Abstract
CONTEXT: Leg/knee exercise has been extensively used to study the electromyographic (EMG) activity of the quadriceps muscle group. However, conducted studies have several limitations related to methodology. AIMS: To assess the effect of performance level on the EMG activity of the vastus lateralis (VL) muscle of the dominant thigh (right) during the performance of leg/knee extension exercise with 30 repetition maximum load. Thigh dominance was based on the result of leg dynamometer. SETTING AND DESIGN: The study was a cross-sectional study, and data collection was conducted in Indira Gandhi Institute of Physical Education and Sports Sciences, University of Delhi, India. MATERIALS AND METHODS: Healthy intercollegiate-level male sportspersons (n = 19, age = 19.84 ± 2.1 years, height = 171.38 ± 8.48 cm, and weight = 70.42 ± 13.8 kg) were randomly selected as the subjects. Leg extension exercise was performed on Cybex VR1 leg curl exercise device and EMG data were acquired using a 4-Channel Wireless EMG BIOPAC Inc. MP150 system. A criterion called relative impulse (RI) was developed. Based on the magnitude of RI of the subject, nine subjects were enlisted and were equally divided into high-performance (HP), mid-performance (MP), and low-performance (LP) groups. The raw EMG signals were quantified, and time-domain (root mean square [RMS] and integrated EMG [IEMG]) and frequency-domain variables (Median Frequency [MDF] and Mean Frequency [MNF]) were derived with the help of? MATLAB. STATISTICAL ANALYSIS USED: One-way analysis of variance and least significant differences (at P RESULTS: All three groups (HP, MP, and LP) displayed a declining pattern in the EMG activity of the VL in the selected variables, except MP group in the MDF, MNF, and RMS. Significant effect of performance level was observed between LP and HP groups and between MP and HP groups in MDF and MNF (P CONCLUSION: The findings are useful for understanding muscular fatigue as they focus on its electrophysiological aspect.
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