Postural control at different anatomical levels: dependence upon sport practice
AbstractControl of equilibrium in upright posture is a multifactorial phenomenon influenced by the sensory modalities involved or by the characteristics of the environment. Or of the subjects. We have to specify how the practice of sports, especial1y judo or dance, could influence the role of the sensory information and t he postural strategies used. Practicers of Judo and dancers need to tram to control their equilibrium, in order for the judoka to maintain their own standing position while attempting to throw their opponents to the ground, or for the dancers to make the movements of the desired shape. Is this experience and skill generalized to the control of static equilibrium and which sensory aspects are trained the most (Crbmieux, Mesure, 1990, 1992), and does it change the postural strategies of the subjects? To answer these questions, an experiment was carried out with 60 young healthy adults: 2 groups of novice men and women, one group of men and one of women expert in Judo (black belt) and one group of women expert in classic dance ( 5years of practice). The subjects were tested in a sharpened Romberg position on either a hard or a soft surface within a vertical cylinder with vertical black and white stripes. Three type of illumination were used: normal or 2 Hz stroboscopic light, and darkness. Accelerometers were used to measure the subject's lateral (head and hips) or antero-posterior (ankles) body sway. A frequency power spectrum analysis shows a better static control in the expert men and women than in the beginners; but this improvement is not due to an aspecific increase in the use of visual, vestibular or proprioceptive cues for the three expert groups; rather it depends on the sport and sex of the subjects. They did not choose the same information for their own control. A study of the correlations between performances at the different anatomical levels show that the relation between motion of the different body levels are not the same for the five groups. To study the effect of sex and sport on this relative movements, we use .a new statistical determination of postural strategies (Amblard et al., 1992a. b) between two anatomical levels, by mean of a method based on the crosscorrelation functions between two simultaneous time series of accelerometric measurements. Results show that men and women, a as well as novices and experts have not the same relative body movements.
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