Date of Award

2007

Document Type

Scholarly Project

Degree Name

Doctor of Physical Therapy (DPT)

Department

Physical Therapy

First Advisor

David Relling

Keywords

Abdominal Muscles; Electromyography; Low Back Pain

Abstract

Background and Purpose. Currently, stationary bicycles do not incorporate exercise for the abdominal and low back musculature. An experimental stationary bicycle, the Magnus Cycle, has been developed to increase trunk muscle activation and, at the same time, provide aerobic conditioning. The purpose of this study is to assess the activity of the rectus abdominus, external oblique, erector spinae, rectus femoris and biceps femoris muscles during a stationary cycling setting and during a tilt-in-space setting of the Magnus Cycle.

Subjects. Sixteen subjects, both men and women, between the ages of 18 and 30 participated in this study.

Methods. Surface electromyography (EMG) was used to assess muscle activity from the rectus abdominus, external oblique, erector spinae, rectus femoris, and biceps femoris muscles during each phase of stationary and oscillating exercise. The raw EMG signal was rectified, smoothed and normalized to the respective muscle maximal voluntary contraction prior to data analysis. A repeated measures t-test was utilized to assess differences in EMG activity between minutes one and three of stationary cycling. DIfferences in the oscillating condition for forward and backward tilt was assessed using a repeated measures ANOVA, alpha = 0.05. For trials without differences between oscillations, one way ANOV A was performed to determine differences between stationary, foot forward, and foot backward tilt conditions.

Results. In the feet forward position, the rectus abdominis, external obliques, and rectus femoris demonstrated significantly higher EMG activation compared to both the stationary and feet backward conditions (p<.05). Activity of the erector spinae and biceps femoris muscles were not affected by the feet forward position. However, in the feet backward position, the erector spinae and biceps femoris muscles demonstrated significantly higher EMG activity compared to the stationary position and feet forward positions (p<.05). The rectus abdominis, external obliques, and rectus femoris muscles were not affected by the feet backward condition.

Discussion and Conclusion. The tilting Magnus Cycle significantly enhances activation of the rectus abdominis, external oblique, erector spinae, rectus femoris, and biceps femoris muscles compared to stationary cycling. The enhanced trunk muscle activity may make the Magnus Cycle a better option for a quicker, more beneficial workout than standard stationary bicycles.

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