This study examined variability in kicking speed and spatial accuracy to test the impulse-variability theory prediction of an inverted-U function and the speed-accuracy trade-off. Twenty-eight 18- to 25-year-old adults kicked a playground ball at various percentages (50–100%) of their maximum speed at a wall target. Speed variability and spatial error were analyzed using repeated-measures ANOVA with built-in polynomial contrasts. Results indicated a significant inverse linear trajectory for speed variability (p < .001, η2= .345) where 50% and 60% maximum speed had significantly higher variability than the 100% condition. A significant quadratic fit was found for spatial error scores of mean radial error (p < .0001, η2 = .474) and subject-centroid radial error (p < .0001, η2 = .453). Findings suggest variability and accuracy of multijoint, ballistic skill performance may not follow the general principles of impulse-variability theory or the speed-accuracy trade-off.
Chappell is with the Los Angeles Angels Baseball Club, Jonestown, TX. Molina is with the Dept. of Health, Physical Education, and Recreation, Missouri Western State University, St. Joseph, MO. Stodden is with the Dept. of Physical Education and Athletic Training, University of South Carolina, Columbia, SC. McKibben is with the Dept. of Health, Exercise, and Sports Science, Lubbock, TX.