Macaluso Andrea, Nimmo Myra A, Foster John E, Cockburn Muriel, McMillan Nigel C, De Vito Giuseppe
Applied Physiology Group, Strathclyde Institute for Biomedical Science, University of Strathclyde, 76 Southbrae Drive, Glasgow G13 1PP, United Kingdom.
Muscle Nerve. 2002 Jun;25(6):858-63. doi: 10.1002/mus.10113.
It is controversial whether specific tension (the ratio between muscle strength and size) declines with aging. Therefore, contractile muscle volume was estimated separately from the intramuscular noncontractile tissue by magnetic resonance imaging, and maximum isometric torque was measured in the knee extensors and flexors of 10 young (22.8 +/- 5.7 years) and 10 older (69.5 +/- 2.4 years) healthy active women. Specific tension was lower in the older women both in the extensors (93.1 +/- 20.1 kN x m(-2) vs. 112.1 +/- 12.3 kN x m(-2); P < 0.05) and in the flexors (100 +/- 31 kN x m(-2) vs. 142.7 +/- 23.9 kN x m(-2); P < 0.01). This was accompanied by an increase in the percentage coactivation of the knee flexors during knee extension. These data suggest that the lower level of muscle torque in the older women can be explained not only by smaller contractile muscle mass but also by increased coactivation of the antagonist muscles during knee extension.
特定张力（肌肉力量与大小的比值）是否会随着衰老而下降存在争议。因此，通过磁共振成像分别估算收缩性肌肉体积与肌肉内非收缩性组织的体积，并测量了10名年轻（22.8±5.7岁）和10名年长（69.5±2.4岁）健康活跃女性的膝关节伸肌和屈肌的最大等长扭矩。年长女性的伸肌（93.1±20.1 kN·m⁻² 对 112.1±12.3 kN·m⁻²；P<0.05）和屈肌（100±31 kN·m⁻² 对 142.7±23.9 kN·m⁻²；P<0.01）的特定张力均较低。这伴随着膝关节伸展过程中膝关节屈肌共激活百分比的增加。这些数据表明，年长女性较低的肌肉扭矩水平不仅可以通过较小的收缩性肌肉质量来解释，还可以通过膝关节伸展过程中拮抗肌共激活的增加来解释。
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