A Novel Electromyographic Approach to Estimate Fatigue Threshold in Maximum Incremental Strength Tests
in Motor ControlEvaluation of muscular fatigue thresholds in athletes performing short-duration and explosive exercises is difficult because classic parameters do not suffer large variations. Therefore, the aim of this study was to develop a new method to estimate the fatigue threshold in single muscles. Our approach is based on electromyographic data recorded during a maximum incremental strength test until the one repetition maximum is reached. Ten men and 10 women performed a half-squat strength test consisting of five incremental intensities of one repetition maximum. Neither heart rate nor blood lactate concentrations showed significant differences at the various intensities tested. Surface electromyographic activities of vastus lateralis, vastus medialis, and rectus femoris were recorded, finding a break point corresponding to the fatigue threshold occurring in men at 70.74%, 71.48%, and 72.52% of one repetition maximum, respectively. In women, break-point values were 76.66% for vastus lateralis, 76.27% for vastus medialis, and 72.10% for rectus femoris. In conclusion, surface electromyography could be a useful, rapid, and noninvasive tool to determine the fatigue threshold of independent muscles during a maximal half-squat strength test.
Aragón-Vela and Huertas are with the Dept. of Physiology, Faculty of Pharmacy and Sport Sciences, University of Granada, Granada, Spain. Aragón-Vela, Casals-Vázquez, and Huertas are with the Dept. of Physiology, Faculty of Sport Sciences, University of Granada, Granada, Spain. Plaza-Díaz and Fontana are with the Dept. of Biochemistry and Molecular Biology II, Faculty of Pharmacy, University of Granada, Granada, Spain. Aragón-Vela, Barranco-Ruiz, Casals-Vázquez, Plaza-Díaz, Casuso, Fontana, and Huertas are with the Institute of Nutrition and Food Technology “José Mataix,” Biomedical Research Centre, University of Granada, Granada, Spain. Barranco-Ruiz is also with the School of Physical Culture, School of Health Sciences, National University of Chimborazo, Riobamba, Chimborazo, Ecuador. Plaza-Díaz and Fontana are also with the Instituto de Investigación Biosanitaria de Granada (ibs. Granada), Granada, Spain.
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