Effect of vision and stance width on human body motion when standing: implications for afferent control of lateral sway.

Abstract

SUMMARY1. Measurements of human upright body movements in three dimensions have been made on thirty-five male subjects attempting to stand still with various stance widths and with eyes closed or open. Body motion was inferred from movements of eight markers fixed to specific sites on the body from the shoulders to the ankles. Motion of these markers was recorded together with motion of the point of application of the resultant of the ground reaction forces (centre of pressure).2. The speed of the body (average from eight sites) was increased by closing the eyes or narrowing the stance width and there was an interaction between these two factors such that vision reduced body speed more effectively when the feet were closer together. Similar relationships were found for components of velocity both in the frontal and sagittal planes although stance width exerted a much greater influence on the lateral velocity component.3. Fluctuations in position of the body were also increased by eye closure or narrowing of stance width. Again, the effect of stance width was more potent for lateral than for anteroposterior movements. In contrast to the velocity measurements, there was no interaction between vision and stance width.4. There was a progressive increase in the amplitude of position and velocity fluctuations from markers placed higher on the body. The fluctuations in the position of the centre of pressure were similar in magnitude to those of the markers placed near the hip. The fluctuations in velocity of centre of pressure, however, were greater than of any site on the body.

Stabilometric parameters are affected by anthropometry and foot placement

“…Subject morphology together with joints and muscle function have been identified, in a systems approach, as the main biomechanical factors (BF) involved in balance control [10]. Body size and foot placement are known to influence postural stability [11][12][13][14][15] but their impact on stabilometric parameters has not been extensively explored yet.…”

Human body‐segment tilts induced by galvanic stimulation: a vestibularly driven balance protection mechanism.

“…First, it increases the size of the base of support so that changes in the position of the body's centre of mass present less of a threat to balance. Second, the lower body structure becomes more stable in the frontal plane because hip joint muscles and proprioceptors are better able to co-operate with those of the ankle joints to control the structure (Day, Steiger, Thompson & Marsden, 1993). In addition to its influence on balance, stance width is also an interesting variable from the point of view of head motion.…”

Influence of prolonged wearing of unstable shoes on upright standing postural control

“…Indeed, the results of this study reveal that prolonged wearing of the unstable shoes led to a large effect in the increase of thigh antagonist co-activation. A transfer of postural control synergy for the thigh has been demonstrated in compensatory responses after a 8 weeks period of wearing unstable shoes (Sousa et al, 2014) and has been reported as more beneficial to optimise postural stability (Day et al, 1993;Horak et al, 1990;Kuo, 1993;Runge et al, 1999;Yang et al, 1990). This association is corroborated not only by the decrease of the most representative CoP displacement parameters and RM P-P, but also by decreased anterior-posterior TR RMS.…”