Electromyography of paraspinal muscles during self-corrective positions in adolescent idiopathic scoliosis.

Background: Self-corrective exercise is commonly used in the training protocol of patients with adolescent idiopathic scoliosis (AIS). The muscle activation pattern during symmetrical and overcorrection exercises is then explored to guide the treatment.

Objective: To compare the paraspinal muscle activity during three self-corrective positions and the habitual standing in AIS.

Methods: Thirty-three adolescents with double curved scoliosis were examined. The curve type and Cobb's angle were determined from their whole spine X-ray. They adopted habitual standing, symmetrical correction and two overcorrected positions (O1 and O2). The surface electromyography (EMG) was monitored on both sides of paraspinal muscles at the apex areas of scoliotic curves. The EMG ratio between sides was inferred as the corrective effect.

Results: All three self-correction positions produced greater EMG ratios compared with the habitual standing. The greatest EMG ratios were observed during the O1 position at the thoracic curve and the habitual standing at the lumbar curve. Participants with different subtypes of curves exhibited similar patterns of EMG ratios.

Conclusion: From the biomechanical viewpoint, all three self-corrective positions possibly provided therapeutic effects for the scoliotic body regardless of the subtype of scoliosis curves. The O1 position seemed to be most effective for the adjusting activation of thoracic paraspinal muscles. The symmetrical corrective position is otherwise recommended for adjusting the lumbar muscle activation.