Computerized dynamic posturography in ballet dancers

Abstract

Balance is the ability to maintain an individual’s centre of mass over his or her base of support while standing. Ballet dancers have better balance than non-dancer control groups as they presented with better sensory-motor integrative skills when required to maintain a given posture for a longer period. To evaluate functional balance abilities, assessing individuals with above average balance abilities may provide valuable information about function. The balance of trained ballet dancers (N1) was investigated by comparing Sensory Organisaiton Test (SOT), Motor Control Test (MCT) and Limits of Stability (LOS) test results to matched non-trained individuals (N2). A quasi-experimental and two group design was used. Ten matched trained ballet dancers (N1) and 10 untrained individuals were included in the study. Trained ballet dancers (N1) had an average of 16.6 (± 4.24) years of experience, while non-trained individuals (N2) had none. No significant dufferences in demographic data was present between groups. Both groups reflected good overall balance and similar sensory organization. No differences in reflex latencies and weight symmetry of the left or right leg was present. Trained ballet dancers (N1) reflected higher response strength for medium forward translations (p.05) with the left leg, indicating poorer amplitude scaling in response to platform translations than those of non-trained individuals (N2). In non-trained individuals (N2), there was less variation in the response strength between legs. Research indicated that stretch reflex amplitude was attenuated as load stability was reduced. Co-contraction was also heightened as stability was reduced, but not enough to oppose the induced instability, probably due to feed-forward strategies instead of rapid involuntary feedback. Trained ballet dancers (N1) were able to extend further out of their Centre of Pressure (COP) than non-trained individual (N2) during forward (p<.05) and right forward (p<.05) movements. It was concluded that that for forward and right forward movements, ballet dancers used the feedback they received during the movements better than non-trained individuals (N2), resulting in a better awareness of where to go in space and how to reach that position after a subsequent attempt. This difference may be as a result of continuous training. Ballet training exercises can be used to rehabilitate individuals with impaired limits of stability. Further studies should be done on exactly which ballet training exercise results in increased limits of stability.