Gait & posture
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Comparative Study
Foot sole skin vibration perceptual thresholds are elevated in a standing posture compared to sitting.
Foot sole sensitivity is commonly assessed while individuals are seated or prone; however the primary role of foot sole cutaneous feedback is for the control of upright stance and gait. The aim of this study was to compare vibration perceptual thresholds across the foot sole between sitting and standing postures. Vibration perceptual thresholds were measured in sitting and standing postures in 18 healthy participants (8 male) using a custom vibration device. ⋯ In addition, threshold differences between the heels and metatarsals for lower frequency vibratory stimuli were more pronounced while standing, with higher thresholds observed at the heels. Our results demonstrate that standing significantly alters sensitivity across the foot sole. Therefore, conducting perceptual tests at the foot sole during stance could potentially provide more direct information about the ability of cutaneous afferents to signal tactile information in a state where this feedback can contribute to postural control.
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Despite the strong relationship between freezing of gait (FOG) and turning in Parkinson's disease (PD), few studies have addressed specific postural characteristics during turning that might contribute to freezing. ⋯ Our results revealed no subgroup differences in COM behavior during uninterrupted turning. However, we found a reduced medial deviation, a forward COM shift and a decreased step width in freezers just before FOG episodes. These abnormalities may play a causal role, as they could hamper stability and fluent weight shifting necessary for continued stepping during turning.