Effects of Flexibility Training on Back Muscle Flexion-Relaxation Phenomenon

• Main Authors: KANG, PEI-YU, 康倍瑜
• Other Authors: CHEN, YI-LANG
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/bm32vw

碩士 === 明志科技大學 === 工業工程與管理系碩士班 === 107 === Although there have been many studies focusing on the back muscle flexion-relaxation phenomenon (FRP), there is relatively little discussion about how the individual flexibility affects the FRR, and the effect of trained flexibility on FRR is still scant. This study therefore recruited 20 male participants (10 high- and low-flexibility, and were defined as controlled and experimental groups, respectively), who were requested to statically flex their trunks at 7 trunk flexion positions (0°, 15°, 30°, 45°, 60°, 75°, and 90°) and their erector spinae (ES), hamstring activations and lumbosacral angles (LSA) were collected. After 6 weeks of training in the low-flexibility group, the aforementioned experiment was repeated for comparison. The results showed that there was no difference in flexibilities between the controlled group (originally high-flexibility group) and the experimental group (originally low-flexibility group), which were trained in flexibility for a period of 6 weeks. The lower ES activations (average 6.8%MVC after forward flexion of 45°) and the smaller LSA (-12.4°) were observed in the less flexible participants before training, by contrast, the ES activations and LSA were significantly increased after training (9.1%MVC and -5.9°), and there was no difference in FRP patterns between the two groups. However, the hamstring activation after training were significantly higher than the other three flexibility groups. The results of this study show that the flexibility training can postpone the time and reduce the degree of occurred FRR. The findings can be served as a reference for alleviating the lower back load caused by the deeply stooping postures. Keywords: flexion-relaxation phenomenon, flexibility, erector spinae, lumbosacral angle