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Plantar flexor stretch reflex responses to whole body loading/unloading during human walking
Author(s) -
Grey Michael J.,
Van Doornik Johan,
Sinkjær Thomas
Publication year - 2002
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1046/j.1460-9568.2002.02250.x
Subject(s) - ankle , reflex , biceps , stretch reflex , physical medicine and rehabilitation , treadmill , anatomy , medicine , weight bearing , electromyography , physical therapy , anesthesia , surgery
Numerous animal and human studies have shown that afferent information from the periphery contributes to the control of walking. In particular, recent studies have consistently shown that load receptor input is an important element of the locomotion control mechanism. The objective of this study was to investigate the contribution of load receptor feedback to the compensatory stretch reflex response. We examined the contribution of load receptor feedback to the magnitude of the short and medium latency components of the ankle plantar flexor stretch reflex responses following an unexpected dorsiflexion perturbation during human walking. Three body load conditions were investigated: normal body load, a 30% increase in body load, and a 30% decrease in body load. Healthy subjects walked on a treadmill at ∼ 3.6 km/h with the left ankle attached to a portable stretching device. Dorsiflexion perturbations (8°; 350–425 °/s) were generated during the late stance phase of gate (∼ 400 ms following heel contact). Electromyographic activity was recorded from the soleus, tibialis anterior, medial gastrocnemius, rectus femoris, and biceps femoris muscles using bipolar surface electrodes. Stretch reflex responses were observed in the soleus and gastrocnemius muscles for all of the body load conditions; however, increasing or decreasing the body load did not affect the timing and magnitude of the responses. This study provides evidence that load receptor input does not contribute strongly to the corrective response of the stretch reflex in the plantar flexor muscles during walking.