Functioning of peripheral Ia pathways in leg muscles of newly walking toddlers.

•As walking experience/skill increased, integrity of peripheral Ia pathways showed gradual improvement.•The integrity of the T-reflex tended to be strengthened in QAD and GS, but TA seemed to require more walking practice to be improved and stabilized.•The distribution of the pattern shifted from multiple types of responses toward a single type of reflex response in all tested muscles.•The function of presynaptic inhibition and polysynaptic pathways tended to remain unstable even with 3 months of walking experiences.