背景：在離心運動造成的肌肉損傷恢復後，能夠減緩下一次離心運動造成的肌肉損傷，此現象稱為重複訓練效應 (repeated bout effect)。過去探討不同離心運動速度影響重複訓練效應的研究，皆以相同反覆次數的離心收縮來進行觀察。然而，若以相同離心收縮時間的面向來探討，是否也有相似的重複訓練效應則需要研究進一步釐清。目的：(一) 探討在進行第一回合不同速度的等速離心運動對膝屈群肌群損傷的影響，以及 (二) 在第二回合皆進行快速度的等速離心運動後，檢驗不同離心運動速度產生重複訓練效應的程度。方法： 16名無阻力訓練經驗之男性配對分組至快速 (210°/s) 及慢速 (30°/s) 離心組。第一回合測驗時，參與者依組別進行6組 (快速：35下/組；慢速：5下/組) 相同離心收縮時間之最大等速離心運動；兩週後所有參與者皆進行快速度之最大等速離心運動 (第二回合測驗)。在每一回合測驗前及測驗後72小時內檢測血清肌酸激酶活性 (CK)、最大等長肌力 (MVIC)、關節活動度 (ROM) 及酸痛指數 (SOR)，並以混合設計二因子變異數分析進行統計分析。結果：(一) 兩組的所有檢測指標，在第一回合離心運動後皆與基準值達顯著差異；其中，快速離心組ROM及MVIC在48小時及72小時顯著低於慢速離心組，但兩組間的CK與SOR在所有時間點皆無顯著差異。(二) 第二回合離心運動後與第一回合的快速離心組進行比較，兩組的CK活性與MVIC皆分別顯著低於及高於第一回合快速離心組，只有快速離心組的SOR顯著低於第一回合快速離心組；ROM的下降幅度方面，快速離心組在48、72小時以及慢速離心組在72小時顯著低於第一回合快速離心組。結論：快速離心運動引起的肌肉損傷較慢速離心運動大，然而在相同離心收縮時間下，快速離心運動與慢速離心運動產生的重複訓練效應是相似的。

Background: A phenomenon by which a bout of eccentric exercise reduces muscle damage in a subsequent bout of eccentric exercise is referred to repeated bout effects (RBE). Studies which investigated effects of eccentric contraction velocity on RBE have used the same number of contractions. No study has yet used the same time under tension when performing different velocity of eccentric contraction. Purpose: This study aimed to determine the effects of different eccentric exercise velocities on muscle damage and repeated bout effects of knee flexors. Methods: Sixteen untrained men were assigned to fast group (FV) or slow group (SV). In the first bout, the FV performed 6set (35rep/set) of eccentric exercise at 210°/s, and the SV performed 6set (5rep/set) of eccentric exercise at 30°/s. Two weeks later, all the participants performed 6set (35rep/set) of eccentric exercise at 210°/s. Serum creatine kinase (CK), maximal voluntary isometric contraction (MVIC), range of motion (ROM) and muscle soreness (SOR) were measured before and after exercises. A mixed model two-way ANOVA was used to analyze the data. Results: (1) After the first bout, all muscle damage indicators were significantly different from baseline in both groups. ROM and MVIC were significantly lower in FV than in SV at 48 and 72 hrs. (2) After the second bout, CK were significantly lower and MVIC were significantly higher than first bout of FV in both groups. Only SOR of FV were significantly lower than first bout of FV. ROM were significantly lower than first bout of FV at 48 and 72 hr in FV and at 72 hr in SV. Conclusion: Fast eccentric exercise induced greater muscle damage; however, RBE was similar between fast and slow eccentric exercise when performing eccentric exercise at the same time under tension.

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