變向對著地反跳的下肢肌電圖影響

Change of direction effects on electromyographic activity in leg muscles during drop jump

緒論：本研究目的在探討著地反跳後有無變向工作介入，對於下蹲減速與蹬伸階段中的下肢肌肉工作情形。方法：研究招募18位大專院校男性學生（年齡20.4±1.3歲，身高175.5±6.7公分，體重70.5±14.1公斤）為自願的實驗參與者，實驗參與者隨機執行無轉體、變向180度、變向360度的著地反跳動作，並以2塊Kistler測力板（9287BA, 1500Hz）、Noraxon EMG系統（Ultium-EMG, 3000 Hz）分別同步收集地面反作用力與肌電訊號。著地反跳的落下高度為60 cm，收集的右側下肢肌肉為臀大肌、臀中肌、股二頭肌、股直肌、股內側肌、腓腸肌、比目魚肌，及Noraxon myoFORCE模組透過測力板收集到的地面反作用力，用以協助跳躍動作的分期。重複量數單因子變異數分析、HSD法事後比較、Bronferroni法事後比較（α= .05），用以檢定不同跳躍工作間在肌電訊號上的差異性。結果：結果顯示，變向180度、變向360度著地反跳在下蹲減速階段中，有臀中肌、臀大肌的肌電訊號顯著高於無變向著地反跳的情況出現（p < .05），其他肌肉並無因為變向工作介入而產生顯著差異。結論：本研究發現臀中肌、臀大肌在著地反跳與變向工作結合的跳躍動作中，於下蹲減速階段扮演了完成變向預備工作的重要角色，未來需更多相關跳躍變向工作的研究驗證。

Introduction: This study aimed to investigate the level of activation of lower-extremity muscles during the braking phase and the propulsive phase of the drop jump (DJ) under different conditions of change of direction (COD). Methods: Eighteen male college students (20.4±1.3 years old; height 175.5±6.7 cm; body mass 70.5±14.1 kg) volunteered to participate in this study. They were asked to perform the DJ with no COD, 180°COD, and 360°COD in random order. Two Kistler force plates (9287BA, 1500 Hz) and seven Noraxon electromyography (EMG) transducers (Ultium-EMG, 3000 Hz) were synchronized to acquire the ground reaction force and muscle activities, respectively. The DJ drop height was set at a constant 60 cm. EMG sensors were attached to muscles, including the gluteus maximus, gluteus medius, biceps femoris, rectus femoris, vastus medialis, gastrocnemius, and soleus muscles, in the right lower limb. The Noraxon myoFORCE module was used to deconstruct the DJ subphases by ground reaction force . Repeated measures one way ANOVA, with the post-hoc Tukey’s HSD and Bonferroni tests, was used to determine the statistical differences in EMG and ground reaction force between jumping tasks with different COD angles (α= .05). Results: The peak EMG amplitude of the gluteus maximus and gluteus medius in the braking phase was significantly greater for the DJ with 180°COD and 360°COD than for the DJ with no COD (p < .05). No significant differences were found between other muscles. Conclusion: The findings of this study suggest that the gluteus maximus and gluteus medius may play an important and prepared role in helping the performer execute the COD task with the DJ in braking phases. Future studies should investigate COD with jumping task.