['The aim of the current study is to determine if performing push up exercise variations on an unstable surface (Swiss ball) influences EMG amplitude of the scapulothoracic muscles when compared with a stable surface (Bench).', 'Ten males were recruited from a convenience sample of college students. Surface electromyograms were recorded from the upper trapezius, lower trapezius, serratus anterior and biceps brachii while performing push up exercises with the feet or hands placed on a bench and separately on a Swiss ball. A push up plus exercise was also evaluated with hands on the different support surfaces.', 'There was no statistically significant (p<0.05) difference in mean EMG amplitude on a Swiss ball when compared with the same exercise performed on a bench. Significant differences in muscle activity were seen in the upper trapezius and serratus anterior as a result of changes in foot position relative to hand position irrespective of surface stability.'] Does an unstable support surface increase scapulothoracic stabilizing muscle activity during push up and push up plus exercises?