Reflex ankle stiffness is inversely correlated with natural body sway.

We aimed to determine whether effective ankle stiffness (EAS), measured during slow unperceived perturbations of stance, is related to natural anterior-posterior body sway. Because the perturbations are not perceived, any neural component of the response to perturbation is assumed to be "reflex", in the broad sense of an involuntary response to a stimulus. Subjects stood on a force platform for three 10-min trials.

The effect of foot wedging on electromyographic activity in the erector spinae and gluteus medius muscles during walking.

The use of foot orthoses for treatment of low back pain (LBP) has received some attention in the literature, mainly from a clinical or theoretical perspective. It has been proposed that this treatment alleviates pain by altering muscle activity in the area of the low back but there is no direct evidence of such an effect. The objective of this study was to determine the effects of different types of foot wedging on the bilateral surface electromyographic activity of erector spinae (ErSp) (L3 level) and gluteus medius (GlMed) of 13 participants without LBP.

Ankle reflex stiffness during unperceived perturbation of standing in elderly subjects.

Postural reflex activity during unperceived perturbation of standing was investigated in 38 elderly subjects (70-96 years old) and 10 younger adults (19-48 years old), and it was related in the elderly group to a history of unexplained falling in the 12 months prior to testing. Ankle torque (T) and ankle angle (A) were recorded during unperceived forward pulls to obtain the ankle stiffness (DeltaT/DeltaA), providing a measure of postural reflex activity at the ankle. Elderly nonfallers and younger adults had similar ranges of normalized ankle reflex stiffness.