PURPOSE: Aim of this study was to investigate effects of 1) regular back extensor strength training as opposed to balance training, and 2) the influence of the sequence of both training types on postural control, force, and muscle efficiency. METHODS: Twenty-six young, healthy subjects were investigated at baseline, 1 month and 2 months later. At each examination, subjects completed a posturographic, balance skill, and isometric maximum voluntary (MVC) back extension testing, including surface electromyographic (SEMG) recordings. After baseline evaluation, subjects were assigned to either daily strength training or balance training. After 1 month, the type of training was exchanged between groups. RESULTS: After 1 month, back extensor strengthening led to decreased postural stability on hard surface, whereas there were no change after balance skill training. Analysis of the low- and high-frequency components of the sway signal revealed that strength training increased control efforts as indicated by an increased high-frequency component in order to maintain postural stability and unchanged low-frequency component. Balance skill training, however, increased postural stability as indicated by a decreased low-frequency component. The control effort remained unchanged. After completing either sequence of training, all postural parameters remained unchanged in both groups. Muscular efficiency as measured by SEMG root mean square during a standardized motor skill task revealed improved muscle economy regardless of the type of training. Back extension torque improved in both groups. CONCLUSION: To avoid reduction of postural stability in rehabilitation processes, we recommend to include antagonist muscles in a comprehensive strength training regime or balance skill training.
PURPOSE: Aim of this study was to investigate effects of 1) regular back extensor strength training as opposed to balance training, and 2) the influence of the sequence of both training types on postural control, force, and muscle efficiency. METHODS: Twenty-six young, healthy subjects were investigated at baseline, 1 month and 2 months later. At each examination, subjects completed a posturographic, balance skill, and isometric maximum voluntary (MVC) back extension testing, including surface electromyographic (SEMG) recordings. After baseline evaluation, subjects were assigned to either daily strength training or balance training. After 1 month, the type of training was exchanged between groups. RESULTS: After 1 month, back extensor strengthening led to decreased postural stability on hard surface, whereas there were no change after balance skill training. Analysis of the low- and high-frequency components of the sway signal revealed that strength training increased control efforts as indicated by an increased high-frequency component in order to maintain postural stability and unchanged low-frequency component. Balance skill training, however, increased postural stability as indicated by a decreased low-frequency component. The control effort remained unchanged. After completing either sequence of training, all postural parameters remained unchanged in both groups. Muscular efficiency as measured by SEMG root mean square during a standardized motor skill task revealed improved muscle economy regardless of the type of training. Back extension torque improved in both groups. CONCLUSION: To avoid reduction of postural stability in rehabilitation processes, we recommend to include antagonist muscles in a comprehensive strength training regime or balance skill training.