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A.J.R. Leenen

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6 records found

Are UCL Injuries a Matter of Bad Luck?

The Role of Variability and Fatigue Quantified

Journal article - B. van Trigt, A.J.R. Leenen, Marco J.M. Hoozemans, F.C.T. van der Helm, H.E.J. Veeger, H.E.J. Veeger

Upper extremity injuries are common in baseball. One of these is the ulnar collateral ligament (UCL) injury. In the field of sports injuries, most research focuses on average kinematics and kinetics between subjects, whereas focusing on within-subject variability appears to be mo ...

Testing for no effect in regression problems

A permutation approach

Journal article - M.G. Ciszewski, J. Söhl, A.J.R. Leenen, B. van Trigt, B. van Trigt, G. Jongbloed

Often the question arises whether (Formula presented.) can be predicted based on (Formula presented.) using a certain model. Especially for highly flexible models such as neural networks one may ask whether a seemingly good prediction is actually better than fitting pure noise or ...

Fastball pitching performance only slightly decreases after mobility impediment of the pelvis and trunk—Do (catch-up) compensation strategies come into play?

Journal article - A.J.R. Leenen, B. van Trigt, Marco J.M. Hoozemans, H.E.J. Veeger

Background: Baseball pitching performance can be mechanically explained by the summation of speed principle and the principle of optimal coordination of partial momenta. Impeding optimal energy generation or transfer by or between the pelvis and trunk segments could provide valuable insight into possible compensation or catch-up mechanisms that may manifest themselves based on these principles. Aim: The aim of the present study was to explore the effects of experimentally impeding the mobility of and between the pelvis and trunk segments (1) on ball speed and mechanical peak joint power, and (2) on mechanical peak load of the elbow and shoulder joints at maximal external rotation (MER) during fastball pitching. Methods: Eleven elite baseball pitchers (mean age 17.4, SD 2.2 years; mean pitching experience 8.9, SD 3.0 years) were instructed to throw at least 15 fastballs as fast and accurately as possible under two conditions. One condition involved impeding the mobility of the pelvis and trunk segments to hamper their ability to rotate independently, which consequently should affect the separation time, defined as the time interval between the pelvis and trunk peak angular velocities. In the other condition, pitchers threw unimpeded. Ball speed, mechanical peak joint power and peak net moment of the elbow and shoulder at MER were compared between conditions using Generalized Estimating Equations (GEE). Results: In the impeded pitching condition, the mean difference of the separation time was 12.4 milliseconds [95% CI (4.0, 20.7)] and for ball speed 0.6 mph [95% CI (0.2, 0.9)] lower compared to the unimpeded condition. Only the peak pelvic angular velocity, in addition to the trunk, upper arm and forearm, was 45 deg/s [95% CI (24, 66)] higher impeded condition. The mean differences of the joint power and net moments at the shoulder and elbow did not reach statistical significance. Conclusion: In elite adolescent baseball, the observed pitching performance after experimentally impeding pelvic and trunk mobility undermines a potential distal catch-up strategy based on the summation of speed principle. The increased peak pelvic angular velocity may indicate a compensation strategy following the optimal coordination of partial momenta principle to practically maintain pitching performance.@en

Cross-Cultural Adaption and Validation of the Dutch Version of the Kerlan-Jobe Orthopaedic Clinic Questionnaire in Juvenile Baseball Pitchers

Journal article - A.J.R. Leenen, Amber Hurry, Femke van Dis, Erik van der Graaff, H.E.J. Veeger, Marco J.M. Hoozemans

Monitoring the performance and functional status of baseball pitchers’ upper extremity is important in maintaining the athlete’s health and performance. This study validated a Dutch translation of the original English Kerlan-Jobe Orthopaedic Clinic (KJOC) against the previously v ...

Effects of a Disturbed Kinetic Chain in the Fastball Pitch on Elbow Kinetics and Ball Speed

Journal article - A.J.R. Leenen, B. van Trigt, Marco J.M. Hoozemans, H.E.J. Veeger

The purpose of the present study was to investigate the effect of an experimentally imposed kinetic chain disturbance in baseball pitching on ball speed and elbow kinetics. The experimental design consisted of two (within-subject) conditions. In one condition there was no manipul ...

Magnitude and variability of individual elbow load in repetitive baseball pitching

Journal article - B. van Trigt, Thomas van Hogerwou, A.J.R. Leenen, Marco J.M. Hoozemans, F.C.T. van der Helm, H.E.J. Veeger

In baseball pitchers the elbow is exposed to high and repetitive loads (i.e. external valgus torque), caused by pitching a high number of balls in a practice session or game. This can result in overuse injuries like the ulnar collateral ligament (UCL) injury. To understand injury ...

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Examination of shoulder muscles’ activity during a baseball pitch using musculoskeletal modeling

Master thesis - Z.A. Tyczyńska, H.E.J. Veeger, A.J.R. Leenen

A baseball pitch is an explosive and dynamic motion during which one of the highest angular rates achieved by the human body in sports activity was noted. The nature of the baseball pitch puts shoulder structures at risk, and one of the most common injuries among pitchers is a rotator cuff tear, frequently connected with internal impingement. It has been found that the amount of internal impingement increases for the angle of horizontal abduction beyond the coronal plane. To better understand the mechanics in the shoulder that leads to excessive horizontal abduction, it was decided to study muscle behavior (activation and produced torque) during the acceleration and deceleration phases of a baseball pitch. The study focused on muscles that are believed to have the most significant contribution during the aforementioned phases: pectoralis major and rotator cuff muscles (infraspinatus, supraspinatus and teres major). The analysis was performed with the use of the Thoracoscapular Shoulder Model implemented in OpenSim software. About 20 pitches of 5 different baseball pitchers were simulated based on the collected marker motion data. Visible differences in the horizontal abduction/adduction angle were found between participants, with the angle of horizontal abduction between -10 degrees to 18 degrees at the moment of maximal external rotation (MER). Next, the muscle length was analyzed. The normalized muscle length of the rotator cuff muscles at MER was found to be similar to one found in the literature, as well as the changes in muscle length over time. However, discrepancies were found in the pectoralis major behavior. The conclusion was drawn that the thoracic part of the pectoralis major is too long. Moreover, it was found that the pectoralis major does not wrap around the humeral head and shaft for the horizontal abduction angle exceeding daily-live tasks. Next, static optimization was done to find the activation of the muscles in the glenohumeral joint and, consequently, to calculate the contribution of the individual muscles to the total torque in the joint. The contribution of the rotator cuff muscles was in accordance with the information found in the literature. However, the pectoralis major was not as active as expected. Instead of it, high activity of the deltoideus muscle and coordinate actuators was found. The results indicate that the pectoralis major was not working as expected, and other muscles needed to compensate for its normal function. Several improvements to the model and data collection were proposed. For the model development, it is suggested to ensure wrapping around the humeral head and shaft for the pectoralis major. Moreover, further evaluation of the model scaling is recommended, as problems with scaling the thoracic part of the pectoralis major were found. It is believed that after their implementation, it will be possible to find a potential correlation between the range of horizontal abduction and muscle activity while using the methodology and tools presented in this study.