1,721,078 research outputs found
Glenohumeral joint internal rotation and scapular kinematics in elite wheelchair tennis players
No full textShoulder pain and function in professional wheelchair tennis players
No full textWheelchair use places large demands on the shoulder with up to 72% of users experiencing shoulder pain. Wheelchair users who take part in sport place additional demands the shoulder both in terms of the number of load cycles and the amplitude of forces. However, very little is known of the effects of sport participation on shoulder pain and function of wheelchair which may increase pain or provide a protective benefit for the shoulder and reduce pain. The aim of the study was to investigate the presence of shoulder pain and bilateral function of the shoulder in professional wheelchair tennis players. The presence of shoulder pain and impingement was recorded in eleven wheelchair tennis players using the Wheelchair Users Shoulder Disability Index (WUSPI) questionnaire and clinical examination. Kinematics of the scapula during humeral elevation and lowering in the scapular plane were obtained utilising the acromion marker cluster technique. A repeated measures ANOVA with main effects of side and humeral elevation angle was used to determine differences in kinematics between the dominant and non-dominant sides. Results of the self-reported shoulder pain questionnaire demonstrated participants experienced little pain that interfered with daily life with an average WUSPI score of 28 ± 13.8. Clinical examination demonstrated all impingement tests were negative for all participants. Kinematic analysis showed that the scapula was in a significantly greater posterior tilt orientation of 3.9° on the dominant side compared to the non-dominant side during humeral elevation and lowering. Although not statistically significant, the scapula was more internally rotated by 7.2° on the non-dominant side compared to the dominant side. There were no significant differences or trends between sides for scapular upward rotation. Despite the increased demands on the shoulder through sport participation and asymmetry in scapular kinematics there was an absence of pain or clinical signs of shoulder impingement within this professional sporting group. Further work is needed to understand the role of sport participation and exercise on shoulder pain and function in wheelchair users
The Influence of Elbow Flexion and Arm External Rotation on Peak Elbow Valgus Torque and Ball Velocity in Baseball Pitching
No full textIntroduction Elbow injury, especially Ulnar Collateral Ligament (UCL) tear, is very common in baseball pitching. This is often attributed to high valgus torques repetitively stressing the ligament. The goal of this study was to research the effect of Elbow Flexion (EF) and arm External Rotation (ER) angle on Peak Valgus Torque (PVT) as well as ball velocity, using a three-folded approach. Methods Motion data of 12 Dutch A and AAA team pitchers were collected (29 pitches in total). Firstly, the relationships between the variables and outcomes were statistically evaluated with Generalized Estimating Equations (GEE). Secondly, simplified movements and EF and ER variations were input to a two-segment model, which was based on the hypothesis that valgus torque is generated by inertial effects from external rotation deceleration and forearm forward acceleration. Lastly, for one pitch per player, ER and EF angles were varied in simulations.Results Statistical significance was only observed for higher EF as a predictor of increased PVT and higher ER as a predictor of decreased ball velocity. In the two-segment model, PVT increased for higher EF and decreased for higher ER. The simulations showed different effects between pitchers, however, most trends were similar to those of the two-segment model. Ball velocity was maintained or increased withhigher EF, while the influence of ER on ball velocity differed between players.Conclusion The two-segment model led to a more in-depth insight in the many factors influencing PVT in pitching. The results of this study suggest that higher ER and lower EF could lead to lower PVT, without necessarily giving in on performance. However, the results showed differences between pitchers. As previous studies reported opposite trends regarding ER, we believe that this discussion should be re-opened. Our findings suggest that some pitchers are more prone to elbow injury than others and that pitchers might be able to lower injury-risk by adapting their pitching technique
Evaluating the use of a piezo-resistive pressure sensor system for performance feedback in long track speed skating
