博士 課程 早稲田大学 スポーツ科学
修士 課程 上海体育学院
複合領域 / 健康・スポーツ科学 / スポーツ科学
概要：The aims were to quantitatively describe the coordinated motions of the scapula and humerus during fully tethered front-crawl strokes and to test the hypothesis that scapular motion functions to reduce the risk of subacromial compression. An electromagnetic tracking device was used to record the kinematics of the thorax, humerus, and scapula on the dominant side in 17 collegiate swimmers. Because evidence suggests that compressive force develops under the coracoacromial arch when the arm elevated above 90º of arm elevation is maximally internally rotated, such shoulder configurations were measured for each participant. A series of scapulohumeral angles measured with this procedure were compared with the corresponding angles exhibited during fully tethered front-crawl swimming to identify the scapulohumeral angles indicative of subacromial compression. Additional comparison was performed without taking the scapular motion into account. Scapulohumeral angles indicative of subacromial compression were observed in 15 participants, accounting for 7.7 ± 7.1% of stroke cycle time. This duration was significantly less than the corresponding duration identified without having taken the scapular motion into account (22.6 ± 13.8% of stroke cycle time). The difference was due primarily to the unique movements of the scapular to accommodate demands imposed by stroke motions, and this supported the hypothesis.
概要：This technical report introduces a method for measuring the three-dimensional articular motions of the shoulder complex during swimming. Eleven collegiate swimmers performed front-crawl strokes at maximal effort and their shoulder motions were measured with an electromagnetic tracking device. Sensors were attached to the sternum, acromia and humeri to determine their relative positions and orientations. A cart carrying the components of the device was pushed back-and-forth along the poolside, so that the sensors attached to the swimmer could be detected within the electromagnetic field. The stroke-to-stroke reliability of the measured articular motions was determined for each swimmer. The accuracy of the device was tested by measuring the relative positions and orientations of multiple sensors fixed on a wooden stick moving above and below the water surface. The measured values were compared with pre-determined fixed values. The coefficient of variance for the joint angles between stroke cycles was <10% of the total range of movement. Within a range of 1282 mm from the transmitter, the root-mean-square error of measurement was 0.7° for orientation and 4 mm for position, both of which were superior to optical measurements. This method is accurate and reliable for measuring the kinematics of the shoulder complex during swimming.
概要：Swimming techniques require a fine coordination of various joints to maximize performance and reduce the risk of injury. A large number of variables are necessary to describe the coordination of multiple joints during swimming strokes. Since joints move in harmony with other joints during swimming, it should be possible to describe the coordination of multiple joint motions with a fewer characteristic variables. The purpose of the study was to find the characteristic variables to describe the coordination of multiple joint motions of front-crawl sprint swimmers. Twenty-four members of collegiate swimming team were asked to swim a front-crawl technique with their maximal effort in a 25m course. An electromagnetic tracking device was used to record the joint angles in three-dimensions at 240 Hz. Three stroke cycles were extracted for each swimmer and the total of 72 stroke cycles were analyzed. Sixteen variables including the joint angles of elbow, shoulder complex and torso were calculated for each stroke cycles. A principal component analysis was used to simplify the variables of joint angles for each stroke cycles. The scores of principal components were compared between the stroke cycles performed by the front-crawl sprint swimmers and the others. Results showed that 6 principal components account for 77% of the variance. Front-crawl sprint swimmers showed a smaller glenohumeral joint elevation angle, less rotation range of the upper limb and torso lateral tilt mainly in one side during the pull phase of stroke cycles.
ISBS-Conference Proceedings Archive査読有り2018年05月-2018年09月
概要：The present study was conducted to describe characteristics of scapular kinematics and scapulohumeral rhythm (SHR) in baseball pitchers and swimmers. The participants were 16 swimmers, 19 baseball pitchers and 8 non-athletes. Each participant was asked to perform three tasks, arm abduction, shoulder horizontal abduction (HA) and shoulder internal/ external rotation (IR/ER). An electromagnetic tracking device was used to record the 3D data of shoulder complex. The SHR during the arm abduction and the range of motion for shoulder complex were determined for each task. The results showed that swimmers had significantly greater ranges of shoulder HA and scapular upward rotation while pitchers had a significantly greater range of shoulder ER and a significantly smaller range of shoulder IR. There was no obvious difference in SHR between the groups.
Journal of Applied Biomechanics査読有り32(1)p.50 - 582016年02月-2016年02月
概要：© 2016 Human Kinetics, Inc.Low back pain is a common problem among competitive swimmers, and repeated torso hyperextension is claimed to be an etiological factor. The purpose of this study was to describe the three-dimensional torso configurations in the front crawl stroke and to test the hypothesis that swimmers experience torso hyperextension consistently across the stroke cycles. Nineteen collegiate swimmers underwent 2 measurements: a measurement of the active range of motion in 3 dimensions and a measurement of tethered front crawl stroke at their maximal effort. Torso extension beyond the active range of torso motion was defined as torso hyperextension. The largest torso extension angle exhibited during the stroke cycles was 9 ± 11° and it was recorded at or around 0.02 ± 0.08 s, the instant at which the torso attained the largest twist angle. No participant hyperextended the torso consistently across the stroke cycles and subjects exhibited torso extension angles during tethered front crawl swimming that were much less than their active range of motion. Therefore, our hypothesis was rejected, and the data suggest that repeated torso hyperextension during front crawl strokes should not be claimed to be the major cause of the high incidence of low back pain in swimmers.
ISBS-Conference Proceedings Archive査読有り34(1)p.569 - 5722016年-2016年
概要：The purposes of the study were to describe glenohumeral joint motion during front crawl swimming and to determine if the glenohumeral joint motion could be predicted by the humero-thoracic motion using linear regression model. Fourteen swimmers were asked to perform a resisted front crawl swimming. Three-dimensional motions of shoulder complex were measured with an electromagnetic tracking devise. The results showed that humerus and scapula did not move in a set ratio during front crawl swimming and the glenohumeral joint motion could not be predicted accurately from the humero-thoracic motion. A characteristic movement pattern was observed in the catch phase in which the humerus moved caudally behind the scapular plane while moving in front of the torso. This movement pattern may facilitate internal rotation of the shoulder to execute the catch and pull vigorously.
ISBS-Conference Proceedings Archive査読有り2013年-2013年
概要：The purposes of the present study were to measure the glenohumeral joint motion exhibited during front-crawl swimming and to re-examine the instances at which the subacromial structures were experiencing impingement. A series of glenohumeral configurations indicative the impingement were measured to define the so called “boundary range of motion,” which was used to identify if the glenohumeral configurations exhibited at any instant during swimming is indicative of impingement. A simplified kinematic model composed of right scapula, right humerus and thorax was used to describe the shoulder configuration for three collegiate swimmers. The results showed that impingement occurred for 0~ 12% of the stroke time during the front-crawl for the three subjects.
Chinese journal of sports medicine査読有り31(2)p.101 - 1052012年-2012年
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