The unstable surfaces of a BOSU® ball and Swiss ball typically have a greater impact on EMG muscle activity during a push up compared to a normal push up done on a flat stable surface. This study's purpose was to determine if performing a push up on a BOSU® ball and on an exercise bench influenced EMG muscle activity when compared to the activity of a push up on a stable surface in females. Eighteen females were recruited from a convenience sample of college students. The pectoralis major, rectus abdominus, and external oblique muscles showed the greatest EMG muscle activity. The posterior deltoid showed the lowest activity. Overall, the push up performed on the bench showed the greatest EMG muscle activity compared to the other types of push ups.