Rafael F. Escamilla, Clare Lewis, Amanda Pecson, Rodney Imamura, James R. Andrews

Prone, supine, and side position exercises are employed to enhance core stability. Overall core muscle activity would be greater in prone position exercises compared with supine and side position exercises. Controlled laboratory study. Eighteen men and women between 23 and 45 years of age served as subjects. Surface electrodes were positioned over the upper and lower rectus abdominis, external and internal obliques, rectus femoris, latissimus dorsi, and lumbar paraspinals. Electromyography data were collected during 5 repetitions of 10 exercises, then normalized by maximum voluntary isometric contractions (MVIC). Differences in muscle activity were assessed using 1-way repeated-measures analysis of variance, while t tests with a Bonferroni correction were employed to assess pairwise comparisons. Upper and lower rectus abdominis activity was generally significantly greater in the crunch, bent-knee sit-up, and prone position exercises compared with side position exercises. External oblique activity was significantly greater in the prone on ball with right hip extension, side crunch on ball, and side bridge (plank) on toes compared with the prone and side bridge (plank) on knees, the crunch, or the bent-knee sit-up positions. Internal oblique activity was significantly greater in the prone bridge (plank) on ball and prone on ball with left and right hip extension compared with the side crunch on ball and prone and side bridge (plank) on knees positions. Lumbar paraspinal activity was significantly greater in the 3 side position exercises compared with all remaining exercises. Latissimus dorsi activity was significantly greater in the prone on ball with left and right hip extension and prone bridge (plank) on ball and on toes compared with the crunch, bent-knee sit-up, and prone and side bridge (plank) on knees positions. Rectus femoris activity was significantly greater in the prone on ball with left hip extension, bent-knee sit-up, or prone bridge (plank) on toes compared with the remaining exercises. Prone position exercises are good alternatives to supine position exercises for recruiting core musculature. Side position exercises are better for oblique and lumbar paraspinal recruitment. Because high core muscle activity is associated with high spinal compressive loading, muscle activation patterns should be considered when prescribing trunk exercises to those in which high spinal compressive loading may be deleterious.