Biomechanical analysis of volleyball overhead pass.

In volleyball, the overhead pass is an important skill for passing a ball and making a set to attackers. In the present study, we analysed the overhead pass motion and involved muscle activity with special attention to the stretch-shortening cycle (SSC). Electromyogram was recorded from the wrist and elbow joint flexors and extensors. The movement period when the ball touched the hand was divided into the pull and push phases with the moment when the ball was at the lowest position. In the pull phase, although the wrists were extended, the activity of wrist flexor muscle was higher than the extensor muscle in both skilled and unskilled groups. And the activity in the wrist flexor muscle in the pull phase was higher in the skilled participants than that of the unskilled participants. Thus, the skilled participants pushed the ball by utilising the SSC of the wrist, while the unskilled participants did this in a less degree. In addition, the kinetic chain was observed from elbow to wrist in the skilled participants. We conclude that it is important for an overhead pass that the wrist flexor muscles accumulate elastic energy during the pull phase which is then released in the push phase.

Glucosamine-containing supplement improves locomotor functions in subjects with knee pain - a pilot study of gait analysis.

BACKGROUND: Previously, we demonstrated that glucosamine-containing supplementation was effective for improving locomotor functions, especially walking speed. However, the biomechanical mechanism of efficacy has not been elucidated. This study aimed to address this challenge in subjects with knee pain, using a motion capture system. METHODS: An open label study was conducted in 30 Japanese subjects with knee pain. The subjects were administered a daily supplement containing 1,200 mg of glucosamine hydrochloride, 60 mg of chondroitin sulfate, 45 mg of type II collagen peptides, 90 mg of quercetin glycosides, 10 mg of imidazole peptides, 1 mg of proteoglycan, and 5 µg of vitamin D (GCQID). The intervention continued for 16 weeks. Efficacy for locomotor functions involving the knee joint was evaluated mainly using the Japanese Knee Osteoarthritis Measure (JKOM) and the 5-question Geriatric Locomotive Function Scale (GLFS-5). To examine the biomechanical mechanism of efficacy for locomotor functions, motions of subjects in a normal walking state were captured. Gait analysis was conducted and efficacy for gait parameters such as normal walking speed, stride length, cadence, and angle of soles was evaluated. RESULTS: GCQID significantly improved total scores on the JKOM and GLFS-5. In gait analysis, normal walking speed, stride length, and angle of soles at the end of the stance phase were all significantly increased, but cadence did not change significantly during the intervention period. There were significant intercorrelations of changes in normal walking speed, stride length, and angle of soles at the end of the stance phase, and between changes in stride length and total JKOM score. CONCLUSION: A GCQID supplement may increase walking speed through increased stride length and angle of kicking from the ground during steps, which might be mainly associated with alleviated knee pain.