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The purpose of this study was to compare electromyographic (EMG) activity of the abdominal muscles between the crunch exercise and five other popular abdominal exercises. Surface EMG recordings of four muscles (upper rectus, lower rectus, external oblique, and internal oblique) of the anterior abdominal wall were collected and analyzed on 20 healthy, male volunteers. EMG activity was recorded during execution of the abdominal crunch, the sit-up, and exercises performed with the Abflex machine, the AbRoller, the Nordic Track Ab Works, and the Nautilus crunch machine. The results indicate that the crunch exercise is comparable to the five other abdominal exercises with respect to muscle activation of the internal and external abdominal oblique muscles. Activation of the upper rectus abdominal muscles appears to be best achieved with the Abflex machine, whereas the crunch exercise is superior to the sit-up for activation of the upper and lower rectus abdominal muscles.
G.M. Beim is with The Hughston Clinic, 214 E. Denver Ave., Gunnison, CO 81230. J.L. Giraldo, D.M. Pincivero, and M.J. Borror are with the Neuromuscular Research Laboratory, University of Pittsburgh, Pittsburgh, PA 15261. F.H. Fu is with the Center for Sports Medicine and Rehabilitation, University of Pittsburgh.