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Gait acts as a gate for reflexes from the foot
J Duysens1, C M Bastiaanse, B C M Smits-Engelsman
1Department of Medical Physics and Biophysics, University of Nijmegen, Geert Grooteplein 21, 6525 EZ Nijmegen, The Netherlands. j.duysens@science.ru.nl
Canadian Journal of Physiology and Pharmacology
|November 4, 2004
Summary
Phase-dependent reflex reversal in the tibialis anterior (TA) muscle was investigated using a split-belt treadmill. New findings show a TA suppressive pathway remains open during most of the stance phase, impacting ankle plantar flexor loading.
Area of Science:
- Neuroscience
- Biomechanics
- Human Gait Analysis
Background:
- Human gait involves phase-dependent reflex reversal, where electrical stimulation of the foot causes different responses in the tibialis anterior (TA) muscle depending on the gait phase.
- Previously, reflex reversal in TA was primarily studied during the swing phase due to the muscle's typical silence during stance, limiting understanding of its behavior during this crucial phase.
Purpose of the Study:
- To investigate the reflex reversal phenomenon in the tibialis anterior (TA) muscle during the stance phase of human gait.
- To explore the functional implications of TA reflex activity during stance, particularly in stabilizing the body and influencing ankle joint mechanics.
Main Methods:
- Subjects walked on a split-belt treadmill, inducing a limping gait pattern with increased TA activity during the stance phase of the slower leg.
- Electrical stimulation of the sural cutaneous nerve at the ankle was applied during this altered gait.
- Changes in TA muscle activity, specifically suppressive responses, were recorded and analyzed.
Main Results:
- Walking on a split-belt treadmill successfully induced sustained TA activity throughout most of the stance phase in most subjects.
- Electrical stimulation during the stance phase elicited suppressive responses in the TA muscle in a significant portion of subjects, particularly on the slow leg.
- These findings indicate that the neural pathway for TA suppression is active during the stance phase.
Conclusions:
- A suppressive pathway for the tibialis anterior (TA) muscle remains open during most of the stance phase in the majority of individuals.
- This TA suppression during stance may contribute to stabilizing the body and potentially increases the loading of ankle plantar flexors during the stance phase.