Cocking Phase Research Articles

Are there kinematic and kinetic parameters correlated with racket velocity during the tennis serve? A preliminary comparison between a slow and a fast serve for performance improvement.

The tennis serve is a complex motion with numerous rotations which are important to manage for performance. The main aim of this study was to investigate kinematic parameters, including the evolution of the center of gravity, and kinetic parameters correlated with racket velocity over all phases of the tennis serve. The secondary objective was to find out which of the correlated parameters differed between a slow and a fast serve. The advantage of such an approach would be to propose biomechanical parameters that coaches and teachers could use to optimize performance or learn how to serve. Quantitative analysis was carried out on 5 flat serves performed by four ranked players using an optoelectronic system (82 markers located on whole body and racket) composed of 10 infrared cameras (150 Hz) and two force platforms (750 Hz). A descriptive statistical analysis highlighted 11 very large and almost perfect correlations with racket velocity: vertical ground reaction force of back foot in release backward, trunk axial rotation during loading phase, back and front knee flexions, dominant shoulder and hip mediolateral rotation during cocking phase, and center of gravity vertical velocity, dominant shoulder medial rotation velocity, dominant elbow flexion, trunk flexion/extension and axial rotation during acceleration phase. Differences were observed for some of the correlated parameters between slow and fast serve. Consequently, all these correlated kinematic and kinetics parameters constitute information that coaches, instructors and athletes can use to improve, optimize or teach the tennis serve.

Literature review of specific techniques in catching and throwing in infield defense in baseball - retrospective article

<p>目的：內野手可以是整個棒球守備的核心，棒球守備各階段全身上下的協調，有許多值得探討的專項技巧。方法：本研究使用Google scholar，以Baseball infielder、內野、野球守備、內野捕球、守備ゴロ等關鍵字，搜尋台灣、日本、美國三國關於棒球內野守備專項技巧的文獻做歸納，以不同角度探討內野守備的專項技巧：一、內野守備接球，二、內野守備傳球，三、守備的分期與各分期之動作控制。結果：本篇回顧性論文發現，一、移動腳步到好接球的彈跳點是良好守備的關鍵。二、減少軸心腳在接球位置上的變化和較為前面的接球點，對於接球的穩定性至關重要，甚至會影響到後續傳球的動能。三、精簡接傳的動作相較於增加傳球球速可能可以更能有效減少整體守備時間。四、優秀選手在接球的過程中會儘早讓軸心腳著地，並前期和中期將重心保留在軸心腳。五、內野手傳球在前導腳接觸時，軀幹向後扭轉和肘部伸展角度都會比投手小。結論：無論是接球前腳步移動的節奏和精確性，還是接球時的接球點和接短彈跳的能力，甚至是軀幹和骨盆前傾的時機點，對於內野守備過程都產生一定的影響。建議在日常練習時，就能將接短彈跳、腳步移動，納入訓練課表中，並且在動作過程中，加以檢視軀幹的姿勢，方能在比賽時擁有良好的守備表現。</p> <p> </p><p>The standing throw with run-up is the best approach to evaluate the performance of energy transfer and the efficiency of throwing motions for handball players. Purpose: This research aims at analyzing the usage of the standing throw with run-up among the handball players in Taiwan. The roles of body kinematics, strength of core muscles and standing balance of the drive leg played in the standing throw with run-up are also discussed. Methods: Nine Division I handball players from college went through a series of tests. The motions and the speed of the handball throwing were detected by a 3D electromagnetic motion analysis system and a sports radar gun, respectively. The maximum isometric muscle strength of trunks and hips were measured by a torque sensor and a home-made device of strength measurement. The standing balance of the drive leg was measured by a force plate with a mat. Results: The maximal shoulder external rotation angle in the arm cocking phase, the maximal trunk rotation velocity in the arm acceleration phase and the maximal shoulder horizontal adduction velocity showed moderate positive relationships with the ball velocity. The strength of back muscles had a moderate negative relationship with the ball velocity. The correlation between the balance ability of the drive leg and the ball velocity was not observed. Conclusion: The importance of proximal segments to the standing throw with run-up is analyzed by kinematical analysis. It is suggested that the energy of handball throwing is generated by the upper extremities or other limb segments in the processes of the standing throw with run-up. Our findings can serve as a helpful reference for both coaches and players.</p> <p> </p>

