Limited range-of-motion lumbar extension strength training.

The purpose of this study was to evaluate the effect of limited range-of-motion (ROM) resistance training on the development of lumbar extension strength through a 72 degrees ROM. Thirty-three men and 25 women (age = 30 +/- 11 yr) were randomly assigned to one of three training groups or a control group (C; n = 10) that did not train. Training was conducted once per week for 12 wk and consisted of one set of 8-12 repetitions of variable resistance lumbar extensions until volitional fatigue. Group A (n = 18) trained from 72 degrees to 36 degrees of lumbar flexion; group B (n = 14) from 36 degrees to 0 degree of lumbar flexion; and group AB (n = 16) from 72 degrees to 0 degree of lumbar flexion. Prior to and after training, isometric lumbar extension torque was assessed at 72 degrees, 60 degrees, 48 degrees, 36 degrees, 24 degrees, 12 degrees, and 0 degree of lumbar flexion. Analysis of covariance showed that groups A, B, and AB increased lumbar extension torque (P less than or equal to 0.05) at all angles measured when compared with C. The greatest gains in torque were noted for groups A and B in their respective ranges of training but A and B did not differ from AB (P greater than 0.05) at any angle. These data indicate that limited ROM lumbar extension training through a 36 degrees ROM is effective for developing strength through 72 degrees of lumbar extension.