Effects of the Abduction Resistance of the Hip Joint during Bridge Exercise in Patients with Chronic Back Pain: A Cross-Over Study
Purpose: This study examined the effects of the levels of resistance on the muscle activities around the hip and spine during bridge exercise with hip abduction resistance in patients with chronic back pain.
Methods: A cross-over study design was used. Twenty subjects with low back pain were enrolled in this study. The subjects performed bridge exercise with hip abduction resistances (20 mmHg, 40 mmHg, and 60 mmHg). An elastic band was used to provide resistance. The surface electromyography device was used to measure the activity of the erector spinae, biceps femoris, gluteus maximus, and gluteus medius. The Root Mean Square (RMS) was calculated and the EMG signals collected were normalized to the percentage Maximal Voluntary Isometric Contraction (%MVIC). One way repeated measures ANOVA was applied to examine the differences.
Results: The muscle activity of the gluteus maximus and gluteus medius increased significantly with in increasing resistance level. There was significant difference of muscle activity in biceps femoris with resistance level between 20 mmHg and 40 mmHg, but there was no significant difference in other resistance levels. There was no significant difference according to resistance level in the erector spinae. The muscle activity ratios of the gluteus medius/erector spinae and gluteus maximus/erector spinae increased significantly with increasing resistance strength.
Conclusion: The different levels of abduction resistance for hip abduction during bridge exercise will help activate the gluteus maximus selectively in patients with chronic back pain.