- 學位論文
棒球選手與一般人旋轉肌群在不同運動狀態下肌肉共同收縮的差異
The differences of rotator cuff muscles co-contraction at various exercise condition between the baseball players and normal subjects
摘要
關節中作用肌（agonist）及擷抗肌（antagonist）在動作過程中同時活化收縮，這個作用機制在以往被認為是浪費能量及減少對於關節力矩的輸出。但隨著一些研究的進行，發現肌肉共同收縮不僅能達到動作的準確性，並且可以維持關節的穩定。所以在本研究中藉由量測肩旋轉運動的棒球投手及一般人其肌群相互間的收縮大小，可以了解肌肉在維持關節穩定中所扮演的角色及功能。結果發現，在等速肌力測試儀上，肩關節外展70度且角速度為60度/秒時會有較大的肌力參數；而在肌電活化的共同指標部分，作外旋動作時會隨著角速度的增加而增大，在角度部分則無明顯差異，在作內旋動作時，會在肩關節外展90度且角速度為210度時有較大的共同收縮；而在投球測試中，在球速最快時，棒球選手的加速期前共同收縮會小於加速期後，而控制組剛好相反。在等速肌力測試儀不同運動狀態下，各肌肉的活化都有所不同，因此，可針對投球結果所發現之需加強的肌肉進行訓練。
並列摘要
The simultaneous activation of agonist and antagonist muscles acting on the same joint seems wasteful as their reciprocal action would reduce the resultant muscle torque. However, with some research identified, some specific advantages exist for this strategy. Muscle co-contraction represents a useful strategy especially when a movement is performed requiring a high degree of accuracy. Moreover, muscle co-contraction makes a joint stiffer and more difficult to perturb. Therefore, quantifying the muscle activation during the motion could help better understanding the contribution and function of muscles in joint motion. Moreover, every muscle has different slow/fast twitch fibers compositions. For that reason, muscles around the joint should have different co-contraction condition to keep joint stability in different motion situation. In this proposed project, we are going to discuss the contributions between muscles activations at different joint position and joint movement velocity in shoulder rotation motion. According to the result, the muscle strength was higher when the shoulder joint at 70o abduction and angular velocity at 60o/sec. The EMG data shows that when supination, the co-contraction of supination muscle and pronation muscle was increased accompanied with the increase of angular velocity but not angle. And when pronation, the shoulder abduction at 90o and angular velocity at 120o/sec has more co-contraction. In the pitching test, the co-contraction of baseball player before accelerated phase was less then after when the highest ball velocity. And the control group was contrary. The muscle activity were different in distinct exercise condition. Therefore, according to the pitching results, the training program could set focus on the target muscle.