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

Abstract

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 6 SEM: age, 22.6 6 1.2 years; mass, 68.6 6 10.4 kg; and height, 1.76 6 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 6 8 W) for the exercise test. In addition, a mean end-exercise heart rate (155 6 8 b•min 21 ) corresponded to 79 6 4% of the age-predicted heart rate using the formula 220-age. Separate paired t tests for the slope (t[8] 5 0.929 p 5 0.38) and y-intercept (t[8] 5 0.368, p 5 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.

A Comprehensive Examination of Age-Related Lower Limb Muscle Function Asymmetries across a Variety of Muscle Action Types

“…For the majority (15 of 17) of the presently assessed variables (across modes and velocities), there were no statistically or functionally (≥10%) significant limb differences for either age group. These findings are similar to previous research that found little to no power, strength, or balance functional asymmetries in the quadriceps for young, healthy adults [ 18 , 19 , 21 , 36 , 37 , 38 ]. However, it should be noted that some of these studies found statistically significant asymmetries in isometric peak torque [ 18 , 19 ].…”

“…Prior studies [ 5 , 18 , 20 ] have also involved either single- or multi-joint testing, but have not examined comparisons of both. Moreover, other studies [ 5 , 21 , 22 , 23 ] involved either young or older adult groups, but have generally lacked a comparison of the two age groups. The singularity of the earlier studies regarding aging, asymmetries, and joint comparison limits the ability to determine comprehensive age-related effects on muscle asymmetries.…”