Quantified Rotational Strength Training: Preliminary Study of an Alternative Method for Idiopathic Scoliosis Management

Abstract

Idiopathic scoliosis patient's posterior spinal muscles are physiologically different than normal suggesting involvement with the etiology or pathogenesis of idiopathic scoliosis. The purposes of this study were to accurately quantify rotation strengths before and after strength training. Nine patients (8 female, 1 male), average age 13 years 1 month, average major Cobb 35º (19º-59º), seven with predominant thoracic and two thoracolumbar curves were studied before strength training; five were studied after strength training. Isometric testing was done in both high and low force arcs at five pre-rotated trunk positions, 36º, 18º, and 0º. Progressive, concentric and eccentric, isotonic strength training in high and low force 40º arcs was done two times weekly for 4 months. Strength was normalized to lean body weight, Nm/LBW. Paired t-tests were used, alpha set at 0.05. There were no significant differences between convex and concave side strengths at baseline. Following strength training both convex and concave strengths were significantly increased except on the convex side of the low force arc. The average strengthening for the 10 pre and post strength training positions was 37%. Only Mooney et al have reported baseline rotational trunk asymmetry, 12 to 47%, but their methodology was not specified. In twenty health, young adult controls we found trunk asymmetry up to 30% (companion validation study). Rotational trunk strength was not asymmetrical at baseline and significant strengthening was accomplished in four months. Whether or not rotational trunk strengthening is a useful treatment for smaller idiopathic scoliosis curves is yet to be determined.