volume resistance exercise (EX) for the attenuation of loss of muscle mass and strength during leg immobilization. Men (N = 5) and women (N = 12, age 24 ± 5 years, body mass index 25.4 ± 3.6 kg/m(2)) were divided into two groups: exercise (EX; n = 12) and control (CON; n = 5). Subjects wore a knee brace on one leg that prevented weight bearing for 14 days. Resistance exercise (EX; 80% of maximal) was performed by the immobilized limb every other day. Immobilization induced a significant reduction (P < 0.05) in muscle fiber and thigh cross-sectional area (CSA), isometric knee extensor, and plantarflexor strength in the CON (P < 0.01) but not in the EX group. There were significant losses in triceps surae CSA in the CON and EX groups (P < 0.05), but the losses were greater in CON subjects (P < 0.01). A minimal volume (140 contractions in 14 days) of resistive exercise is an effective countermeasure against immobilization-induced atrophy of the quadriceps femoris but is only partially effective for the triceps surae.

Daily torpor reduces mass and changes stress and power output of soleus and EDL muscles in the Djungarian hamster, Phodopus sungorus

“…Between torpor bouts, many mammals (including the hamsters used in the present study) arouse and undertake shivering thermogenesis and exercise, periodically elevating cellular and biochemical processes from the low levels seen in the hypometabolic state (Storey et al, 2010). Such arousal bouts could help to reduce the muscle disuse stimulus for both skeletal muscle atrophy and changes in mechanical properties, in keeping with recent findings that low volume exercise can reduce muscle disuse atrophy in humans (Oates et al, 2010). Arousal from torpor bouts in bats coincides with increases in protein synthesis via activation of mammalian target of rapamycin (mTOR), helping to stop or reduce muscle atrophy during hibernation (Lee et al, 2010).…”

“…Prolonged periods of muscle disuse in non-hibernating mammals are known to result in large and rapid reductions in skeletal muscle size and mechanical performance (Musacchia et al, 1988;Clark, 2009). For example, only 14days of limb immobilisation in humans caused a 22% reduction in the force produced during isometric knee extension (Oates et al, 2010). However, studies with hibernating species that undergo cycles of multi-day torpor bouts show comparatively lower rates of change in the size and mechanical properties of skeletal muscle.…”

Effects of Combination Therapy of Heat Stress and Muscle Contraction Exercise Induced by Neuromuscular Electrical Stimulation on Disuse Atrophy in the Rat Gastrocnemius

“…Exercise is one of the most effective therapies for preventing muscle atrophy [1][2][3] . In general, exercising at ≤65% intensity for 1 repetition is not useful for gaining muscular size or strength 4) .…”

Neuromuscular electrical stimulation increases muscle protein synthesis in elderly type 2 diabetic men

“…The loss of skeletal muscle mass observed during a period of bed rest (23,44,62) or lower limb immobilization (16,26,28,30) has been attributed primarily to a reduction in basal and/or postprandial muscle protein synthesis rates. Maintaining some level of physical activity during a period of disuse is required to attenuate the decline in muscle protein synthesis rates and prevent excessive muscle tissue loss (2,12,24,47,52,64). However, under many clinical conditions (e.g., hospitalization due to illness or injury), maintenance of physical activity is often not practical or even feasible.…”