A comparison of critical force and electromyographic fatigue threshold for isometric muscle actions of the forearm flexors

The purpose of this study was twofold: (1) to determine if the mathematical model used for estimating the EMGFT during cycle ergometry was applicable to isometric muscle actions; and (2) to compare the mean torque level from the CF test to that of the EMGFT test. The CF was defined as the slope coefficient of the linear relationship between total “isometric work” (Wlim in N m s) and time to exhaustion (Tlim). The EMGFT was defined as the y-intercept of the isometric torque versus EMG fatigue curve slope coefficient relationship. There was a significant (p < 0.05) mean difference between CF (6.6 ± 3.2 N m) and EMGFT (10.9 ± 4.7 N m). The results of the present study suggested that, during isometric muscle actions of the forearm flexors, fatigue thresholds estimated from the Wlim versus Tlim relationship (CF) are different from those estimated from electromyographic fatigue curves (EMGFT).

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