Electromyography and peak torque analysis in football players as indicators of fatigue during isokinetic concentric contractions of the rectus femoris

Abstract

Background: This study investigates the potential of electromyographic (EMG) analysis using the Bitalino device in combination with peak torque measurement to evaluate muscle fatigue during isokinetic concentric contractions of the rectus femoris muscle in football players. By analysing muscle activity in real-time, EMG provides valuable insights into the physiological responses of muscles under exertion, paving the way for targeted interventions to improve athletic performance. This approach offers a non-invasive and efficient method to monitor fatigue levels, enabling the optimization of training regimens, injury prevention strategies, and overall performance enhancement. The integration of EMG analysis with real-time data from peak torque measurements holds significant promise for refining personalized training protocols tailored to the unique needs of each athlete. Methods: Five male football players from the U18 and U19 teams of Belenenses participated. Athletes performed six maximal concentric dynamic contractions of both knee extension and flexion on a Biodex System 4 isokinetic dynamometer. EMG signals were captured through surface electrodes, and peak torque was recorded. EMG data underwent processing to compute root mean square (RMS) and mean frequency (MNF) during contractions. Results: The analysis revealed a correlation between peak torque and EMG variables. Specifically, in 40% of the subjects, peak torque decreased while RMS increased, and MNF decreased as fatigue set in. This trend was particularly pronounced in the dominant leg for most athletes. Additionally, the dominant leg displayed lower EMG (mV) variability, potentially reflecting greater energy efficiency and muscle coordination compared to the non-dominant leg.Conclusion: The identified 40% correlation represents an important preliminary finding, suggesting a relationship between peak torque and EMG variables that may serve as indicators of fatigue during dynamic contractions in a subset of this sample. The observed energy efficiency in the dominant leg underlines the potential impact of muscle coordination and usage frequency on performance. However, the small sample size limits the generalizability of these findings. Expanding future research to include a larger cohort and a broader range of athletic activities is essential for validating these results and refining the application of EMG and peak torque analysis in sports performance optimization.