This study compared shoulder impingement behaviors between two commonly used wheelchair propulsion techniques, the conventional and the competitive techniques. High incidence of shoulder pain was found in wheelchair athletes. Wheelchair athletes commonly used two techniques in manual wheelchair propulsion, that is, the conventional and the competitive. Shoulder pain involves abnormal stress acts on the subacromial space in which many soft tissues exist. Understanding shoulder impingement behavior associated with different propulsion techniques may provide important information in shoulder pain prevention. Ten wheelchair users voluntarily participated in this study. In order to understand shoulder kinematics behaviors, the Zebris motion analysis system was used to collect marker coordinates. A biomechanical model was developed for describing shoulder three-dimensional motion behavior. The t-test was used to examine the difference among the investigated parameters in both the conventional and the competitive techniques. The results showed that the biomechanical model in the present study was valid as supported by the root-mean-square value less than 6.50 and the Pearson correlation coefficient of 0.9. In shoulder kinematics behaviors, the conventional and the competitive techniques had similar push time (60%) and recovery time (40%) (p>.05). Compared with the conventional technique, the competitive technique had a larger shoulder-elbow working area occurrence in the efficient zone (t=4.67, p<.05) and had more joint excursion in the impingement zone (t=4.87, p<.05). Based on the present study, we believed the propulsion technique could be a pre-determined factor in causing shoulder impingement injury. Competitive propulsion caused an athlete's shoulder to be largely involved in position of abduction, flexion and internal rotation. This combined shoulder position may produce abnormal stress acting on the soft tissue beneath the subacromial space. In order to prevent shoulder pain in wheelchair athletes, coaches and trainers must realize the differences of mechanical stress acting on the shoulder tissue in both the conventional and the competitive propulsion techniques.
This study compared shoulder impingement behaviors between two commonly used wheelchair propulsion techniques, the conventional and the competitive techniques. High incidence of shoulder pain was found in wheelchair athletes. Wheelchair athletes commonly used two techniques in manual wheelchair propulsion, that is, the conventional and the competitive. Shoulder pain involves abnormal stress acts on the subacromial space in which many soft tissues exist. Understanding shoulder impingement behavior associated with different propulsion techniques may provide important information in shoulder pain prevention. Ten wheelchair users voluntarily participated in this study. In order to understand shoulder kinematics behaviors, the Zebris motion analysis system was used to collect marker coordinates. A biomechanical model was developed for describing shoulder three-dimensional motion behavior. The t-test was used to examine the difference among the investigated parameters in both the conventional and the competitive techniques. The results showed that the biomechanical model in the present study was valid as supported by the root-mean-square value less than 6.50 and the Pearson correlation coefficient of 0.9. In shoulder kinematics behaviors, the conventional and the competitive techniques had similar push time (60%) and recovery time (40%) (p>.05). Compared with the conventional technique, the competitive technique had a larger shoulder-elbow working area occurrence in the efficient zone (t=4.67, p<.05) and had more joint excursion in the impingement zone (t=4.87, p<.05). Based on the present study, we believed the propulsion technique could be a pre-determined factor in causing shoulder impingement injury. Competitive propulsion caused an athlete's shoulder to be largely involved in position of abduction, flexion and internal rotation. This combined shoulder position may produce abnormal stress acting on the soft tissue beneath the subacromial space. In order to prevent shoulder pain in wheelchair athletes, coaches and trainers must realize the differences of mechanical stress acting on the shoulder tissue in both the conventional and the competitive propulsion techniques.