Figure 1. Male subject (left) and female subject (right) are shown with joint markers placed on the lateral malleolus, lateral epicondyle of the femur, the greater trochanter, and the acromion process.
The subjects for this study were a set of three year old (46 mos.) male and female twins. The male subject weighed 142.4 N and stood 0.97 meters. He was bare footed and wore white underwear. The female subject weighed 151.3 N and stood 0.98 meters. She wore pink underwear for the experiment and also had bare feet. Any previous movement experience was similar for both subjects. Four joint markers were placed on the subjects at the lateral malleolus, lateral epicondyle of the femur, the greater trochanter, and the acromion process.
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Figure 1. Male subject (left) and female subject (right) are shown with joint markers placed on the lateral malleolus, lateral epicondyle of the femur, the greater trochanter, and the acromion process. | |
A Sony 8mm video camera with a 30 frames per second rate was used to capture the data for this study. The camera was placed perpendicular to the sagittal plane of the subjects. Three large utility light were used to provide adequate lighting for video recording. The subjects were instructed to complete a long jump, jumping as far as they could in the longitudinal direction. A number of trials were completed and recorded, and each subject's longest jump was analyzed. Length of jump was the main criteria used to select trials for analysis.
The videotaped images were digitized at 30 frames per second using FusionRecorder on Macintosh computers in the New Media Center at the University of Michigan. The digital video files were trimmed using MoviePlayer so that the data files contained only the frames between the beginning of knee flexion and the completion of the jump at maximum knee flexion during landing. A custom utility (QT->PICT) was used to convert the Quicktime movie files into a series of individual frame files in PICT format for use with the Motion Plus software. Joint markers on the lateral malleolus, lateral epicondyle of the femur, the greater trochanter, and the acromion process were digitized using Motion Capture. Joint marker coordinate data were exported in spread sheet format to Excel for biomechanical analysis using Motion Analyse.