Test - Retest Reliability Of EMG FT During Cycle Ergometry

Abstract

The electromyographic fatigue threshold (EMGFT) can be defined as the power output that can be maintained for an extended period of time without electromyographic (EMG) evidence of fatigue. PURPOSE: To determine the reliability of the EMGFT test over three trials in college-aged women. METHODS: Eleven healthy women (mean±SD; age: 22.2±4.1 years; height: 167.8±8.4 cm; weight: 63.7±11.1 kg) performed a discontinuous cycle-ergometer test to determine her EMGFT using bipolar surface electrodes placed on the vastus lateralis of the right thigh midway between the greater trochanter and the lateral condyle of the femur. Four 120-s work bouts (ranging from 75 to 225 W) were completed at a cadence of 70 rpm. EMG amplitude values were averaged over 5-s intervals for each work bout. Simple linear regression was used to determine relationships (slopes) for the EMG amplitude versus time relationships during each subject's work bout. Resulting slopes from each successive work bout were plotted over the corresponding power output, and the Y-intercept of this relationship was the subjects predicted EMGFT. This EMGFT test was performed three times; each separated by four weeks. A one-way repeated measures analysis of variance was used to determine the intraclass correlation coefficient (ICC) and standard error of the measurement (SEM). RESULTS: There was no systematic variability over the three trials (p=0.268). The ICC observed in the current study was 0.71 and the SEM was 22.3 W. CONCLUSIONS: The ICC of 0.71 is higher than previously reported in men (0.65) by Pavlat et al. (1993). The SEM of 22.3 W is 18.8% of the grand mean EMGFT across all trials. These findings suggested that the EMGFT test was relatively reliable for college-aged women over a 2 month period.Table 1-EMG: FT mean and standard error of the measurement for each trial (in watts)