Date of Award


Document Type

Scholarly Project

Degree Name

Master of Physical Therapy (MPT)


Physical Therapy

First Advisor

Thomas Mohr


Abdominal Muscles -- physiology; Low Back Pain -- prevention & control


Strengthening of trunk musculature is an important part of prevention and treatment for low back pain. Various exercise machines have been developed to strengthen the trunk muscles. One such machine, the Abdominal Unit, has been marketed by a company in North Dakota, Fitness Plus, Inc. However, there is currently no research to validate the manufacturer's claims as to muscles exercised through the use of their machine.

The purpose of this study was to measure and describe the muscle activity elicited while exercising on the Fitness Plus Abdominal Unit. Telemetried electromyography was used to study muscle activity in the rectus abdominis, internal and external obliques, and the erector spinae.

Fourteen male subjects performed maximal voluntary contractions (MVC) as a baseline of muscle activity. They were then tested during exercise on the Abdominal Unit with three variations: 1) 25 pounds of resistance, 2) maximum resistance, and 3) maximum resistance and the feet stabilized.

The recorded data was then analyzed and the percent of MVC was calculated for each muscle tested. Results showed marked activity in the abdominal musculature with minimal erector spinae activity, during all three exercise variations. Increased resistance elicited increased muscle activity in all muscles tested. The effect of stabilizing the feet produced no consistent results.

The Fitness Plus Abdominal Unit is successful in recruiting the superficial abdominal muscles as per manufacturer's claims indicating that it could be an effective tool for strengthening the abdominal muscles.