Different Speed Of Eccentric Strenght Training On Fast Strength Of Lower Body

Sports injury is an important factor which affects athlete from systematic training. Enhancing muscle eccentric ability is positive for preventing sports injury, improving maximum muscle strength, fast strength, and sports performance. However, the studies related to eccentric training is quite limited, neither training methods nor the training load. Besides, the determination of eccentric training plan is still at a extensive stage. This research tends to training knee extension muscles, knee flexion muscles, ankle dorsi flexion muscles and ankle plantar flexion muscles with different eccentric contraction speed. Isokinetic muscle strength test is adapted to compare the strength characteristics of the major muscles of lower body. The purposes of the research are finding the best eccentric contraction speed for improving the fast strength of lower body, and providing theoretical basis and application reference for determining the rehabilitation strength training plan.29 subjects, randomly divided into two groups, did fast strength training of the major muscles of lower body. Firstly, the two groups both concentric contracted quickly to end of the range of join motion, then immediately started eccentric contraction at a quick speed (1s) or a relatively slow speed (5s).7 repetitions per time,5 sets in total. The interval time between each session is 3 minutes. This training lasted for six weeks,3 times per week. There were muscle strength tests of knee extension muscles, knee flexion muscles, ankle dorsi flexion muscles and ankle plantar flexion muscles before and after the training, using BIODEX SYSTEM 3.0 isokinetic muscle strength test system. The indexes which were chosen including kinetic parameters such as these muscles'peak torque during concentric and eccentric contractions and the durations to reach peak torque, and some fast strength ability indexes of the whole lower body such as CMJ jumping and standing long jump. The test results were carried on statistics processing, compared the different effects on fast strength of lower body from different eccentric contraction speed.Results:1. After 6 weeks training, both in S group and F group, the concentric peak torques (60°/s)of major lower body muscles were improving. Compared with S group, in F group, the peak torque of ankle plantar flexion muscles had significant difference(p<.05).2. After 6 weeks training, both in S group and F group, the eccentric peak torques (60°/s)of major lower body muscles were improving. There was no significant difference between the two groups.3. After 6 weeks training, both in S group and F group, the eccentric peak torques(180°/s)of major lower body muscles were improving. There was no significant difference between the two groups.4. After 6 weeks fast eccentric strength training, the times to peak torque of knee extension muscles, ankle dorsi flexion muscles and ankle plantar flexion muscles were shortened. Compared with S group, F group's time to peak torque of ankle plantar flexion muscles had very significant difference (p<.01). 5. After 6 weeks training, the height of CMJ jump of F group was higher than S group, which had statistics difference (p<.05).Conclusion:1.Both the fast and slow eccentric training can improve the maximum concentric strength of muscles of lower body. The effect on improving the maximum contraction strength of ankle dorsi flexion muscles of fast eccentric training is significantly better than slow eccentric training.2. Both the fast and slow eccentric training can improve the maximum eccentric strength of muscles of lower body effectively.3. The fast eccentric training improves the fast eccentric strength of ankle dorsi flexion muscles significantly. The best speed-load for improving the fast eccentric strength of the other muscles of lower body are not quite clear yet.4.6 weeks fast eccentric training can improve CMJ jumping performance better than slow eccentric training significantly.