Cardiff School of Sport, University of Wales Institute, Cyncoed Road, Cardiff CF23 6XD, Wales, UK.
J Electromyogr Kinesiol. 2010 Oct;20(5):973-9. doi: 10.1016/j.jelekin.2010.03.011. Epub 2010 Apr 20.
The purpose of the study was to investigate whether boys and men utilise different control strategies whilst hopping. Eleven boys (11-12yr old) and ten men completed hopping at 1.5Hz, 3.0Hz and at their preferred frequency. A footswitch measured contact and flight times, from which leg stiffness was calculated. Simultaneously, surface electromyograms (EMGs) of selected lower limb muscles were recorded and quantified for each 30ms period during the first 120ms post-ground contact. At 1.5Hz there were no differences between the groups in relative stiffness or muscle activity. At 3.0Hz men had significantly shorter contact times (P=0.013), longer flight times (P=0.002), greater relative stiffness (P=0.01) and significantly greater soleus (P=0.012) and vastus lateralis (P<0.001) activity during the initial 30ms post-ground contact. At the preferred frequency men hopped significantly faster than the boys (P=0.007), with greater leg stiffness (P<0.01) and with more extensor activity in most time periods. Boys and men demonstrated similar control strategies when hopping at a slow frequency, but when hopping frequency increased men were able to better increase feedforward and reflex muscle activity to hop with greater relative stiffness.
本研究旨在探讨男孩和男性在跳跃时是否采用不同的控制策略。11 名男孩（11-12 岁）和 10 名男性以 1.5Hz、3.0Hz 和他们的偏好频率完成跳跃。脚踏开关测量接触和飞行时间，由此计算出腿部刚度。同时，记录选定的下肢肌肉的表面肌电图（EMG），并在首次接触地面后的 120ms 内的每个 30ms 期间进行量化。在 1.5Hz 时，两组之间的相对刚度或肌肉活动没有差异。在 3.0Hz 时，男性的接触时间明显缩短（P=0.013），飞行时间延长（P=0.002），相对刚度增加（P=0.01），并且在首次接触地面后的最初 30ms 内，比目鱼肌（P=0.012）和股外侧肌（P<0.001）的活动显著增加。在偏好频率下，男性跳跃速度明显快于男孩（P=0.007），腿部刚度更高（P<0.01），并且在大多数时间段内伸肌活动更多。男孩和男性在以较慢的频率跳跃时表现出相似的控制策略，但当跳跃频率增加时，男性能够更好地增加前馈和反射肌肉活动，以更大的相对刚度跳跃。
