Abstract: Objective To analyze the data of concentric (c) and eccentric (e) peak torque of hamstring (H) and quadricep (Q) in different gender and angle after 4-week concentric and eccentric isokinetic exercise training on knee, in order to provide suggestions for the knee extensor and flexor in rehabilitation exercise prescription. Methods 28 healthy college students from May to June 2014 in our college participated in maximum concentric (n=14) or eccentric (n=14) resistance training of the right knee extensors and flexors 3 times per week for 4 weeks. The concentric strength was measured with BIODEX isokinetic dynamometer assessment system 4 at 30 °/s, 60 °/s, 90 °/s, and eccentric strength was measured at 60 °/s, 120 °/s, 180 °/s. PT, H/Q (He/Qc, Hc/Qc) ratio and H/H (He/Hc) or Q/Q(Qe/Qc) ratio were analyzed. Results Concentric isokinetic training could improve the Hc and He at 60 °/s and 90 °/s (P<0.05), and the Qe and Qc increased at 30 °/s, 60 °/s, 90 °/s respectively (P<0.01). There was no significant improvement after eccentric training (P>0.05). After concentric isokinetic training, the He/Qc ratio decreased at 90 °/s (P<0.05), the Hc/Qc ratio decreased at 30 °/s (P<0.05). However, there was no difference in He/Qc and Hc/Qc after eccentric contraction (P>0.05). The Qc/Qe ratio increased at 60 °/s and 90 °/s (P<0.05), and the Hc/He ratio decreased at 90 °/s (P<0.05) after concentric training. There was no difference in Hc/He and Qc/Qe after eccentric contraction (P>0.05). There were significant differences in Hc, He, Qc, Qe and He/Qc ratio between different genders (P<0.05). Conclusion Concentric training and eccentric training have different influences on the muscle strength after 4 weeks training. Eccentric training only can reduce the knee stability. Hc/He ratio and Qc/Qe ratio can be used to evaluate the knee muscle function. Gender should be considered into training.

Key words: concentric isokinetic training, eccentric isokinetic training, peak torque, hamstring/quadricep ratio, knee