Homma Toshiyuki, Hamaoka Takafumi, Osada Takuya, Murase Norio, Kime Ryotaro, Kurosawa Yuko, Ichimura Shiro, Esaki Kazuki, Nakamura Fumiko, Katsumura Toshihito
Faculty of Sport and Health Science, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-8577, Japan.
Eur J Appl Physiol. 2015 Mar;115(3):555-63. doi: 10.1007/s00421-014-3029-0. Epub 2014 Oct 26.
Muscle unloading causes muscle function deterioration, but the extent to which training frequency or volume can be reduced while preserving muscle function during muscle unloading is unknown. We examined the effects of low-volume muscle endurance and strength training on forearm muscle oxidative capacity, endurance, and strength during a 3-week immobilization.
Twenty-seven, healthy, male volunteers were divided into four groups: immobilization only (IMM); immobilization with endurance and strength training, once-weekly (IMM + EST1) or twice-weekly (IMM + EST2); and control, without immobilization or training (CNT). Endurance training involved dynamic handgrip exercise, at 30% of maximal voluntary contraction (MVC), until exhaustion (~60 s). Strength training involved intermittent isometric handgrip exercise at 70% MVC (40 s). Muscle oxidative capacity was evaluated after exercise using the phosphocreatine recovery time constant using (31)phosphorus magnetic resonance spectroscopy. Endurance performance was evaluated according to the total work during dynamic handgrip exercise at 30% MVC at 1 Hz until exhaustion.
Muscle oxidative capacity and total work deterioration was restricted to the IMM (P < 0.05) group. MVC decreased in the IMM and IMM + EST1 (P < 0.05) groups. However, the MVC amplitude decrease in the IMM + EST1 group was smaller than that in the IMM (P < 0.05) group. MVC remained unchanged in the other groups.
During the 3-week immobilization, twice-weekly low-volume muscle endurance and strength training prevented deterioration in muscle strength, oxidative capacity, and endurance performance. Moreover, once-weekly muscle endurance and strength training prevented the deterioration of muscle oxidative capacity and endurance performance, and attenuated the degree of muscle strength decline.
肌肉失用会导致肌肉功能恶化，但在肌肉失用期间，在保持肌肉功能的同时可减少训练频率或训练量的程度尚不清楚。我们研究了低训练量的肌肉耐力和力量训练对3周固定期前臂肌肉氧化能力、耐力和力量的影响。
27名健康男性志愿者被分为四组：仅固定组（IMM）；每周进行一次耐力和力量训练的固定组（IMM + EST1）或每周进行两次耐力和力量训练的固定组（IMM + EST2）；以及无固定或训练的对照组（CNT）。耐力训练包括以最大自主收缩（MVC）的30%进行动态握力运动，直至力竭（约60秒）。力量训练包括以MVC的70%进行间歇性等长握力运动（40秒）。运动后使用磷磁共振波谱法通过磷酸肌酸恢复时间常数评估肌肉氧化能力。根据在1 Hz频率下以MVC的30%进行动态握力运动直至力竭时的总功评估耐力表现。
肌肉氧化能力和总功的恶化仅限于IMM组（P < 0.05）。IMM组和IMM + EST1组的MVC均下降（P < 0.05）。然而，IMM + EST1组的MVC幅度下降小于IMM组（P < 0.05）。其他组的MVC保持不变。
在3周的固定期内，每周两次的低训练量肌肉耐力和力量训练可防止肌肉力量、氧化能力和耐力表现的恶化。此外，每周一次的肌肉耐力和力量训练可防止肌肉氧化能力和耐力表现的恶化，并减轻肌肉力量下降的程度。
