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Analyzing How Skinfold Thickness Affects Log-Transformed EMG Amplitude-Power Output Metrics
Matthew J Kraydich1,2, Jacob Gonzalez1,2, Marcus A Ziebold1,2
1Physical Therapy Program, Department of Health Care Sciences, Wayne State University, College of Pharmacy and Health Sciences, Detroit, MI 48201, USA.
Background:
The purpose of this study was to determine whether accounting for skinfold thickness would reduce the variability observed on a subject-by-subject basis for the y-intercept and slope terms derived from the log-transformed EMG amplitude-power output relationship. We hypothesized that using skinfold thickness as a covariate would reduce the subject-by-subject variability in the y-intercept and slope terms and, therefore, indicate potential mean differences between muscle groups.
Methods:
Subjects had the skinfold from their three superficial quadriceps femoris muscles measured and then EMG electrodes placed over the three muscles. Thereafter, each subject performed an incremental single-leg knee-extensor ergometer exercise test to voluntary exhaustion.
Results:
The results indicated that using skinfold thickness as a covariate did not change the statistical outcome when comparing the mean values for the y-intercept or slope terms across the three superficial quadriceps femoris muscles.
Conclusion:
These findings suggest that there may be other factors that are influencing the subject-by-subject variability for the y-intercept and slope terms, respectively.
