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Abstract
The investigation of force attenuation and performance mechanisms during landings help identify performance strategies used during the activity. The purpose of the study was to evaluate the effects of height (3), distance (3) and landing technique (3) on impact forces. In addition, the effects of selected joint kinematics on landing technique were evaluated.
Three semi-skilled male volunteers served as subjects. The experimental set-up consisted of a force platform interfaced to a laboratory computer, a high speed camera, and an adjustable height jumping tower. Subjects were filmed while performing three right foot landings on the force platform for each combination of height, distance and technique for a total of 81 trials.
Temporal and kinetic data describing the maximum impact force value(s) and joint position and velocity data were used in the analysis.
A single-subject analysis was employed for all statistical procedures. First and second maximum vertical forces and times of occurrence were analyzed using a three-way ANOVA technique. Regression models were used to identify critical performance factors associated with the forces. A regression model was also computed to identify the most important kinematic variables related to technique.
First and second maximum force ANOVA results indicated significant (p = 0.05) height and distance main effects for S1 and S2, while S3 exhibited significant interactions. Three unique performance models were apparent for braking force and times of occurrence for these events.
The regression analyses using the first maximum force as the dependent variable explained 57.6, 82.9 and 40.5% of the variance for the three subjects respectively, using the independent variables of height and distance. The incorporation of technique as an independent variable improved the predictions to 81.7, 83.3 and 40.5%. Prediction of the second maximum force resulted in 31.9, 19.7, and 10.1% and 72.8, 60.4, and 59.1% explained variance for the models, respectively. Prediction of landing technique from kinematic variables produced models accounting for 13.1, 74.0 and 63.1% of the variance for the three subjects.
Results of the statistical analyses suggest that different performance strategies were being used by each subject to accommodate to the demands imposed by the various landings investigated.
