1 The large four - part extensor muscle at the front of the thigh.

2 The extensor muscle strength of shoulder joint is more influencing than the flexor muscle strength of shoulder.

3 Results The mean follow-up was 8 months. The extensor muscle strength and electromyography in forearm completely recovered.

4 After 8 weeks of training, knee extensor and flexor muscles strength can be improved, but knee extensor muscle torque increase more than flexor muscle.

5 The elderly are tend to flex hip joint more and use hip extensor muscle to propel the body forward.