The Effect of Fatigue on the Lower Limb Muscle Electromyography Frequency Spectrum in Teen weightlifters during the Snatch and the Clean and Jerk Lift

The aim of this study was to investigate the effect of fatigue on the lower limb muscle electromyography frequency spectrum in teen weightlifters during the snatch and the clean and jerk move. This study was semi-experimental. 15 teen weightlifters with an age range of 12 to 17 years with purposive sampling were selected in coordination with the Ardabil province weightlifting board. A wireless electromyography system with 8 pairs of bipolar surface electrodes used to record the electromyography activity of lower limb muscles during the running (sample rate: 1000 Hz). For doing functional fatigue, each subject performed squat motion as much as possible to load equal to 50% of body weight. Two-way ANOVA was used for statistical analysis (p < 0.05). Results showed that the median frequency of vastus medialis muscle during snatch after fatigue protocol was greater than before it (P=0.023; large effect size). Moreover, the median frequency of semitendinosus muscle during snatch was greater than clean and jerk (P=0.047; Medium effect size). Also, the median frequency of rectus femoris (P=0.021; medium effect size) and biceps femoris (P=0.033; medium effect size) during clean and jerk increased significantly after fatigue compared to before fatigue. The results showed that the frequency spectrum of the lower limb muscles has different responses in two movements of clean and jerk and snatch before and after fatigue. For this reason, the necessity of performing special exercises for each muscle is necessary for various techniques.