VISUAL TARGETING DURING THE LONG JUMP APPROACH OF MALE BELOW-KNEE AMPUTEE PARALYMPIC ATHLETES
AbstractINTRODUCTION Previous research of visual control during the long jump suggests that visual control is not implemented until late in the approach phase, allowing the athlete to first concentrate on running velocity then on accurately hitting the toe-board. As it is known that performers modulate tirne-to-contact (tc) to target an object, it was hypothesized that male, below-knee amputee long jumpers do use visual perception to modulate tc during the entire approach The jumps for 10 male, below-knee athletes who successfully completed 3 jumps during competition in the 19% Paralympic Games were analyzed. They were videotaped (60 Hz) using a panning technique. The toe of the touchdown foot was digitized 3 times for each step of the approach phase. The means and SDs for each step, were generated across trials for each athlete for toe-position (ToeP), tc, and velocity (v). RESULTS AND DISCUSSION The mean tc pattern were linear or slightly curvlinear in a convex direction. As this pattern was a single mathematical function, e.g., linear, it suggests that the participants were able to use a single estimate for tc throughout the entire approach phase. This supports Lee and Thomson's (1982) statement that long jumpers regulate the time gap and not the distance between the jumper and the board. %o different SD tc patterns were demonstrated among the participants. SD tc Pattern 1 (Figure 1). which was exhibited by all but the top 3 jumpers, indicated that the variability for tc remained the same for all steps of the approach phase. As the SD to values for Pattern 1 were fairly constant, but the SD ToeP showed no consistent pattern, visual control must have been used during the entire approach phase. Because the better jumpers had lower SD tc values for the last steps of the approach, perhaps they did not choose to modulate tc to the same degree during the initial part of the approach phase as the lesser skilled jumpers. Cues related to velocity and some form of distance information have been shown to be useful in estimating tc . The correlations between tc and ToeP (r > 0.90) and v (0.25 - 0.74) could suggest that some form of distance but not v. information, was useful in assessing tc. REFERENCES Lee, D., et al., (1982). JEP: HPP, 8,428-459. Hay, J.G. (1988). Int. J. S. B., 4, 114-29. Berg, W.P., et al. (1995). J. A. B.,11, 142-62. 4. Laurent, M. (1991).
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