The stretch reflex and H-reflex of the human soleus muscle during walking.
Due to the complexity of applying a well-defined stretch during human walking, most of our knowledge about the short latency stretch reflex modulation in humans is based on H-reflex studies. To illuminate the difference between the two methodologies, both types of reflexes were evoked in the same subjects, same experiment. Stretch reflexes were evoked via a stretch device capable of evoking stretch reflexes of the human soleus muscles during walking. H-reflexes were elicited by an electrical stimulation of the tibial nerve at the popliteal fossa at the knee. A significantly different modulation of the two reflexes was found in the late stance where the stretch reflex decreased in relation to the H-reflex. This was consistent with the unloading of the muscle spindles during the push-off in the late stance, suggesting a complex alpha-gamma coactivation, if any, at this time of the step. The soleus stretch reflex and H-reflex were compared during the stance phase of walking and sitting at matched soleus activity. No difference was found in the amplitude of the stretch reflex. However, there was a significant decrease of the H-reflex during the stance phase of walking, consistent with a task-specific presynaptic mediated reflex control. It is proposed that the short latency stretch reflex during walking is not sensitive to such a presynaptic inhibition.
Andersen
J B
JB
Center for Sensory-Motor Interaction, Dept. Med. Inform. & Image Analysis, Aalborg Univ., Fredrik Bajers Vej 7D-3, DK-9220 Aalborg, Denmark.
Sinkjaer
T
T
D000328:Adult; D004576:Electromyography; D005260:Female; D006181:H-Reflex / Q000502:physiology*; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000294:innervation*; D012026:Reflex, Stretch / Q000502:physiology*; D013997:Time Factors; D016138:Walking / Q000502:physiology*