Date of Award


Document Type

Scholarly Project

Degree Name

Doctor of Physical Therapy (DPT)


Physical Therapy

First Advisor

Thomas Mohr


Electromyography; Self-Help Devices; Walking


Purpose: The purpose of this study is to analyze the amount of muscle activity of the rectus abdominis and external obliques during the gait cycle with the use of forearm crutches and three different weight bearing statuses. Subjects: Seven female adults were recruited from the University of North Dakota Physical Therapy program. Inclusion criteria: between the ages of 19 and 40 years of age, current physical therapy students, and healthy with no current upper or lower extremity injuries.

Instrumentation: The EMG data was collected by the Noraxon Telemyo 900 telemetry unit and analyzed using the MyoResearch XP software. Six Vicon MX40 infrared cameras were used to capture the marker motion. The Vicon Polygon 3.1 software was used to qualitatively analyze all of the motion and EMG data.

Procedure: Prior to beginning the trials, surface electrodes were placed over the right and left rectus abdominis and right and left external oblique muscles to record the EMG activity. A MVC was performed using an isometric sit-up to establish a normalization baseline. Reflective markers were placed on bony prominences according to the Plug-in-Gait Marker Placement. Participants were fitted for forearm crutches and were allowed to practice a swing-to three point gait prior to the trials. Each participant performed two trials of each weight bearing status.

Data Analysis: The EMG data from the crutch walking trials was compared with the EMG data from the MVC trials. The results were represented as a percent of the MVC. The EMG data was synchronized with the motion analysis data and displayed in graph form which shows the stickman figure along with the muscle activity during each point in time during the walking trial. This was used to qualitatively describe when each muscle was active during the gait cycle.

Results: The quantitative assessment of EMG showed that both the rectus abdominis and the external oblique muscle groups were the most active during the non-weight bearing gait pattern. Activity between the right and left muscle groups was similar in amplitude. The qualitative assessment showed that both the rectus abdominis and the external obliques were the most active during the swing phase of a gait pattern.

Conclusion: The abdominal musculature is active during crutch walking throughout the gait cycle. Physical therapists can benefit from the results of this study by evaluating the abdominal musculature strength during the examination prior to assigning an assistive device and by implementing core strengthening into the rehabilitation phase for those individuals who demonstrate weakness.