Relationship Between Muscle Activity and Force During Suspended Bridge Exercises.

Context: Isometric core stability exercises are commonly used to target muscles of the lumbopelvic-hip complex, including the rectus abdominis (RA) and erector spinae (ES). These exercises can be implemented in rehabilitation protocols to increase muscle strength and endurance. Difficulty can be progressed by modifying the base of support or adding an unstable element. Load cells can be affixed to suspension training devices to measure force exerted through the straps during exercise. The primary purpose of this study was to assess the relationship between activity of the RA and ES to force measured through a load cell fixed to suspension straps during bilateral and unilateral suspended bridge exercises.

Design: Forty asymptomatic, active individuals completed a single laboratory visit.

Methods: Participants completed 2 bilateral suspended bridges and 2 unilateral suspended bridges held to failure. Surface electromyography sensors were placed over the bilateral RA and ES to quantify muscle activity (% maximum voluntary isometric contraction). A load cell was affixed to the suspension straps to measure force exerted through the straps throughout the duration of the exercise. Pearson correlations were used to determine relationships between force and muscle activity of the RA and ES throughout exercise duration.

Results: Force was negatively related to RA muscle activity in bilateral suspended bridges (r = -.735 to -.842, P < .001) and unilateral suspended bridges (r = -.300 to -.707, P = .002 to <.001). Force had a positive relationship with ES muscle activity in bilateral suspended bridges (r = .689 to .791, P < .001) and unilateral suspended bridges (r = .418 to .448, P < .001).

Conclusions: Suspended bridge exercises can be a valuable tool to target posterior abdominal musculature such as the ES to contribute to core stability and endurance. Load cells can be applied during suspension training to quantify the interaction between individuals and the exercise equipment.