Date of Award


Degree Name

Master of Arts


Human Performance and Health Education

First Advisor

Dr. Timothy J. Michael

Second Advisor

Dr. Nicholas Hanson

Third Advisor

Dr. Sangwoo Lee


Instability, electromyography, side bridge, core, exercise

Access Setting

Masters Thesis-Open Access


Training the musculature of the core continues to be perceived as an essential component of conditioning and rehabilitation settings (11). A popular way to train the core is with the use of instability devices, such as Swiss ball or suspension trainer. However, there is limited research on the effects of these devices on core muscle activity. The purpose of this study was to examine core muscle activity during side bridge variations with and without instability devices (Floor, Swiss Ball, and TRX) through electromyography (EMG) of the rectus abdominis, external oblique, erector spinae, and latissimus dorsi. 39 participants performed three variations of a side bridge; one on the floor, one with their feet elevated on a swiss ball, and one with feet suspend in a TRX suspension trainer. Each bridge variation was held for 5 seconds and repeated three times. Prior to performing the side bridges, participants completed a maximal voluntary isometric contraction (MVIC). Root mean square (RMS) values for each side bridge were normalized to the MVIC and reported as a percentage of MVIC. Significant increases in muscle activation occurred with the use of the instability devices. Mean ± SD %MVIC was significantly higher on the ball (B) and TRX (T) when compared to the floor (F) in the rectus abdominis (F: 21.77±11.86; B: 29.7±15.61; T: 31.73±18.52) external oblique (F: 32.92±13.64; B:40.09±24.44; T: 38.0±18.52), and latissimus dorsi (F: 7.03±4.49; B: 12.18±9.07; T: 12.18±7.26). It was concluded that instability devices may be beneficial in training the core musculature.