אימונים Low-Intensity Exercise Can Increase Muscle Mass and Strength Proportionally to Enhanc

[Mike Bikov]

J Appl Physiol. 2012 May 24. [Epub ahead of print]
Low-Intensity Exercise Can Increase Muscle Mass and Strength Proportionally to Enhanced Metabolic Stress Under Ischemic Conditions.
Takada S, Okita K, Suga T, Omokawa M, Kadoguchi T, Sato T, Takahashi M, Yokota T, Hirabayashi K, Morita N, Horiuchi M, Kinugawa S, Tsutsui H.
Source

1Hokkaido University Graduate School of Medicine.
Abstract

Skeletal muscle bulk and strength are becoming an important therapeutic target in medicine. In order to increase muscle mass, however, intensive, long-term mechanical stress must be applied to the muscles, and such stress is often accompanied by orthopedic and cardiovascular problems. We examined the effects of circulatory occlusion in resistance training combined with a very low-intensity mechanical load on enhancing muscular metabolic stress and thereby increasing muscle bulk. Muscular metabolic stress, as indicated by the increases in inorganic phosphate (Pi) and a decrease in intramuscular pH, was evaluated by (31)P-magnetic resonance spectroscopy during unilateral plantar-flexion at 20% of the one-repetition maximum (1-RM) with circulatory occlusion for 2 min in 14 healthy, male untrained participants (22 yr) at baseline. Participants performed 2 sets of the same exercise with a 30-sec rest between sets, 2 times/day, 3 days/wk, for 4 wks. The muscle cross-sectional area (MCA) of the plantar-flexors and the 1-RM were measured at baseline and after 2 and 4 wks of training. MCA and 1-RM were significantly increased after 2 and 4 wks (P<0.05, respectively). The increase in MCA at 2 wks was significantly (P<0.05) correlated with the changes in Pi (r=0.876) and intramuscular pH (r=0.601). Furthermore, the increases in MCA at 4 wks and 1-RM at 2 wks were also correlated with the metabolic stress. Thus enhanced metabolic stress in exercising muscle is a key mechanism for favorable effects by resistance training. Low-intensity resistance exercise provides successful outcomes when performed with circulatory occlusion, even with a short training period.

facepalm