二種不同型式阻力訓練對肌肉功能及保留效果之影響

Abstract

背景：阻力訓練是常見的運動模式，包括向心阻力訓練 (concentric resistance training, CRT) 和離心阻力訓練 (eccentric resistance training, ERT)，而短週期漸進式阻力訓練計劃可能有助於提高肌肉力量、肌肉肥大和功能，同時也能在復健計劃設計和運動表現改善方面具有重要意義。現代人的生活中常會因為多種原因 (例如：疫情因素) 必須停止身體活動一段時間，但何種阻力訓練型式可以對接受訓練肌肉群產生最佳的效果呢？哪一種阻力訓練之後，其維持肌肉力量、肌肉肥大和功能的效果會最佳呢？目的：1.針對單側股四頭肌群 (quadriceps femoris muscle，QF) 進行6週單純向心阻力訓練或單純離心阻力訓練對提升股四頭肌肉力量、肌肉肥大和功能的效果做比較，以釐清哪種阻力訓練型式產生的訓練效果會最佳；2. 比較6週停止訓練後，何種型式阻力訓練對股四頭肌肉力量、肌肉肥大和功能的維持或保留效果會最佳。方法：召募24名年輕健康男子為研究對象，並以隨機分派的方式分成向心阻力訓練組 (CRT；n = 12) 和離心阻力訓練組 (ERT；n = 12)。CRT及ERT的研究對象在腿伸肌阻力訓練機台上，分別接受CRT和ERT訓練。每位研究對象以每週訓練2天，每天一回合漸增強度，共30次 (50%-100% 1RM) 阻力訓練，接受為期6週的漸增強度阻力訓練。依變項計有：腿圍 (leg circumference, CIR)、位置覺 (position sense, PS)、關節釋放角度 (joint release angle, JRA)、力量覺 (force match, FM)、最大自主等長收縮肌力 (maximum voluntary isometric contraction, MVC)、等速向心肌力 (maximal isokinetic concentric strength) 與等速離心肌力 (maximal voluntary eccentric strength)。所有研究對象在前測、訓練後第4天，以及訓練後第2、4、6週各接受一次依變項測驗。結果：6週CRT及ERT皆能有效提升肌肉力量 (p<.05)，且ERT在離心肌力的提升效果顯著優於CRT。腿圍和本體感覺則兩組間無顯著差異 (p >.05)。肌肉力量的保留效果，ERT顯著優於CRT (p <.05)。結論：本研究結果顯示，6週的CRT和ERT皆顯著提升最大等長肌力、向心肌力和離心肌力，並且ERT對於離心肌力的增加顯著大於CRT，並且在最大等長肌力、向心肌力和離心肌力的維持效果都優於CRT。Background: Resistance training is a common exercise modality, including concentric resistance training (CRT), eccentric resistance training (ERT), and short-term resistance training program may help enhance muscle strength, hypertrophy, and function, while also playing a significant role in rehabilitation program design and athletic performance improvement. Nowadays, it is commonly seen that people stop physical activity due to several reasons (e.g., epidemical factors) and that proposed the issues of the optimal type of resistance training to induce desirable effects on trained muscle, as well as the most effective resistance training program to preserve and maintain muscle function. In modern life, people often cease physical activity for a period due to various reasons (e.g., the impact of a pandemic). However, which type of resistance training produces the most training effects on the trained muscle groups? Furthermore, which type of resistance training is best for maintaining muscle strength, hypertrophy, and function after training program? Purposes: 1. To compare the effects of 6-week concentric-only or eccentric-only resistance training of the quadriceps femoris muscle (QF) on muscle strength, hypertrophy, and function to determine which type of resistance training produces the best training effect; 2. To compare effects of concentric-only and eccentric-only training on maintaining muscle function and performance. Methods: Twenty-four young healthy men were recruited and randomly assigned to the concentric resistance training group (CRT; n = 12) and the eccentric resistance training group (ERT; n = 12). Participants received either CRT or ERT on the same leg extension machine. The training protocol was scheduled for 2 days a week (30 repetitions 50%-100% 1RM) for 6 weeks. The following variables were used to determine muscle function and performance: upper thigh circumference (CIR), position sense (PS), joint reaction angle to release (JRA), force match (FM), maximum voluntary isometric (MVC), maximal isokinetic concentric strength and maximal voluntary eccentric strength of the quadriceps. Each participant will be asked to complete two preliminary and familiarization sessions and muscle function measurements after the program. The follow-up of measurements of maintaining muscle function and performance were measured every 2 weeks and last for 6 weeks after the last training session. Results: Both 6-week CRT and ERT significantly improved muscle strength (p< .05), with ERT showing a significantly greater improvement in eccentric muscle strength compared to CRT. There were no significant differences between the two groups in terms of leg circumference and proprioception (p > .05). The retention effect of muscle strength after training cessation was significantly better in the ERT group compared to the CRT group (p < .05). Conclusion: The results of this study indicate that both 6 weeks of CRT and ERT significantly improved maximum isometric, concentric and eccentric muscle strength. However, ERT led to a significantly greater increase in eccentric muscle strength compared to CRT, and it also demonstrated superior maintenance effects on maximum isometric, concentric, and eccentric muscle strength compared to CRT.