Leg-press resistance training during 20 days of 6° head-down-tilt bed rest prevents muscle deconditioning
Leg-press resistance training during 20 days of 6° head-down-tilt bed rest prevents muscle deconditioning
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DOI：
10.1007/s004210050648
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发表时间：
2000-05-01
影响因子：
3
通讯作者：
Fukunaga, T
中科院分区：
文献类型：
--
作者：
Akima, H;Kubo, K;Fukunaga, T
本研究的目的是探讨在20天的6度头低位卧床期间，阻力训练对人体下肢肌肉形态和功能特性的影响。9名男性被随机分配到阻力训练组（BR-Tr，n = 5）或非训练对照组（BR-Cont，n = 4）。在卧床期间，进行等距腿部按压练习：每天重复3次x 30次（重复之间休息30秒），持续20天。从右大腿和腿部肌肉中获取系列轴向磁共振图像，并估计肌肉体积、肌肉长度和纤维长度。膝伸肌的生理横截面积（PCSA）。膝屈肌、踝跖屈肌和踝背屈肌（胫骨前肌）肌肉群被确定为肌肉体积乘以纤维羽状角的余弦除以纤维长度。测量膝关节伸展过程中的最大随意收缩（MVC）。BR-Tr组膝伸肌PCSA无显著变化，而BR-Cont组PCSA下降7.8%。BR-Tr组和BR-Cont组中膝屈肌和跖屈肌的PCSA在卧床休息后显著降低（膝屈肌，分别为10.2%和11.5%;跖屈肌，分别为13.0%和12.8%）。然而，在两组中，卧床休息对胫骨前肌的肌肉体积和PCSA没有影响。BR-Tr组通过阻力训练维持MVC（降低1%）。相反，在BR-对照组中观察到强度下降（-16%），但该结果不具有统计学显著性。这些结果表明，等长伸腿训练可以防止膝伸肌群的失调（即萎缩和力量下降）。
The purpose of this study was to investigate the effects of resistance training on the morphological and functional properties of human lower limb muscles during 20 days of 6 degrees head-down-tilt bed rest. Nine men were randomly assigned to the resistance training group (BR-Tr, n = 5) or the non-training, control group (BR-Cont, n = 4). Isometric leg-press exercises were performed: 3 s x 30 repetitions (30 s rest between repetitions) daily for 20 days during the bed-rest period. Serial axial magnetic resonance images were taken from the right thigh and leg muscles, and muscle volume, muscle length, and fibre length were estimated. The physiological cross-sectional areas (PCSAs) of the knee extensor. knee flexor, ankle plantarflexor, and ankle dorsiflexor (tibialis anterior) muscle groups were determined as muscle volume multiplied by the cosine of the angle of fibre pennation divided by fibre length. Maximum voluntary contraction (MVC) during knee extension was measured. No significant changes were observed in the PCSA of the knee extensor muscles in BR-Tr group, whereas the PCSA in the BR-Cont group decreased by 7.8%. The PCSA of the knee flexor and plantarflexor muscles in the BR-Tr group and BR-Cont group significantly decreased after bed rest (knee flexors, 10.2% and 11.5%; plantarflexors, 13.0% and 12.8%, respectively). However, in both groups bed rest had no effect on the muscle volume and PCSA of the tibialis anterior. MVC was maintained by resistance training in the BR-Tr group (decreased by 1%). In contrast, a decline of strength was observed in the BR-Cont group (-16%), but this result was not statistically significant. These results suggest that isometric leg-press training prevents the deconditioning (i.e. atrophy and decline of strength) of the knee extensor muscle group.