Date of Award


Document Type

Scholarly Project

Degree Name

Master of Physical Therapy (MPT)


Physical Therapy

First Advisor

Mark Romanick


Abdominal Muscles -- physiology; Exercise -- physiology


As the second most common reason for visits to primary care doctors, and a symptom that affects 80% of the general United States population, low back pain and its' treatment is a burdening cost on the American economy every year. Various spinal stabilization exercises have emerged as a means to treat low back pain. One of the most recent fonns of these stabilization exercises used in the physical therapy arena is Pilates, a fonn of dynamic spinal stabilization. Although numerous electromyographic (EMG) studies have been completed on abdominal exercises for spinal stabilization, minimal scientific research can be found on the efficacy of Pilates equipment in this realm. The purpose of this study is to analyze and evaluate the EMG activity in the rectus abdominis, external obliques, and internal obliques using four abdominal exercises: the abdominal crunch on a ball, the abdominal crunch with rotation on a ball, the abdominal crunch on the Pilates Multi-Chair, and the abdominal crunch with rotation on the Pilates Multi-Chair.

Fourteen, healthy subjects between the ages of 18 and 45 years of age performed a maximal voluntary contraction (MVC) and one trial 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 a significant difference in % MVC among exercises in the left external oblique, upper rectus abdominis, and lower rectus abdominis. There was no significant difference in % MVC among exercises in the right external oblique, and the right and left internal obliques. In general, exercises on the ball produced a higher % MVC in the rectus abdominis and the exercises on the Pilates Multi-Chair produced a higher % MVC in the external obliques.