Influence of block angle and diver stance on power production and takeoff velocity in swim starting.

Abstract

This research examined three different diving stances during the competitive grab start of swimming--that of the standard position, called the Toes-Over position, the Toes-Back position where the swimmers were not permitted to curl their toes over the edge of the $-$10 degree inclined starting block and the Level position where the platform was levelled. A starting position was being sought which would increase a swimmer's projection angle from the blocks and thus flight time before entry. Eight female swimmers were filmed using a stationary cinecamera while reaction forces were collected, simultaneously, by a force platform mounted on the starting block. Net forces and moments of force at the three leg joints were calculated using inverse dynamics (Winter, 1979). The powers produced by these net moments were then computed to determine which muscle groups contributed to the work done during the start. Based on the results of this study there were no significant differences in the performances of female swimmers using the grab start technique in terms of takeoff velocity, takeoff angle or horizontal distance for the dive when starting from a level surface or $-$10 degree inclined surface. The hip extensor muscles provided the greatest amount of power during the propulsive (thrust) phase of the swim start.