Figure 1. Joint markers in the running motion of a male (left) and female subject (right). The greater trochanters, lateral epicondyles, and lateral malleoli of both lower limbs were marked.
The first subject used in this study was a twenty-one year old male. He was 1.91 meters in height and weighed 92.9 kg. The second subject was a twenty-year-old female. She was 1.83 meters tall and weighed 70.5 kg. Both subjects wore tight clothing and socks so that the movement of their lower limbs and the exact moment of footstrike could be determined. Neither subject had competitive running experience to ensure that the selective effects of competitive success were not a confounding variable. The joint markers, styrofoam balls, were placed on the greater trochanters of both hips, the lateral epicondyles of both knees and the lateral malleoli of both ankles.
|
|
|
|
Figure 1. Joint markers in the running motion of a male (left) and female subject (right). The greater trochanters, lateral epicondyles, and lateral malleoli of both lower limbs were marked. | |
Data collection was initialized during a videotaping session. A Sony Hi-8 video camera, a high voltage background light (a tripod for both), and a Hi-8 video cassette were used to record the movements which were being compared. The next important aspect was the data collection environment. Video taping took place in the basement of the University of Michigan Intramural Sports Building. The lighting in the basement was very dim, so the use of a high voltage light was essential to ensure the quality of the taping. The subjects performed their running action on a stationary, electrical treadmill. Due to background activity, a blue mat was used as the background scene. The camera and lighting was set up behind the subjects for later so that the mechanics of the front of the treadmill did not interfere with a complete view of the gait cycle. The subjects were instructed to wear dark, tight fitting clothing (to contrast with white joint markers), to wear no shoes and to run for one minute with the treadmill set at a speed of 4.2 miles/hr.
The videotaped images were digitized at 30 frames/s 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 of one gait cycle. 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. Our 3-dimensional like joint markers were digitized using Motion Capture. Joint marker coordinate data were exported in spreadsheet format to Excel for biomechanical analysis using MotionAnalyse.