Long Head of the Biceps Tendon Plays a Role in Stress Absorption and Humeral Head Restriction during the Late Cocking and Deceleration Phases of Overhead Throwing: A Finite Element Study

BackgroundEmerging evidence suggests that the long head of the biceps (LHBT) may play a role in stabilizing the glenohumeral joint, and this has led to controversy around the efficacy of biceps tenotomy for superior labral anterior and posterior (SLAP) lesions. Therefore, the aim of this finite element analysis (FEA) study was to determine the stress absorption and humeral head translation restriction effects of the LHBT within the glenohumeral joint during the late cocking and deceleration phases of overhead throwing with a view to resolving the controversy around tenotomy. MethodsEight FEA models were created using computed tomography and magnetic resonance imaging data from normal glenohumeral joints. The models represented four LHBT conditions: uninjured, subpectoral tenodesis, tenotomy, and type II SLAP lesions. The late cocking and deceleration phases of the overhead throwing were simulated for each model. The impacts of the four LHBT conditions on glenohumeral joint stress absorption and humeral head displacement restriction were studied based on 1) stress and related distributions on the cartilage, labrum, capsule, and LHBT and 2) humeral head translation variation. ResultsThe FEA analysis showed that the magnitude of the contact stress on the articular cartilage, labrum, and capsule was the lowest in the uninjured models, followed by the subpectoral tenodesis, tenotomy, and type II SLAP lesion models. Humeral head translation was the most restricted in the subpectoral tenodesis models, followed by the tenotomy and type II SLAP lesion models. ConclusionFinite element analysis demonstrated that the LHBT plays a significant role in stress absorption and displacement restriction in the late cocking and deceleration phases of overhead throwing. Subpectoral tenodesis of the LHBT exhibited lesser amount of stress and humeral head translation than those of tenotomy, thereby making it a better option for patients who engage in overhead throwing.

Kinematics of the Tennis Serve Using an Optoelectronic Motion Capture System: Are There Correlations between Joint Angles and Racket Velocity?

The serve is the most important stroke in tennis. It is a complex gesture consisting of numerous rotations with a wide amplitude, which are important to manage for performance. The aim of this study was to investigate whether correlations exist between joint kinematic parameters and racket velocity. A quantitative kinematics analysis of four ranked players (two boys and two girls) was carried out using an optoelectronic system composed of 10 cameras (150 Hz). Five flat serves per player were analyzed. Eighty-two markers were located across the 15 body segments and on the racket. A descriptive statistical analysis including a correlation analysis was carried out between joint angles and racket kinematic parameters (vertical position, velocity, and acceleration) during the cocking and acceleration phases. Ten very high (0.7 < r < 0.9) and three almost perfect (r > 0.9) correlations were found. Shoulder and hip axial rotations, knee flexion, and trunk extension were correlated linearly with racket vertical position and velocity during the cocking phase. For the acceleration phase, elbow flexion, trunk flexion/extension, and trunk axial rotation were linked to racket kinematics. Some of these parameters showed differences between slow and fast serves. These parameters, which are involved in transmitting ball velocity, are important to consider for tennis players and coaches in training programs, education, and performance enhancement.

