Dissertations and Theses @ UNI


Open Access Thesis


Abdomen--Muscles; Swiss exercise balls; Academic theses;


The purpose of the study is to determine if there is a difference in muscle activation when performing three common abdominal exercises, isolating the rectus abdominis and external obliques, on a contoured gym ball compared to a flat surface. Thirty female volunteers, aged 19-24, performed an abdominal crunch (AC), an abdominal crunch with a twist (ACWT), and a side-lying crunch (SC) on both a flat table and on a gym ball. A stabilization base was utilized to control instability when on the ball. Exercises were performed in random order to prevent the first exercise to avoid the first exercise from being consistently higher and the final being consistently lower due to fatigue. Electromyography was used to record the muscle activation (root mean square) from surface electrodes placed on the right rectus abdominis and the external obliques. Statistics were analyzed using a repeated measures t-test comparing the activation from the exercises performed on the table to exercises performed on the ball using the average value of four repetitions. Results of the study indicated that there were no differences between the modes of exercise among any of the exercises. Based on the results, it can be concluded in this study that common exercises performed on a gym ball versus a flat stable surface does not increase the activity of the rectus abdominis and abdominal oblique muscles. The pre-stretch that occurs in the abdominal muscles does not increase the activation compared to that obtained when the exercise is done on a flat and stable surface.

Year of Submission


Degree Name

Master of Arts


School of Health, Physical Education, and Leisure Services

First Advisor

Forrest Dolgener

Second Advisor

Kevin Finn

Third Advisor

Richard Williams


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Date Original


Object Description

1 PDF file (41 leaves)



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Kinesiology Commons