Effect of Muscular Fatigue on the Sensation of Knee joint Position in Elite Karate Athletes

The kicks are performed by quick knee extension-flexion in karate. Any poor performance of joint proprioception is a risk factor for athletes. Muscular fatigue, as an inevitable factor of any physical activity, can cause problem in proprioception performance. The present study was carried out to investigate the effect of knee muscle fatigue on knee proprioception performance in karate athletes.

The sensations of knee joint position of 14 female elite karate athletes (age: 15±1.3 years, height: 161±7 cm, weight: 54 kg±34 kg) were evaluated using the isokinetic device at 30, 45, and 60 degrees before and after fatigue. Data analysis was carried out using paired t-test with p. value set at 0.05.

The muscle fatigue had a significant effect on reconstruction error of the knee joint in 60 degree angle. Fatigue caused an increase in reconstruction error and decreased knee joint sensation. Also, an increase in joint reconstruction error after fatigue at 30 and 45 degree angles was observed, which was not statistically significant.  

According to the results, it can be concluded that decrease in the ability to control knee joint position due to muscular fatigue in karate athletes, especially at the end of the range, may result in knee injury, in addition to weakness in correct technique implementation. Because the defect in the proprioception of the joints can lead to a defect in the simultaneous recall of the motor units of the quadriceps and hamstrings, and it may increase the risk of damage to the knee anterior cruciate ligament, thus, it can be stated that improving muscle endurance can increase the time to reach fatigue, and subsequently prevent the inability to control its condition and potential damage to karate athletes