Correlation between run-up speed and throwing distance of elite javelin athletes

&lt;p&gt;目的：本研究探討台灣優秀標槍選手助跑速度與投擲距離之相關性。方法：8位國內優秀標槍選手 (身高：176.2 &amp;plusmn; 4.5公分，體重：87.7 &amp;plusmn; 10.7公斤，年齡：21.1 &amp;plusmn; 3.7歲，平均投擲距離：68.8 &amp;plusmn; 6.9公尺)，本研究採用實際比賽進行數據收集，本研究使用高速攝影機 (60Hz) 紀錄投擲標槍助跑過程，透過影像分析獲得助跑距離及時間。本研究採用相依樣本t檢定比較預賽及決賽的助跑速度及投擲表現及使用皮爾森積差相關分析比較助跑速度及投擲表現之相關性，顯著水準訂為 &amp;alpha; = .05。結果：研究結果發現，預賽與決賽的投擲表現顯著大於決賽有顯著差異 (p &lt; .05)，但預賽與決賽的助跑速度無顯著差異 (p &gt; .05)，另外，預賽與決賽的投擲距離與助跑速度相關性沒有顯著差異。結論：當助跑速度越快不會增加投擲距離。選手可能會有個別最佳的助跑速度。&lt;/p&gt;&lt;p&gt;The standing throw with run-up is the best approach to evaluate the performance of energy transfer and the efficiency of throwing motions for handball players. Purpose: This research aims at analyzing the usage of the standing throw with run-up among the handball players in Taiwan. The roles of body kinematics, strength of core muscles and standing balance of the drive leg played in the standing throw with run-up are also discussed. Methods: Nine Division I handball players from college went through a series of tests. The motions and the speed of the handball throwing were detected by a 3D electromagnetic motion analysis system and a sports radar gun, respectively. The maximum isometric muscle strength of trunks and hips were measured by a torque sensor and a home-made device of strength measurement. The standing balance of the drive leg was measured by a force plate with a mat. Results: The maximal shoulder external rotation angle in the arm cocking phase, the maximal trunk rotation velocity in the arm acceleration phase and the maximal shoulder horizontal adduction velocity showed moderate positive relationships with the ball velocity. The strength of back muscles had a moderate negative relationship with the ball velocity. The correlation between the balance ability of the drive leg and the ball velocity was not observed. Conclusion: The importance of proximal segments to the standing throw with run-up is analyzed by kinematical analysis. It is suggested that the energy of handball throwing is generated by the upper extremities or other limb segments in the processes of the standing throw with run-up. Our findings can serve as a helpful reference for both coaches and players.&lt;/p&gt; &lt;p&gt;&amp;nbsp;&lt;/p&gt;

Proximal to distal sequencing impacts on maximum shoulder joint angles and the risk of impingement in baseball pitching involving a scapular independent thoracohumeral model.

Hyperangulation of the scapulohumeral joint due to poor coordination of the scapula during throwing motion is claimed to be a major cause of internal impingement in baseball pitchers. However, evidence of injurious scapular kinematics is lacking, particularly regarding how hyperangularion actually occurs in full-effort pitching. The purpose of this study was to describe sequential scapular motions involved in attaining maximum joint angles during pitching and the implications for internal impingement in elite baseball pitchers. An electromagnetic goniometer system computed kinematics for pelvis, thorax, scapulae, arms, and forearms during baseball pitching in 72 pitchers. Internal impingement risk was assessed based on kinematic characteristics of internal impingement quantified in a cadaveric study. The pelvis, thorax, and scapula rotated in the proximal-to-distal sequence. Large forearm layback observed near the end of the cocking phase (182 ± 27°) was achieved with a submaximal scapulohumeral external rotation (98 ± 14°). In the next 0.027 ± 0.007 s, forward thoracic rotation and then scapular rotation caused increased scapulohumeral external rotation to a maximum of 113 ± 14°. Here, humeral horizontal adduction and scapula protraction occurred simultaneously preventing the humerus from lagging further behind the scapula. Only one participant reached critical hyperangulation beyond which internal impingement was reported to occur. Most elite pitchers safely attained the fully cocked position, yet off-timed recoiling of scapular protraction caused hyperangulation in full-effort pitching. Therefore, proximal-distal sequencing between the scapula and humerus should be evaluated to lessen the risk of internal impingement in baseball pitchers.

