|Title:||Ultrasonography of the semitendinosus muscle in male subjects : relationship of cross-sectional area and flexibility before and after warm up exercise|
|Subject:||Muscles -- Examination|
Hong Kong Polytechnic University -- Dissertations
Department of Optometry and Radiography
|Pages:||xi, 114,  leaves : ill. (some col.) ; 30 cm|
|Abstract:||Hamstring injuries are common among athletes, especially for those performing high speed, high load activities. Hamstring muscle strains account for the largest percentage of muscle injuries of any of the muscle groups. Hamstring muscle group consists of biceps femoris, semimembranosus and semitendinosus. It was believed that the more energy that the muscle can absorb, the more resistant the muscle is to injury (William & Garrett, 1996). Semitendinosus is more likely to suffer from injury due to its less muscle activation ability and hence less energy absorption ability. Thus, the present study only investigated the semitendinosus. It has been believed that warm-up exercise can help to increase the flexibility of the muscle and there is a strong association between the cross-sectional area (CSA) of the muscle and its flexibility. There is little information relating the relationship of muscle CSA and its flexibility, as well as how the effect of warm-up exercise associated with flexibility. The present project was aimed to investigate the relationship between structural change and flexibility of semitendinosus, so as to increase understanding the effect of warm up exercise on structural change and flexibility. A total of 34 healthy male volunteers, aged from 18 to 25 years were recruited in the campus of The Hong Kong Polytechnic University to participate in the study. Each volunteer attended two separate sessions to perform two different kinds of warm-up exercises, either stretching or stair-stepping in each session. The body weight and height were recorded when the volunteers attended the fast session. The flexibility and cross-sectional area (CSA) of both semitendinosus before and immediately after warm-up exercise were measured. All volunteers gave written informed consent before the participation in the present study. Paired t-test was used to compare the CSA of semitendinosus and the flexibility before and after two types of warm-up exercises individually, as well as to compare the difference in the changes of CSA of the semitendinosus between the two types of warm-up exercises. Pearson correlation coefficient was used to indicate the correlation between the CSA of the semitendinosus and its flexibility before and after the two types of warm-up exercises. The flexibility of the semitendinosus was significantly increased after stretching and stair-stepping. The CSA of semitendinosus was also significantly increased after stretching and stair-stepping. The increase in CSA of semitendinosus muscles after stair-stepping was greater than that after stretching, although such increase in CSA of the semitendinosus was not significantly different between the two types of warm-up exercises. The change of CSA of semitendinosus muscle and its flexibility was also not significantly correlated after exercises. The results suggested that both stretching and stair-stepping are effective warm-up exercises to enhance flexibility, while stretching yielded a greater flexibility gain than stair-stepping. There is a direct relationship between the CSA of muscle and its ability to generate force. Muscle strength can be increased after stretching and stair-stepping to induce a higher ability to generate force, so as to enhance athletes' performance. Greater increase in CSA of semitendinosus was found after stair-stepping than after stretching, suggesting that stair-stepping as warm-up exercise induces greater strength and higher ability of the muscle to generate force. There was no association between CSA of semitendinosus muscle and its flexibility. Assessment of flexibility was suggested to perform before sports involving musculotendinous junction injuries, such as dancing and running. Ultrasonography of muscle is suggested to assess the muscle CSA and its status before vigorous exercise and intensive training, especially for the sports involving explosive start-stop, such as basketball, volleyball, soccer, squash and ruby.|
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