The effect of resistance strength training on different phases of reactive postural responses to upright-stance perturbation was assessed in elderly women. Perturbation to body balance was produced by fast arm movements aiming at lifting different loads in either certain or uncertain contexts. Results from center-of-pressure analysis showed that lifting a light load under uncertainty led to more body sway than under certainty. Resistance strength training led to short periods of body sway in the compensation phase and to decreased variability in the stabilization phase of postural responses. These results suggest that neuromuscular adaptation from resistance strength training benefits late phases of postural responses to perturbation of body balance in the elderly.
The authors are with the Dept. of Biodynamics of Human Movement, University of São Paulo, São Paulo, Brazil.