Date of Award


Document Type

Scholarly Project

Degree Name

Master of Physical Therapy (MPT)


Physical Therapy

First Advisor

Thomas Mohr


Abdominal Muscles -- physiology


People have developed an obsession with flattening their stomachs and slimming down their waistlines. The so called "ab machines" have become the most popularly purchased home exercise tools. Although numerous electromyographic (EMG) analysis studies have been done on various forms of equipment-free abdominal exercise, little research has been done to evaluate the effectiveness of equipment-aided exercise. The purpose of this study was to analyze and evaluate any differences in EMG activity between three abdominal exercises: the traditional crunch, the crunch on a ball, and utilization of a prone rolling machine (AbSlide®).

Thirty, healthy subjects between the ages of 19 and 29 performed a maximal voluntary contraction (MVC) and two trials of each abdominal exercise. Abdominal EMG activity was recorded through surface electrodes and then normalized to percent MVC (%MVC) by comparing the muscle activity in the trial with the muscle activity during the reference MVC.

Results of this study showed no significant difference in %MVC between the upper rectus abdominis, lower rectus abdominis, and external oblique during the crunch, crunch on a ball, and the AbSlide®. However, equipment-aided abdominal strengthening could be utilized to add variety or motivation to a current strengthening routine provided they are not contraindicated by a person's health status.