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.

Theoretical Expression of the Balance Function during Galvanic Vestibular Stimulation in Dual Space

“…The nonlinear property of SDEs is important although the concept of simple muscle stiffness control during quiet standing has been accepted for a long time [16,17]. However, the linear model [8][9][10] has been rejected by the experimental results of the relationship between the body posture angle and the ankle torque [18,19], and the postural instability, which is called "microfall" [20].…”

Influence of Long-Lasting Balancing on Unstable Surface on Changes in Balance

“…A decrease in preferences of the ankle strategy in this movement plane can be caused by tiredness [14], which, in consequence, can result in deterioration in stability. However, in some works, like in our research, it was observed that there was a more considerable increase in sways after an effort in the frontal plane than in the sagittal one.…”

“…In a standing position, in order to keep or recover balance it is possible to apply two strategies depending on the degree of its disturbance: an ankle or a hip joint [12][13][14]. One strategy refers to a minor balance distur bance and it is initiated by a contraction of ankle musc les.…”

“…One strategy refers to a minor balance distur bance and it is initiated by a contraction of ankle musc les. The other one refers to bigger disturbances and it is initiated by an activity of thigh and trunk muscles, and then moves downwards to other leg muscles [14][15][16].…”

Numerical simulation for Human Quiet Standing System

“…A large numbers of publication work [1][2][3][4] at the equilibrium stability of upright standing were based on the simple biomechanical model of the human body as single inverted pendulum. The multi-joint properties of the body were rarely taken into account in the previous studies.…”