Background: Abdominal exercises (AE) are one of the most popular exercises used in fitness and training programs. Exercising on an unstable surface as opposed to exercising directly on a hard flat surface may enhance the body respond to the instability. To remain balanced the muscle recruitment patterns may change and enhanced muscle response may be required. Methods: Thirty three normal healthy male and female subjects with age between 18-25 years were included in the study. Subjects were asked to perform abdominal crunches on four different surfaces (plinth, Swiss ball, 2-dimensional wobble board and 3- dimensional wobble board) and electromyographic activity of the upper and lower rectus abdominis was noted. Results and Conclusion: Average as well as the peak activity of upper and lower rectus abdominis muscle was found to increase as subject performed on progressively more unstable surface. 

Key words: Abdominal exercises; Swiss ball; 2-Dimensional wobble board; 3-Dimensional wobble board.