Log-Transformed Electromyography Amplitude Power Output Relationship: Nondominant vs. Dominant Limb

Boccomino, HL, Daoud, BT, Hudas, A, North, WA, and Malek, MH. Log-transformed electromyography amplitude power output relationship: nondominant vs. dominant limb. J Strength Cond Res 36(3): 851-856, 2022-Findings from studies that examine bilateral differences between the nondominant and dominant limb during whole-body (i.e., cycle ergometry) are equivocal. This may, in part, be because of the mode of exercise (i.e., whole-body) and how the data are analyzed. Surface electromyography (EMG) is a noninvasive method of examining motor unit recruitment and activation during exercise. The log-transformed electromyography amplitude power output relationship provides y-intercept and slope terms on a subject-by-subject basis that can therefore be statistically analyzed. The purpose of this study, therefore, was to identify potential differences in the muscle for the nondominant and dominant limb using the log-transformed EMG amplitude power output relationship for continuous exercise that isolates the quadricep femoris muscles. Nine healthy college-aged men (mean ± SEM: age, 22.6 ± 1.2 years; mass, 68.6 ± 10.4 kg; and height, 1.76 ± 0.03 m) volunteered as subjects for the current study. Each subject visited the laboratory on a single occasion, had EMG electrodes placed on their rectus femoris muscle for their nondominant and dominant limb, and performed an incremental double-leg knee-extensor ergometry to voluntary exhaustion. The subjects achieved a mean power output (75 ± 8 W) for the exercise test. In addition, a mean end-exercise heart rate (155 ± 8 b·min-1) corresponded to 79 ± 4% of the age-predicted heart rate using the formula 220-age. Separate paired t tests for the slope (t[8] = 0.929 p = 0.38) and y-intercept (t[8] = 0.368, p = 0.72) terms revealed no significant mean differences between the 2 limbs. The results of the present study indicate that there are no differences in muscle activation between the nondominant and dominant limbs for continuous exercise that isolates the muscle.