An Investigation of the Effect of Quadriceps Fatigue on Electromyography Frequency Spectrum in the Lower Limb Muscles during Apdoliochagi in Elite Men

The frequency spectrum of electromyography is one of the important indicators to identify the amount of fatigue in the muscles. The aim of this study was to evaluate the effect of quadriceps fatigue on the electromyography frequency spectrum in lower limb muscles in elite men during the Apdoliochagi. 14 male taekwondo players (mean age of 24.50±1.74 years) with at least 3 years of participation in national competitions were voluntarily and purposively selected with coordination of the taekwondo board of Ardabil province. A wireless electromyography system with 8 pairs of bipolar surface electrodes was used to record the electromyography activity of lower limb muscles during the Apdoliochagi (sample rate: 1000 Hz). Paired t test was used to analyze within-group differences (P≤0.05). Results showed a significant decrease in the frequency spectrum of electromyography in vastus medialis (P=0.042, d=0.93),vastus lateralis (P=0.044, d=0.90), rectus femoris (P=0.003, d=1.18), biceps femoris (P=0.020, d=1.13), semi tendentious (P=0.029, d=0.94) and gluteus medius (P=0.023, d=1.06) after fatigue compared with the period before fatigue. The results showed a significant decrease in the frequency spectrum of electromyography in muscles of the hip and gluteus medius after quadriceps fatigue. Although such results were not obtained in the muscles of tibia anterior and gastrocnemius, this difference can be attributed to the differences in muscle mobility in terms of motor behavior. So, coaches and players are recommended to focus on those exercises which increase endurance of quadriceps, hamstring and gluteus medius.