Center of gravity motions and ankle joint stiffness control in upright undisturbed stance modeled through a fractional Brownian motion framework.
The authors modeled the center of gravity vertical projection (CG(v)) and the difference, CP - CG(v), which, combined, constitute the center of pressure (CP) trajectory, as fractional Brownian motion in order to investigate their relative contributions and their spatiotemporal articulation. The results demonstrated that CG(v) and CP - CG(v) motions are both endowed in complementary fashion with strong stochastic and part-deterministic behaviors. In addition, if the temporal coordinates remain similar for all 3 trajectories by definition, the switch between the successive control mechanisms appears for shorter displacements for CP - CG(v) and CG(v) than for CP trajectories. Results deduced from both input (CG(v)) and muscular stiffness (CP - CG(v)) thus provide insight into the way the central nervous system regulates stance control and in particular how CG and CP - CG are controlled.
Rougier
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P
Sport and Motor Performance Laboratory, Joseph Fourier University, Grenoble, France. patrice.rougier@univ-savoie.fr
Caron
O
O
D000328:Adult; D000843:Ankle Joint; D005260:Female; D006112:Gravitation; D006801:Humans; D007537:Isometric Contraction; D008297:Male; D008875:Middle Aged; D004856:Postural Balance; D011187:Posture; D011601:Psychophysics; D016059:Range of Motion, Articular; D013269:Stochastic Processes; D016474:Weight-Bearing