Surface Electromyography Spectral Parameters for the Study of Muscle Fatigue in Swimming.

The purpose of this study was to assess validity, stability and sensitivity, of 4 spectral parameters-median frequency (F _med ), mean frequency (F _mean ), Dimitrov index (DI), and mean instant frequency (F _mi )-in measuring localized muscle fatigue in swimming and to investigate their correlation with the variations of kinematic data and mechanical fatigue. Electrophysiological measures of muscle fatigue were obtained in real-time during a 100 m front crawl test at maximum speed in 15 experienced swimmers, using surface electromyography in six muscles employed in front crawl, while kinematic data of swimming was measured from video analysis. Mechanical fatigue was measured as the difference between muscle strength prior to and immediately after the 100 m front crawl in a dry-land multi-stage isometric contraction test. Statistically significant fatigue ( p < 0.0001) was found for all spectral parameters in all muscles. F _med and F _mean varied between 10 and 25%, DI between 50 and 150%, and F _mi between 5 and 10%. Strong correlation (Pearson r ≥ 0.5) with mechanical fatigue was found for all spectral parameters except for F _mi and it was strongest for F _med and F _mean . From our study, it turns out that F _med and F _mean are more valid and stable parameters to measure fatigue in swimming, while DI is more sensitive.
Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
(Copyright © 2021 Puce, Pallecchi, Marinelli, Mori, Bove, Diotti, Ruggeri, Faelli, Cotellessa and Trompetto.)