Test-retest reliability of the electromyographic fatigue threshold for cycle ergometry.

Introduction: The purpose of this study was to determine the intersession reliability of the electromyographic fatigue threshold (EMGFT ) for cycle ergometry.

Methods: On separate occasions, 10 healthy, college-aged men performed an incremental test to voluntary exhaustion on a cycle ergometer. The EMG amplitude vs. time relationships for each power output from the quadriceps femoris muscles were analyzed using linear regression. EMGFT was defined operationally as the average of the highest power output that resulted in a non-significant slope coefficient (P >  0.05) and the lowest power output that resulted in a significant (P <  0.05) positive slope coefficient. The EMGFT values for trials 1 and 2 were used to calculate the intraclass correlation coefficient (ICC).

Results: Overall, the reliability of the EMGFT (ICC2,1  = 0.85; 95% confidence interval 0.49-0.96) was in the "excellent" category.

Conclusions: The EMGFT for cycle ergometry is a reliable measure for assessing muscular fatigue.