The reflexive control of knee stability during movement
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Date
2023-08-22
Authors
Kocer, Muhammet Berkan
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Abstract
Stimulation of the common peroneal nerve (CPN) excites quadriceps (Q) motoneurons, and it is
called the CPQ reflex. It has been suggested that the CPQ reflex assists in ground reaction force
(GRF) generation during walking when conditions require that, for example, at most commonly
used walking speeds or on an incline. This reflex is evoked by neurons in a spinal pathway
relaying sensory input from muscle afferents and descending locomotor commands. The CPQ
reflex pathway is thought to coordinate sensory input with ongoing motor activity. The aim here
was to evaluate the effects of the walking speed of the stimulated leg on the CPQ reflex. The
hypothesis that increased speed on one side will reduce the CPQ was tested. Neurologically
intact, generally healthy participants (n=12) in the 20-48 years old age range were evaluated
under different treadmill walking conditions: both legs walking at the same speed (BLW) or legs
walking with different speeds at a ratio 1 to 1.25 (R1.25), 1 to 1.5 (R1.5) and 1 to 2 (R2) so that
the right (R) belt speed was increased, and the left belt was kept constant. EMG responses in
lower leg muscles were compared in steps with and without stimulation of the CPN at an optimal
window after the R heel strike. Our result showed that as speed increased on the R side, the size
of the R CPQ reflex showed a tendency to decrease but no significant changes were found, likely
due to our sample size (n=5). To understand the factors that may influence the CPQ reflex, the
effect of walking speed under the stimulated side on ground reaction forces (GRFs), the stance
and swing time and the left-right asymmetry were also examined. Increasing speed amplified the
peaks of the anterior-posterior and vertical components of GRFs. We also found that R CPN
stimulation altered the left-right asymmetry of the propulsive peak of the GRFs. The findings of
this study are important for a better understanding of the CPQ reflex and for using CPN
stimulation in clinical settings to improve knee stability during walking.
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Keywords
CPQ, GRFs, Motor Control, CPN