Spinal mobility and muscular strength: effects of supine- and prone-lying back extension exercise training

This study compared the effectiveness of supine-lying back extension (SBE) exercise and prone-lying back extension (PBE) exercise on spinal mobility and muscular strength. A 3 (groups) x 4 (time frames) experimental design was used. Thirty-four healthy men (mean age, 23.1 +/- 2.1 years) were randomly assigned to three groups. Subjects in group 1 (n = 11) were trained using the SBE protocol, whereas those assigned to group 2 (n = 12) performed the PBE program. Subjects in group 3 (n = 11) received no exercise training and served as controls. The exercise programs were standardized and administered three times a week for 6 weeks. The spinal range of motion (ROM) and back extension isometric force of all the subjects was evaluated before training, at the end of the third and sixth weeks of the study, and 9 weeks after the end of the exercise training. A two-factor (group and time frame), repeated-measures ANOVA was used to determine significant differences in spinal ROM and back extension isometric force among the groups at the different time frames. The results of the statistical analyses showed progressive increases (p less than .05) in spinal ROM and isometric force after the exercise training; they had increased by 12.6% and 19.2%, respectively, at the end of the sixth week of training. The gain in spinal mobility was completely obliterated nine weeks posttraining. However, the improvement in muscular strength was sustained 9 weeks after the end of physical training. The SBE method was better for improving the spinal ROM, whereas the PBE method was more effective in augmenting muscular strength of the back.