The biomechanical analysis of the standing throw with run-up

&lt;p&gt;為了解手球選手在投擲動作上的效率，墊步射門是檢視能量傳遞好壞的最佳方式。目的：分析臺灣手球選手使用墊步射門的情形，以及探討肢體運動學，核心肌群肌肉力量和前導腳站立平衡能力在墊步射門中的重要性。方法：9 位大專男子甲組選手 (年齡 22.0 &amp;plusmn; 1.3 歲、身高 177.1 &amp;plusmn; 3.1 公分、體重 78.4 &amp;plusmn; 5.1 公斤)，以三度空間電磁場動作分析系統擷取墊步射門動作，並以雷達測速槍測量球速；以力矩傳感器搭配特製測力裝置測量軀幹及髖關節各肌群之最大等長肌力；以軟墊置於測力板上測量前導腳站立平衡能力。使用肯德爾相關係數探討射門運動學參數、核心肌群肌肉力量和前導腳站立平衡能力與墊步射門球速之相關性，顯著水準定在 p &lt; .05。結果：引臂期的肩膀最大外轉角度 (Kendall’s tau-b = .54)，手臂加速期的軀幹最大旋轉速度 (Kendall’s tau-b = .54)、肩膀最大水平內收速度 (Kendall’s tau-b = .69) 與射門球速皆有中度的正相關。背部肌肉力量與射門球速有中度的負相關 (Kendall’s tau-b = -.57)。前導腳平衡能力參數與射門球速皆無相關性存在。結論：透過運動學分析了解到大專男子甲組選手在執行墊步射門時的動作表現，並發現身體近端對於墊步射門的重要性。建議應加強墊步射門時的軀幹動作，藉由較快的軀幹旋轉速度來帶動上肢的投擲表現，以提升射門球速。&lt;/p&gt; &lt;p&gt;&amp;nbsp;&lt;/p&gt;&lt;p&gt;The standing throw with run-up is the best approach to evaluate the performance of energy transfer and the efficiency of throwing motions for handball players. Purpose: This research aims at analyzing the usage of the standing throw with run-up among the handball players in Taiwan. The roles of body kinematics, strength of core muscles and standing balance of the drive leg played in the standing throw with run-up are also discussed. Methods: Nine Division I handball players from college went through a series of tests. The motions and the speed of the handball throwing were detected by a 3D electromagnetic motion analysis system and a sports radar gun, respectively. The maximum isometric muscle strength of trunks and hips were measured by a torque sensor and a home-made device of strength measurement. The standing balance of the drive leg was measured by a force plate with a mat. Results: The maximal shoulder external rotation angle in the arm cocking phase, the maximal trunk rotation velocity in the arm acceleration phase and the maximal shoulder horizontal adduction velocity showed moderate positive relationships with the ball velocity. The strength of back muscles had a moderate negative relationship with the ball velocity. The correlation between the balance ability of the drive leg and the ball velocity was not observed. Conclusion: The importance of proximal segments to the standing throw with run-up is analyzed by kinematical analysis. It is suggested that the energy of handball throwing is generated by the upper extremities or other limb segments in the processes of the standing throw with run-up. Our findings can serve as a helpful reference for both coaches and players.&lt;/p&gt; &lt;p&gt;&amp;nbsp;&lt;/p&gt;

Biomechanical Characteristics of Scapular and Glenohumeral Movements during Pitching Motion in Injury-prone College Baseball Pitchers.

The coordination of glenohumeral (GH) and scapular movements is central to the injury prevention of baseball pitchers. However, there is no objective data establishing the direct relationship between pitching injuries and associated GH and scapular movements. Therefore, this study demonstrated the biomechanical differences in the scapular and GH movements during pitching between injury-prone pitchers and healthy college baseball pitchers. A total of 30 collegiate baseball pitchers were classified into two groups according to their injury status: injury-prone group (n = 15) and control group (n = 15). We obtained pitching motion data using three-dimensional motion analysis technique. The horizontal abduction angles of the GH joint during cocking and acceleration phases were considerably greater in the injury-prone pitchers (19.0° at stride foot contact [SFC], -4.0° at maximum external rotation [MER], and -0.3° at ball release) than those in healthy controls (11.7° at SFC, -10.0° at MER, and -6.9° at ball release). Additionally, in the cocking phase, the amount of angular change in the scapular external rotation (ER) was significantly smaller in the injury-prone group than that in the control group (mean difference, -13.0). These results suggest that the injury-prone pitchers have less internal rotation of the scapula and a more horizontal abduction of the GH joint during the cocking and acceleration phases. Therefore, sports medicine practitioners may need to pay considerable attention to the coordination of scapular and GH horizontal movements during pitching for prevention of shoulder injuries.

