Dept of Human Services, University of Virginia, Charlottesville, VA, USA.
J Sport Rehabil. 2012 Aug;21(3):209-17. doi: 10.1123/jsr.21.3.209. Epub 2011 Dec 30.
Central and peripheral muscle fatigue during exercise may exacerbate neuromuscular factors that increase risk for noncontact anterior cruciate ligament injury.
To compare lower extremity motor-evoked potentials (MEPs), muscle strength, and electromyography (EMG) activation after an exercise protocol.
Pretest, posttest group comparison.
University laboratory.
34 healthy volunteers (17 female, age = 21.9 ± 2.3 years, weight = 77.8 ± 3.0 kg, height = 171.1 ± 6.6 cm, and 17 male, age = 23.4 ± 6.5 years, weight = 81.6 ± 3.3 kg, height = 179.6 ± 7.3 cm).
A standardized 30-min exercise protocol that involved 5 repeated cycles of uphill walking, body-weight squatting, and step-ups.
Quadriceps and hamstring MEP amplitude (mV) and transmission velocity normalized to subject height (m/s) were elicited via transcranial magnetic stimulation and measured via surface EMG. Quadriceps and hamstring peak EMG activation (% MVIC) and peak torque (Nm/kg) were measured during MVICs. Separate ANCOVAs were used to compare groups after exercise while controlling for baseline measurement.
At baseline, males exhibited significantly greater knee-extension torques (males = 2.47 ± 0.68 Nm/kg, females = 1.95 ± 0.53 Nm/kg; P = .036) and significantly higher hamstring MEP amplitudes (males = 223.5 ± 134.0 mV, females = 89.3 ± 77.6 mV; P = .007). Males exhibited greater quadriceps MEP amplitude after exercise than females (males = 127.2 ± 112.7 mV, females = 32.3 ± 34.9 mV; P = .016).
Males experienced greater peripheral neuromuscular changes manifested as more pronounced reductions in quadriceps torque after exercise. Females experienced greater central neuromuscular changes manifested as more pronounced reduction in quadriceps MEP amplitude. Reduced central neural drive of the quadriceps coupled with knee-extension torque preservation after exercise may increase risk of knee injury in females.
运动过程中中枢和外周肌肉疲劳可能会加剧增加非接触性前交叉韧带损伤风险的神经肌肉因素。
比较运动方案前后下肢运动诱发电位（MEP）、肌肉力量和肌电图（EMG）激活情况。
预测试、后测试组比较。
大学实验室。
34 名健康志愿者（17 名女性，年龄=21.9±2.3 岁，体重=77.8±3.0kg，身高=171.1±6.6cm，17 名男性，年龄=23.4±6.5 岁，体重=81.6±3.3kg，身高=179.6±7.3cm）。
标准化的 30 分钟运动方案，包括 5 次重复的上坡行走、体重量深蹲和台阶上升循环。
经颅磁刺激引出股四头肌和腘绳肌 MEP 幅度（mV）和经身高归一化的传导速度（m/s），并通过表面 EMG 测量。在最大等长收缩（MVIC）期间测量股四头肌和腘绳肌的最大 EMG 激活（%MVIC）和最大峰值扭矩（Nm/kg）。使用独立协方差分析（ANCOVA）在控制基线测量的情况下比较运动后的组间差异。
在基线时，男性的膝关节伸展扭矩明显更大（男性=2.47±0.68Nm/kg，女性=1.95±0.53Nm/kg；P=0.036），且腘绳肌 MEP 幅度明显更高（男性=223.5±134.0mV，女性=89.3±77.6mV；P=0.007）。与女性相比，男性运动后股四头肌 MEP 幅度更大（男性=127.2±112.7mV，女性=32.3±34.9mV；P=0.016）。
男性表现出更大的外周神经肌肉变化，表现为运动后膝关节伸展扭矩明显降低。女性表现出更大的中枢神经肌肉变化，表现为股四头肌 MEP 幅度明显降低。运动后股四头肌的中枢神经驱动减少与膝关节伸展扭矩保持不变可能会增加女性膝关节受伤的风险。
