Effect of modified bridge exercise on trunk muscle activity in healthy adults: a cross sectional study

Abstract

Design: This is a cross-sectional study.

Setting: University research laboratory.

Participants: Fifteen healthy adults (mean age: 27.47 years) volunteered for this study.

Intervention: The individuals performed standard bridge exercise and modified bridge exercises with right leg-lift (single-leg-lift bridge exercise, single-leg-lift bridge exercise on an unstable surface, and single-leg-lift hip abduction bridge exercise).

Main outcome measures: During the bridge exercises, electromyography of the rectus abdominis, internal oblique, erector spinae, and multifidus muscles was recorded using a wireless surface electromyography system. Two-way repeated-measures analysis of variance (exercise by side) with post hoc pairwise comparisons using Bonferroni correction was used to compare the electromyography data collected from each muscle.

Results: Bilateral internal oblique muscle activities showed significantly greater during single-leg-lift bridge exercise (95% confidence interval: right internal oblique=-8.99 to -1.08, left internal oblique=-6.84 to -0.10), single-leg-lift bridge exercise on an unstable surface (95% confidence interval: right internal oblique=-7.32 to -1.78, left internal oblique=-5.34 to -0.99), and single-leg-lift hip abduction bridge exercise (95% confidence interval: right internal oblique=-17.13 to -0.89, left internal oblique=-8.56 to -0.60) compared with standard bridge exercise. Bilateral rectus abdominis showed greater electromyography activity during single-leg-lift bridge exercise on an unstable surface (95% confidence interval: right rectus abdominis=-9.33 to -1.13, left rectus abdominis=-4.80 to -0.64) and single-leg-lift hip abduction bridge exercise (95% confidence interval: right rectus abdominis=-14.12 to -1.84, left rectus abdominis=-6.68 to -0.16) compared with standard bridge exercise. In addition, the right rectus abdominis muscle activity was greater during single-leg-lift hip abduction bridge exercise compared with single-leg-lift bridge exercise on an unstable surface (95% confidence interval=-7.51 to -0.89). For erector spinae, muscle activity was greater in right side compared with left side during all exercises (95% confidence interval: standard bridge exercise=0.19-4.53, single-leg-lift bridge exercise=0.24-10.49, single-leg-lift bridge exercise on an unstable surface=0.74-8.55, single-leg-lift hip abduction bridge exercise=0.47-11.43). There was no significant interaction and main effect for multifidus.

Conclusions: Adding hip abduction and unstable conditions to bridge exercises may be useful strategy to facilitate the co-activation of trunk muscles.

Keywords: Bridge exercise; Hip abduction; Trunk muscle; Unstable condition.

Figure 1

Placements of EMG electrodes.

Figure 2

Experimental protocol used for the bridge exercises. (A) Bridge exercise (BE), (B) single-leg-lift bridge exercise (SLBE), (C) single-leg-lift bridge exercise on an unstable surface (SLBU), (D) single-leg-lift hip abduction bridge exercise (SLHB).

Figure 3

Differences in IO muscle activity (%MVIC) among bridge exercise (BE), single-leg-lift bridge exercise (SLBE), single-leg-lift bridge exercise on an unstable surface (SLBU), and single-leg-lift hip abduction bridge exercise (SLHB). The right leg was lifted during SLBE, SLBU, and SLHB. *p < 0.05.

Figure 4

Differences in RA muscle activity (%MVIC) among bridge exercise (BE), single-leg-lift bridge exercise (SLBE), single-leg-lift bridge exercise on an unstable surface (SLBU), and single-leg-lift hip abduction bridge exercise (SLHB). The right leg was lifted during SLBE, SLBU, and SLHB. *p < 0.05.