Withdrawal reflexes examined during human gait by ground reaction forces: site and gait phase dependency

Abstract

The objective of this study was to investigate the modulation of the nociceptive withdrawal reflex during gait measured using Force Sensitive Resistors (FSR). Electrical stimulation was delivered to four locations on the sole of the foot at three different time points between heel-off and toe-off. Peak force changes were measured by FSRs attached to the big toe, distal to the first and fourth metatarsophalangeal joints, and the medial process of the calcaneus on both feet. Force changes were assessed in five gait sub-phases. The painful stimulation led to increased ipsilateral unloading (10 +/- 1 N) and contralateral loading (12 +/- 1 N), which were dependent on stimulation site and phase. In contrast, the hallux of the ipsilateral foot plantar flexed, thus facilitating the push-off. The highest degree of plantar flexion (23 +/- 10 N; range, 8-44 N) was seen in the second double support phase following the stimulation. Site and phase modulation of the reflex were detected in the force signals from all selected anatomical landmarks. In the kinematic responses, both site and phase modulation were observed. For stimulations near toe-off, withdrawal was primarily accomplished by ankle dorsiflexion, while the strategy for stimulations at heel-off was flexion of the knee and hip joints.

Computer-aided analysis of gait rhythm fluctuations in amyotrophic lateral sclerosis

“…Previous studies [4,8,9,11,14,15,21] demonstrated that computeraided analysis of gait patterns could help the neurologist better understand the mechanism of motor control in the human body, and is also useful for monitoring of progressive neurological diseases. The research group led by Akay, Tamura, and Fujimoto [1,2,27,28] applied the wavelet-based fractal analysis and time-frequency matching pursuit algorithm to acceleration signals recorded during climbing stairs and walking along a corridor, in order to study the gait patterns related to neurodegenerative diseases.…”

Investigation of foot plantar pressure: experimental and numerical analysis

“…The Pedar Ò system (Novel GmbH, Munich, Germany) is one of the systems most commonly used for in-shoe-pressure measurement. In the literature, several studies confirm the accuracy and repeatability in plantar pressure measurement achieved using this system [2][3][4][5][6]. This system was used to investigate plantar pressure distribution in different conditions, for example, between man and woman [7], between right and left foot [8], between young and old people [9] and with regard to subjects walking barefoot or in comfortable shoes [10,11].…”

Stimulation site and phase modulation of the withdrawal reflex during gait initiation

“…The stimulation was delivered through selfadhesive electrodes (AMBU Neuroline 700, Denmark). A reference electrode (7 Â 10-cm electrode, Pals, Axelgaard Ltd., USA) was placed on the dorsal aspect of the foot (Emborg et al, 2009). Each stimulus consisted of a constant current pulse burst of five individual 1-ms pulses delivered at 200 Hz.…”