title: Ankle muscle stiffness in the control of balance during quiet standing.
abstract: This research presents new data and reanalyzed information to refute the criticisms of our model of stiffness control during quiet standing. A re-review of their references to biomechanical research on muscle ankle stiffness confirmed muscle stiffness estimates of the ankle series elastic elements that agreed closely with our estimates. A new technique is presented that directly estimates the muscle stiffness from the ankle moment (N. m) and sway angle (deg). The linear regression of 10 subjects standing quietly for 10 s estimated the stiffness (N x m/deg) to be safely above the gravitational spring. The R(2) scores for this linear regression averaged 0.92, confirming how closely the model approached a perfect spring that would have an R(2) = 1. These results confirm our model of a simple muscle stiffness control and refutes the criticisms.
authors.affiliation: Department of Kinesiology, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
authors.forename: D A
authors.initials: DA
authors.lastname: Winter
authors.forename: A E
authors.initials: AE
authors.lastname: Patla
authors.forename: S
authors.initials: S
authors.lastname: Rietdyk
authors.forename: M G
authors.initials: MG
authors.lastname: Ishac
mesh_terms: D000328:Adult; D000843:Ankle Joint / Q000502:physiology*; D004548:Elasticity; D006801:Humans; D016014:Linear Models; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D004856:Postural Balance / Q000502:physiology*