Trunk muscle activity during different variations of the supine plank exercise.

BACKGROUND: Exercises providing neuromuscular challenges of the spinal muscles are desired for core stability, which is important for workers with heavy manual labour as well as people recovering from back pain.

PURPOSE: This study evaluated whether using a suspended modality increases trunk muscle activity during unilateral or bilateral isometric supine planks.

DESIGN: Cross-sectional.

METHODS: Twenty university students participated in this cross-sectional study. Each subject performed four different conditions: bilateral stable supine plank, unilateral stable supine plank, bilateral suspended supine plank and unilateral suspended supine plank. Surface electromyography (EMG) signals were recorded for the upper rectus abdominis (UP ABS), lower rectus abdominis (LOW ABS), external oblique (OBLIQ) and lumbar erector spinae (LUMB). Peak EMG of the filtered signals were normalized to the maximum voluntary isometric contraction (MVIC).

RESULTS: No differences between exercises were found for UP ABS, LOW ABS and OBLIQ muscle activity. The unilateral suspended supine plank provided the highest LUMB activity (20% of MVIC) whiles the bilateral stable supine plank provided the lowest activity (11% of MVIC).

CONCLUSIONS: The combination of unilateral variations with a suspended support provides the greatest LUMB muscle activity, while using these variations separately only provides advantages when compared with regular planks.