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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Individual differences in intrinsic ankle stiffness and their relationship to body sway and ankle torque

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Sakanaka, Tania E. [1, 2] ; Lakie, Martin [2] ; Reynolds, Raymond F. [2]
Total Authors: 3
[1] Univ Estadual Campinas, Fac Med Sci, Campinas, SP - Brazil
[2] Univ Birmingham, Sch Sport Exercise & Rehabil Sci, Birmingham, W Midlands - England
Total Affiliations: 2
Document type: Journal article
Source: PLoS One; v. 16, n. 1 JAN 22 2021.
Web of Science Citations: 1

When standing, intrinsic ankle stiffness is smaller when measured using large perturbations, when sway size is large, and when background torque is low. However, there is a large variation in individual intrinsic ankle stiffness. Here we determine if individual variation has consequences for postural control. We examined the relationship between ankle stiffness, ankle torque and body sway across different individuals. Ankle stiffness was estimated in 19 standing participants by measuring torque responses to small, brief perturbations. Perturbation sizes of 0.2 \& 0.9 degrees (both lasting 140 ms) measured short- and long-range stiffness respectively, while participants either stood quietly on a fixed platform or were imperceptibly tilted to reduce stability (0.1 Hz sinusoid; 0.2 \& 0.4 deg). The spontaneous body sway component (natural random relatively rapid postural adjustments) and background ankle torque were averaged from sections immediately before perturbations. The results show that, first, intrinsic ankle stiffness is positively associated with ankle torque, and that this relationship is stronger for long-range stiffness. Second, intrinsic ankle stiffness is negatively associated with body sway, but, in contrast to the relationship with torque, this relationship is stronger for short-range stiffness. We conclude that high short-range intrinsic ankle stiffness is associated with reduced spontaneous sway, although the causal relationship between these two parameters is unknown. These results suggest that, in normal quiet standing where sway is very small, the most important determinant of intrinsic ankle stiffness may be stillness. In less stable conditions, intrinsic ankle stiffness may be more dependent on ankle torque. (AU)

FAPESP's process: 18/16103-7 - Use of accelerometers integrated in microelectromechanical systems (MEMS) in identifying distinct patterns of movement in children with different cerebral palsy subtypes and assessing the effects of botulinum neurotoxin type A intervention
Grantee:Tania Emi Sakanaka
Support Opportunities: Scholarships in Brazil - Post-Doctoral