Protective Effect Conferred by Low-Intensity Eccentric Exercise

• Main Authors: Liao, Hwa-dean, 廖華典
• Other Authors: Trevor C. Chen
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/87052227446231685806

碩士 === 國立嘉義大學 === 體育與健康休閒研究所 === 98 === Abstract Background: Dudley, Tesch, & Miller (1991) showed that eccentric exercise (ECC) is the most effective way to enhance muscle strength. Yet because it involves high tension and low motor unit activation, it is more likely than other types of exercise to result in muscle damage. It is known that while maximal eccentric exercise (100%ECC) confers a stronger protective effect than submaximal ECC, it can also cause muscle soreness and discomfort. Thus, developing a low-intensity eccentric exercise (10%) that does not cause muscle damage and can provide the repeated bout effect (RBE) may be the best way to encourage people to engage in ECC. Purpose: This study tested the hypothesis that four bouts of low-intensity ECC would confer protection to reduce the extent of muscle damage from a subsequent bout of maximal eccentric exercise. Methods: Twenty untrained men were placed into eccentric training (ET) or control (CON) groups (n=10 per group) based on pre-exercise maximal isometric strength (MVC) at elbow flexion of 90○. Subjects in the ET group performed 5 x 6 eccentric contractions with a load of 10% MVC (10%ECC) once a week for four weeks, followed 1 week later by 5 x 6 100%ECC of the elbow flexors of the non-dominant arm. The CON group performed only one bout of 5 x 6 100%ECC. Changes in MVC, relaxed elbow joint angle (RANG), upper arm circumference (CIR), muscle soreness (SOR) and plasma creatine kinase (CK) activity were measured before, immediately after, and 2-5 days after each exercise. Data were analyzed with a two-way mixed model or repeated measure analysis of variance (ANOVA). Results: Significant improvement (p <.05) was noted in SOR, CIR and MVC after 4-week 10%ECC compared to baseline for the ET group. There was no significant difference in SOR, CIR or RANG (p >.05) after 100%ECC between the ET and CON groups. However, changes in MVC and CK for the ET group were significantly smaller (p <.05) than for the CON group. Conclusions: These results suggest that repeated low-intensity eccentric exercise training can provide a significant protective effect to reduce the extent of muscle damage from a subsequent bout of maximal eccentric exercise.