The Science
W.A. Sands, J.R. McNeal, F.Koch, Motor Behavior Research Laboratory.
University of Utah, Salt Lake City, UT
An electromyographical investigation was undertaken to compare the activity of the upper and lower rectus abdominus during the execution of several common abdominal conditioning exercises. Surface EMG recordings were collected at a sambling rate of 100 Hz, amplified and the average root-mean square calculated in 13 active college age subjects. The average of three trials of each exercise was used for analysis. It was discovered that the nature of the EMG recording for each exercise fell into one of two descriptions, a signal described by continuous, relatively low amplitude activity throughout both concentric and eccentric portions of the exercise. The exercises were therefore compared only with those demonstrating the same characteristic EMG recording. It was found that within the continuous-activation group of exercises, the upper rectus abdominus showed no significant differences between the typical flay-lying crunch (FLC), ab-roller exercise (ROL), Ab Mat™ (Mat), and ab-roller combined with Ab Mat™ (MROL) exercises. The lower rectus abdominus however showed that the MAT elicited greater activation than the ROL and MROL, and the FLC was greater than the MROL. The full situp (FSU) and the Ab Bench™ (BEN) EMG recordings were characterized by higher amplitude, discrete phasic
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