A Comparison of Hamstring and Quadriceps Muscular Work and Power in Elite Karate Athletes before and after Fatigue

The rate of performed work by most muscles is rarely constant with time. Because of rapid time-course changes, it has been necessary to calculate muscle power as a function of time. The aim of the present study was to assess the differences in Hamstring and Quadriceps muscular work and power in elite karate athletes before and after fatigue in order to identify injury risk factors. Fourteen female elite karate athletes (15.5±1.3 years) were evaluated using isokinetic dynamometer at 60◦/s, 180◦/s and 300◦/s before and after Hamstring and Quadriceps muscular fatigue. No differences were found in Hamstring and Quadriceps muscular power before and after fatigue at the 180◦/s speed (p> 0.05). At 180◦/s speed, the Hamstring presented no differences in muscular work after fatigue muscular test (p<0.05). At the 60 and 300◦/s speeds, Hamstring and Quadriceps muscular power presented a lower power after fatigue test (p=0.04). Based on the present results, fatigue does not have a significant effect on power and the work done by karate athletes' muscles around knee joint at medium speed however, generally, fatigue probably causes imbalance in mechanical power and work done by hamstring and quadriceps at other angular .