比較固定與動態轉動慣量阻力訓練器材在肱二頭肌上的表現

Abstract

執行慣性式阻力訓練時的向心收縮所產生的力量與收縮速度成反向關係，肌肉在向心收縮末期 (60-70%) 發生減速期，使動作無法維持高速率。因此，為了使用更快的速度執行，勢必要用較輕的負荷才能使輪盤產生高速，而所產生的離心收縮負荷較小；反之亦然。目的：本研究希望藉由使用自製的動態轉動慣量阻力訓練器材，使向心收縮期間產生較快的速度且在離心收縮期間能累積更多角動量，造成更多的離心收縮負荷，並能符合肌肉速度力量曲線，讓高速度的動作與高慣量互相搭配而產生更好的離心收縮強度。方法: 本研究招募12位健康男性，使用自製的轉動慣量阻力訓練器材進行3種不同慣量(固定輕轉動慣量、動態轉動慣量、固定重轉動慣量)各5次的向心-離心收縮，共兩組，組間休息2分鐘，並收取肱二頭肌產生衝量與肱二頭肌肌肉活化情形效果進行分析比較。結果：向心初期固定重轉動慣量之衝量與iEMG顯著高於固定輕轉動慣量與動態轉動慣量；向心末期時動態轉動慣量與重轉動慣量之衝量與iEMG顯著高於輕轉動慣量；離心初期時動態轉動慣量之衝量顯著高於固定重轉動慣量；離心末期時動態轉動慣量與固定重轉動慣量之衝量與iEMG顯著高於輕轉動慣量。討論：動態轉動慣量在向心收縮期速度快且在向心末期轉動慣量變大，因此比起其他兩者慣量在轉折時累積較多角動量。結論：動態轉動慣量擁有固定輕轉動慣量的速度快、固定重轉動慣量的角動量大等優點。向心收縮期：轉動慣量小、施於機台速度快。離心收縮期：轉動慣量大、角動量增加，因為離心收縮具有機械性增強的效益，因此對離心收縮的肌肉訓練有所助益。

Purpose: A self-designed dynamic inertia resistance training equipment was used to generate a faster velocity during concentric phase and accumulate more angular momentum during eccentric contraction. This study was designed to compare the effect of different inertial resistance equipment. Method: Twelve healthy men were recruited as subjects, using three different inertial resistances (fixed light moment of inertia, dynamic moment of inertia and fixed heavy moment of inertia) to execute 5 times con-ecc action of two sets, two minutes rest between sets. The biceps muscle impulse and EMG were analyzed. Result: In initial concentric phase, the impulse of heavy MOI and iEMG were significantly higher than light MOI and dynamic MOI; In the end of concentric phase, dynamic MOI and heavy MOI impulse and iEMG were significantly higher than light MOI; In initial eccentric phase, dynamic MOI impulse was significantly higher than heavy MOI; In the end of eccentric phase, dynamic MOI and heavy MOI impulse and iEMG were significantly higher than the light MOI. Discussion: Dynamic MOI had higher velocity and MOI becomes larger at the end of concentric phase, so accumulated more angular momentum than other two momentums. Conclusion: Dynamic inertia resistance has the advantages of both fixed light MOI's fast velocity and fixed heavy MOI's large angular momentum, therefore, the effect of eccentric overload could be increased to enhanced strength training.