Fast running tracks.
D000818:Animals; D001001:Anura; D001696:Biomechanical Phenomena; D006801:Humans; D008465:Mechanoreceptors / Q000502:physiology; D008954:Models, Biological; D009119:Muscle Contraction; D009132:Muscles / Q000502:physiology*; D012026:Reflex, Stretch; D012420:Running