Interindividual differences in upper limb muscle synergies during baseball throwing motion in male college baseball players

Throwing is a fundamental human motor behavior that has evolved to aid hunting and defense against predators. In modern humans, accurate throwing is an important skill required in many sports. However, the spatiotemporal coordination of muscles during baseball throwing has not been fully elucidated. We herein aimed to identify the muscle synergies involved in baseball throwing and determine whether their spatiotemporal patterns are shared among individuals. Ten college baseball players participated in this study. Electromyographic activity was recorded from 13 ipsilateral upper limb muscles during throwing using full effort. Non-negative matrix factorization was used to extract the motor module composition and temporal activation patterns during baseball throwing, followed by k-means analysis to cluster the extracted motor modules based on their similarity. Four motor modules were extracted for each player. These were classified into four clusters (Clusters 1–4), each reaching the peak activity sequentially from the early cocking phase to ball release. Spatiotemporal interindividual similarity in the muscle synergy cluster comprising the muscles activated during the transition from early cocking to late cocking (Cluster 2) was significantly lower than that in the other clusters. There was no individual-specific muscle synergy. These results suggest that the skilled baseball throwing motion acquired through years of practice may consist of four basic muscle synergies that are common among individuals with some differences in their spatiotemporal patterns.

The short-term effectiveness of scapular focused taping on scapular movement in tennis players with shoulder pain: A within-subject comparison.

This study aimed to investigate the short-term effectiveness of scapular focused taping (SFT) on scapular position and kinematics during the tennis serve among professional players with and without shoulder pain. The cohort included 7 players who had no history of non-shoulder pain (NSP) and 6 players with shoulder pain (SP). All participants performed tennis flat serves while the Qualisys motion capture system recorded three-dimensional scapular kinematic data according to the International Society of Biomechanics recommendations. SFT was applied to the participants’ torso aligned with the lower trapezius, and the same movements were repeated. In the SP group, the scapula was tilted more posteriorly after the application of SFT as compared to before at ball release and maximally externally rotated humerothoracic joint during tennis serve (t = −5.081, P = .004 and t = −2.623, P = .047, respectively). In the NSP group, the scapula was tilted more posteriorly with SFT as compared to without at first 75% timing of the cocking phase and maximally externally rotated humerothoracic joint (t = −3.733, P = .010 and t = −2.510, P = .046, respectively). And the SP group exhibited a more rotated scapula externally after the application of SFT as compared to before at Ball impact (t = 5.283, P = .003). SFT had a positive immediate effect on the scapular posterior tilting and external rotation during certain phases of the tennis serve among tennis athletes with and without shoulder pain. These findings may help clinicians and sports practitioners to prevent and rehabilitate shoulder injuries for overhead athletes.Level of evidence: Level III; Case-Control Design; Comparative Study.

Spike Arm Swing Techniques of Olympics Male and Female Elite Volleyball Players (1984-2021).

In the last decades, indoor volleyball has experienced significant rule changes and a high player specialization in both sexes. Different spike attack arm swing techniques have developed which might affect performance and risk of injury. While a variety of arm swing techniques was already shown in world class beach volleyball players, it is unclear if this is also true for world class indoor volleyball. Therefore, the purpose of this study was to assess the spike attack arm swing techniques of Olympic volleyball winners and finalists (1984-2021) and to investigate possible differences between sex, playing position, scoring system, and compared to beach volleyball. Eighty-two male (M) and 85 female (F) players were assessed from video recordings from ten competitions. Five different arm swing techniques in the cocking phase (Straight, Bow-and-arrow high, Bow-and-arrow low, Snap, Circular) were classified by two experts. The most frequent technique for both sexes was the Circular (M = 40.2%; F = 38.8%), followed by Snap (M = 28.0%; F = 23.5%), Bow-and-arrow low (M = 20.7%; F = 21.2%), Bow-and-arrow high (M = 7.3% F = 11.8%), and Straight (M = 3.7%; F = 4.7%). Bow-and-arrow high and Straight techniques were significantly less used than other techniques in both sexes. There were no significant differences (p &gt; 0.05) in arm swing techniques between sexes, playing positions, and scoring system but significant differences (p &lt; 0.001) to beach volleyball. Although most volleyball textbooks only describe the Bow-and-arrow techniques, most of the world class indoor volleyball players used Circular and Snap arm swing techniques. Reasons for that could be the implicit knowledge of players (and coaches) regarding increased performance (ball speed) and injury prevention. Based on these results we suggest to critically revise arm swing technique training especially for young players and players with shoulder problems.

