Starting from standing; why step backwards?
At push-off, the mass centre of gravity of the body must be positioned in front of the foot to prevent a somersault. When starting a sprint from out the standing position the use of a step backwards is necessary for maximal acceleration. The aim of the present study was to quantify the positive contribution to push off from a backward step of the leg, which seems to be counterproductive. Ten subjects were instructed to sprint start in three different ways: (a) starting from the standing position just in front of the force platform on the subject's own initiative, (b) starting from the standing position on the force platform with no step backward allowed, and (c) starting out of the starting position with one leg in front of the force platform and the push-off leg on the force platform. A step backwards was observed in 95% of the starts from the standing position. The push-off force was highest in starting type (a), which had the shortest time to build up the push-off force. The results indicate a positive contribution to the force and power from a step backwards. We advocate developing a training program with special attention to the phenomenon step backwards.
Kraan
G A
GA
Department of Biomedical Physics and Technology, Faculty of Medicine and Allied, Health Sciences, Erasmus University Rotterdam, P.O. Box 1738 3000 DR, Rotterdam, Netherlands. vankruining@bnt.fgg.eur.nl
van Veen
J
J
Snijders
C J
CJ
Storm
J
J
D000328:Adult; D000843:Ankle Joint / Q000502:physiology; D006621:Hip Joint / Q000502:physiology; D006801:Humans; D007866:Leg / Q000502:physiology; D008297:Male; D009068:Movement / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D012420:Running / Q000502:physiology*; D013177:Sports / Q000502:physiology*