Starting from standing; why step backwards?

At push-off the mass centre of gravity of the body must be positioned in fr ont of the foot to prevent a somersault. When starting a sprint from out th e standing position the use of a step backwards is necessary for maximal ac celeration. The aim of the present study was to quantify the positive contr ibution to push off From a backward step of the leg, which seems to be coun terproductive. Ten subjects were instructed to sprint start in three differ ent ways: (a) starting from the standing position just in front of the forc e platform on the subject's own initiative, (b) starting from the standing position on the force platform with no step backward allowed, and (c) start ing out of the starting position with one leg in front of the force platfor m 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 hi ghest in starting type (a), which had the shortest time to build up the pus h-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. (C) 2001 Elsevier Scie nce Ltd. All rights reserved.