Research and Education Center, ASPETAR, Qatar Orthopaedic and Sports Medicine Hospital, Doha, Qatar.
Scand J Med Sci Sports. 2011 Jun;21(3):455-64. doi: 10.1111/j.1600-0838.2009.01032.x. Epub 2009 Dec 21.
To examine the time course of alteration in neural process (spinal loop properties) during prolonged tennis playing, 12 competitive players performed a series of neuromuscular tests every 30 min during a 3-h match protocol. Muscle activation (twitch interpolation) and normalized EMG activity were assessed during maximal voluntary contraction (MVC) of plantar flexors. Spinal reflexes and M-waves were evoked at rest (i.e., H(max) and M(max) , respectively) and during MVC (i.e., H(sup) , V-wave, M(sup) , respectively). MVC torque declined significantly (P<0.001) across the match protocol, due to decrease (P<0.001) in muscle activation and in normalized EMG activity. The impairment in MVC was significantly correlated (r=0.77; P<0.05) with the decline in muscle activation. H(max) /M(max) (P<0.001), H(sup) /M(sup) (P<0.01) and V/M(sup) (P<0.05) ratios were depressed with fatigue and decreased by ∼80%, 46% and 61% at the end of exercise, respectively. Simultaneously, peak twitch torque and M-wave amplitude were significantly (P<0.01) altered with exercise, suggesting peripheral alterations. During prolonged tennis playing, the compromised voluntary strength capacity is linked to a reduced neural input to the working muscles. This central activation deficit partly results from a modulation in spinal loop properties.
为了研究在长时间打网球过程中神经过程（脊髓环路特性）的变化时间进程，12 名竞技运动员在 3 小时的比赛方案中每隔 30 分钟进行一系列神经肌肉测试。在跖屈肌最大自主收缩（MVC）期间评估肌肉激活（抽搐插值）和归一化 EMG 活动。在休息时（即 H(max) 和 M(max)，分别）和 MVC 期间（即 H(sup)、V 波、M(sup)，分别）诱发脊髓反射和 M 波。由于肌肉激活和归一化 EMG 活动的减少（P<0.001），MVC 扭矩在整个比赛方案中显著下降（P<0.001）。MVC 的损伤与肌肉激活的下降显著相关（r=0.77；P<0.05）。H(max) / M(max)（P<0.001）、H(sup) / M(sup)（P<0.01）和 V/M(sup)（P<0.05）比值随疲劳而降低，在运动结束时分别降低约 80%、46%和 61%。同时，峰值抽搐扭矩和 M 波幅度随着运动显著改变（P<0.01），提示外周改变。在长时间打网球过程中，受损的自愿力量能力与向工作肌肉的神经输入减少有关。这种中枢激活缺陷部分源于脊髓环路特性的调制。
