A Novel Electromyographic Approach to Estimate Fatigue Threshold in Maximum Incremental Strength Tests

Area of Science:

• Sports Science
• Exercise Physiology
• Biomedical Engineering

Background:

• Assessing muscular fatigue in athletes during explosive exercises is complicated by minimal changes in traditional metrics.
• Existing methods often fail to detect subtle fatigue variations in single muscles.

Purpose of the Study:

• To develop and validate a novel method for estimating the fatigue threshold in individual muscles.
• To investigate the utility of surface electromyography (sEMG) for this purpose.

Main Methods:

• A maximal incremental half-squat strength test was conducted on 20 participants (10 men, 10 women).
• Surface electromyography (sEMG) data were collected from vastus lateralis, vastus medialis, and rectus femoris muscles.
• Participants performed five incremental intensities up to their one-repetition maximum (1RM).

Main Results:

• A distinct breakpoint, indicating the fatigue threshold, was identified using sEMG data.
• In men, fatigue thresholds occurred at 70.74% (vastus lateralis), 71.48% (vastus medialis), and 72.52% (rectus femoris) of 1RM.
• In women, thresholds were observed at 76.66% (vastus lateralis), 76.27% (vastus medialis), and 72.10% (rectus femoris) of 1RM.

Conclusions:

• Surface electromyography (sEMG) provides a viable, rapid, and noninvasive approach to determine muscle-specific fatigue thresholds.
• This method is effective during maximal half-squat strength testing, offering new insights for athlete assessment.