Figure 1. Joint markers in the bicep curl with the heavy weight (left) and the bicep curl with the light weight (right). Joint markers were placed on the shoulder, elbow, hip, weight, knee and ankle joints.
The subject used in this research was a 20 year old female, 1.65 meters tall, and weighed 690 N. The subject was dressed in black lycra shorts, a black sleeveless t-shirt and gym shoes. The subject engages in this movement (bicep curls) twice a week as part of her training schedule. The joint markers were placed on the glenohumeral joint, lateral aspect of humeroradial joint, greater trochanter, bar of the weight used, lateral epicondyle of femur and lateral malleolus.
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Figure 1. Joint markers in the bicep curl with the heavy weight (left) and the bicep curl with the light weight (right). Joint markers were placed on the shoulder, elbow, hip, weight, knee and ankle joints. | |
The movement was taped with a Sony Hi 8 camera at thirty frames per second in a racquetball court in the basement of the Central Campus Recreation Building. An accessory camera light was used to illuminate the subject's movement. The camera was situated in the sagittal plane 6.5 meters away from the subject. The subject was instructed to perform a bicep curl from the standing position using a 30 pound and 45 pound weight 4 times for both weights. The movement begins with the elbow in full extension, continues to full flexion and ends in full extension. We selected trials that had the greatest postural differences between light and heavy weights.
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 between the start and end of the movements. 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. The shoulder, elbow, hip, weight, knee and ankle were digitized using Motion Capture. Joint marker coordinate data were exported in spreadsheet format to Excel for biomechanical analysis using MotionAnalyse.