No full textIn the sport of long track speed skating, in recent years there has been an increasing desire for training tools which provide deeper technical insight of the skating movement to the athlete and coaches. In previous literature a variety of measurement systems have been presented; one such system included the instrumented klapskate developed at the Delft University of Technology. Alongside the implementation of this new instrumented klapskate, a simplified piezo-resistive pressure sensor system has been applied with high performance Dutch speed skaters; however, to this point the best application of such a system has not been shown. This research examined the potential ways in which this simplified system may provide valuable feedback to a skater, with consideration for the feedback currently available within the sport. Through a combination of bench and on-ice testing, the system was evaluated for its ability to predict skating forces (normal, lateral, and absolute), the center of pressure of force application, peak stroke force, and finally, contact time for individual strokes. Despite an inability to generate a full profile of skating force, the PRPS system provided reasonable estimations of peak stroke normal (RMSE = 50.2 N) and absolute (RMSE =50.5 N) forces in the straights, while in the curve, peak normal (RMSE = 129.4) and absolute (RMSE = 131.5 N) force estimates were less accurate. Stroke timing was predicted with accuracy, giving minor underestimation in both the straight (RMSE = 0.0671 s) and curves (RMSE = 0.0474 s). Center of pressure measurement was largely unsuccessful when attempted on the bench using a tensile load cell, however estimations applied to on-ice data yielded trends in center of pressure position consistent with previous literature, suggesting future viability as a feedback parameter. For future work, a larger sample size and further on-ice testing would be recommended for verification and improved development of this prototype system.Mechanical Engineerin
Biomechanical analysis of shoulder arthroplasty
No full textAbstract not availableMechanical Maritime and Materials Engineerin
The relation between medio-lateral trunk movements and ankle power and work during the push off phase of gait
No full textJoint kinetics measured during level walking demonstrates that the main source of energy occurs around the ankle joint, i.e. a large power burst during push off. This power burst can be divided into two mechanisms; pre-emptive push off and a push off to accelerate the leg into swing. This division is marked by the contralateral initial contact, i.e. the impactful start of weight transfer to that foot. This impact is the main energy absorbing event during gait that will be decreased by a pre-emptive push off. It is hypothesized that the medio-lateral position of the Center of Mass of the body controls the weight shift and thus the division of the ankle power into these two mechanisms. Since the trunk has a rather large mass compared to other body segments, the position of the Center of Mass of the trunk has a large influence on the total body Center of Mass. This led to the hypothesis of this study: the trunk controls the ankle power during gait. To verify this hypothesis eleven healthy subjects participated in this study, where gait kinematics and kinetics were obtained using motion capture and force plates. A lower- and upper-trunk was defined, based on a dedicated marker model. The tasks included normal walking as well as conditions to influence the medio-lateral trunk movements and the ankle power during gait. Differences and relations between the amount of ankle work during push off, the amount of ankle work within the two different mechanisms, maximum ankle power, and medio-lateral trunk angles for the different walking conditions were calculated. The amount of ankle work during push off is significantly – but modestly – related to the maximum amplitude of the lower trunk angle. This suggests that with an increasing trunk angle the amount of ankle work decreases. This relation was not found for the upper trunk angle or the Center of Mass of the entire upper body. The maximum ankle power during push off also has a small but significant relation with medio-lateral trunk movements. It can be concluded that with increasing medio-lateral trunk movements the amount of ankle power and work is slightly decreased. The division of the ankle work during push off into two parts is not significantly related to any increase in medio-lateral trunk movements. In the end, these results cannot point to a strong relation between ankle power or work and medio-lateral trunk movements. However, this is an exploratory study and to draw definite conclusions about this relation more extensive research is needed. It might also be interesting to investigate the possibilities of using increased medio-lateral trunk movements to relieve the ankle joint during walking.Biomedical Engineering | BioMechatronic
Identifying Low-Back Stabilization in Low-Back Pain and the Influence of Tactile Information
Full text linkDieen, J.H. van [Promotor]Veeger, H.E.J. [Promotor
Upper extremity load during wheelchair-related tasks in subjects with a spinal cord injury
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