Faculty of Health Sciences, Canadian Centre for Activity and Aging, School of Kinesiology, The University of Western Ontario, Arthur and Sonia Labatt Health Sciences Building, London, ON, Canada.
Eur J Appl Physiol. 2010 Jun;109(3):405-15. doi: 10.1007/s00421-010-1364-3. Epub 2010 Feb 4.
The fatigue-related reduction in joint range of motion (ROM) during dynamic contraction tasks may be related to muscle length-dependent alterations in torque and contractile kinetics, but this has not been systematically explored previously. Twelve young men performed a repetitive voluntary muscle shortening contraction task of the dorsiflexors at a contraction load of 30% of maximum voluntary isometric contraction (MVC) torque, until total 40 degrees ROM had decreased by 50% at task failure (POST) to 20 degrees ROM. At both a short (5 degrees dorsiflexion) and long muscle length (35 degrees plantar flexion joint angle relative to a 0 degrees neutral ankle joint position), voluntary activation, MVC torque, and evoked tibialis anterior contractile properties of a 52.8 Hz high-frequency isometric tetanus [peak evoked torque, maximum rate of torque development (MRTD), maximum rate of relaxation (MRR)] were evaluated at baseline (PRE), at POST, and up to 10 min of recovery. At POST, we measured similar fatigue-related reductions in torque (voluntary and evoked) and slowing of contractile kinetics (MRTD and MRR) at both the short and long muscle lengths. Thus, the fatigue-related reduction in ROM could not be explained by length-dependent fatigue. Although torque (voluntary and evoked) at both muscle lengths was depressed and remained blunted throughout the recovery period, this was not related to the rapid recovery of ROM at 0.5 min after task failure. The reduction in ROM, however, was strongly related to the reduction in joint angular velocity (R(2) = 0.80) during the fatiguing task, although additional factors cannot yet be overlooked.
在进行动态收缩任务时，与疲劳相关的关节活动范围 (ROM) 减少可能与肌肉长度依赖性的扭矩和收缩动力学变化有关，但这尚未得到系统研究。12 名年轻男性以 30%最大自主等长收缩 (MVC) 扭矩的收缩负荷进行背屈肌重复自愿肌肉缩短收缩任务，直到在任务失败 (POST) 时总 ROM 减少 50%至 20°ROM 为止。在短（5°背屈）和长（相对于踝关节中立位 0°的 35°足底屈曲关节角度）肌肉长度下，在基线 (PRE)、POST 和恢复 10 分钟时，评估自愿激活、MVC 扭矩和 52.8 Hz 高频等长强直收缩的诱发胫骨前肌收缩特性（峰值诱发扭矩、最大扭矩发展率 (MRTD)、最大松弛率 (MRR)）。在 POST，我们在短和长肌肉长度上测量到类似的与疲劳相关的扭矩（自愿和诱发）降低和收缩动力学减慢（MRTD 和 MRR）。因此，ROM 的疲劳相关减少不能用长度依赖性疲劳来解释。尽管在恢复期间，两种肌肉长度的扭矩（自愿和诱发）均下降且仍然迟钝，但这与 POST 后 0.5 分钟时 ROM 的快速恢复无关。然而，ROM 的减少与疲劳任务期间关节角速度的减少密切相关（R(2) = 0.80），尽管不能忽视其他因素。
