Regulation of gait in long jumping.

The way in which gait is regulated to meet the demands of the terrain was investigated by analyzing the movements of skilled long jumpers during their run-up to the takeoff board. The analysis revealed that the run-up consists of two phases: (a) an initial accelerative phase, ending about 6 m from the board, during which athletes attempt to produce a stereotyped stride pattern; and (b) a zeroing-in phase, during which they adjust their stride pattern to eliminate error that has accrued. Further analysis revealed that the athletes were regulating a single gait parameter—the vertical impulse, or lift, of their steps. During the stereotyped approach phase they tried to maintain a constant impulse, thereby keeping flight and swing-through time constant. During the zeroing-in phase, they adjusted their flight times (and hence their stride lengths) by regulating the impulse of their steps. The essence of their skill thus appears to lie in the precise adjustment of the impulse toward the end of the run-up. The nature of the visual information that might be used to make the adjustments is discussed.