The pattern of modulation of short latency reflex linking the pretibial muscles to the knee extensors during gait in human

Objective: To find out pattern of modulation of heteronymous reflex linking the pretibial muscles to quadriceps motoneurones in normal subjects during treadmill walking. Methodology: A non-randomized quasi-experimental study was performed in ten cases in Shahid Beheshti University (MC) Tehran, Iran, from September 2006 to August 2007. The reflex was elicited by applying stimuli of three time's motor threshold in tibialis anterior to common peroneal nerve at several instants of gait cycle. Surface EMGs from tibialis anterior, vastus medialis and rectus femoris of the right leg was used to measure the intensity of the muscular activity and the magnitude of the reflex. The data were analysed by Pearson test for the strength of their correlation. Results: The reflex showed a significant correlation with the intensity of contraction in quadriceps especially during the early stance phase. The correlation was poor during transition period from stance to swing where rectus femoris showed a small peak of activity. The peak of activity in tibialis anterior was on average 69ñ21ms preceded that of quadriceps. Conclusions: This precedence of activity in tibialis anterior and the strong presence of the reflex during the early stance phase may indicate a positive feed-forward effect from ankle flexor afferents to quadriceps