Poster 185: Flexor Pronator Mass Contribution to Elbow Valgus Stability: A Biomechanical Project

Objectives:Identify the main muscle in the flexor pronator mass (the pronator teres (PT), flexor carpi radialis (FCR), flexor digitorum superficialis (FDS), and flexor carpi ulnaris (FCU)) that contributes most to valgus stability at a greater range of elbow motion (60-150 degrees) than in previous studies.Methods:8 cadaveric elbows in an in vitro biomechanical study were investigated. The specimens were mounted on a custom apparatus from the distal humerus to the fingers. Each muscle group of the flexor pronator mass was relatively loaded based on physiologic cross-sectional area. There were 6 loaded conditions: all loaded, unloaded PT, unloaded FCR, unloaded FDS, unloaded FCU, and all unloaded. A 2 N-m valgus torque was applied at a rate of 1 mm/sec. Valgus angle was measured for each loaded condition, especially between all loaded and one unloaded muscle. This allowed an increase in valgus angle for one unloaded muscle. The higher increase in valgus angle indicated the higher the contribution of that released muscle to valgus stability. This was performed at 60, 90, 120, and 150 degrees of elbow flexion to cover the range at which the UCL tears during the late cocking and early acceleration phases of throwing. The measurements were made in two conditions: first with the UCL intact and second with the UCL resected at the anterior bundle.Results: There was a statistical significance in the mean change in valgus angle at all flexion angles and load conditions when the UCL was intact vs when it was resected (3.76 ± 2.78 SD vs 4.82 ± 2.99 SD degrees).The valgus angle was statistically mostly increased in the “all unloaded” condition when compared to all the other loaded conditions at all flexion angles involving both when the UCL was intact and resected.Unloading one individual flexor pronator muscle did not significantly affect the valgus stability of the elbow.There was a trend towards FDS as being the primary flexor pronator stabilizer when the elbow was taken from an all-loaded condition to one muscle that was unloaded (P value = 0.169).At 150 degrees, the elbow was statistically significantly most stable compared to all the other flexion angles.At 90 degrees, the elbow was most unstable with an increase in valgus angle of 1.2 degrees between intact and resected UCL conditions.At 60 degrees with the UCL resected, there was not a statistical significant difference in valgus angle between all unloaded and unloaded FDS conditions signifying that the FDS contributed most to valgus stability. Conclusions: Physical examination of the UCL is best performed with the elbow at 90 degrees with the forearm in neutral (most unstable out of the flexion angles we tested).At 150 degrees, the elbow is most stable to valgus stress.When the UCL is injured, the FDS appeared to contribute most to valgus stability at 60 degrees out of the four flexor pronator muscles.There was a trend towards FDS as being the primary flexor pronator stabilizer.Rehabilitation of the flexor-pronator mass should focus on the FDS. Figure 1.Figure 2.Table 1.Two-group comparisons of mean valgu angle under different loading conditionsTable 2.Two-group comparisons between all unloaded condition and other loaded conditions at 60˚ elbow flexion with resected UCL.

Comparison of Shoulder Kinematics and Muscle Activation of Female Elite Handball Players With and Without Pain-An Explorative Cross-Sectional Study.

Non-traumatic shoulder injuries are common in team handball. However, many athletes continue to throw, despite pain in the shoulder. This study investigated upper body kinematics and muscle activation while throwing in female elite handball players with and without shoulder pain. Thirty female elite team handball players, 15 with pain (age 22.2 ± 2.9 yrs.) and 15 without pain (age 20.4 ± 2.6 yrs.) performed five standing throws in which joint kinematics and muscle activity were measured in the following muscles: pectoralis major, infraspinatus, serratus anterior, latissimus dorsi, and upper-, middle-, and lower trapezius. The main findings revealed that peak joint angles and angular velocities were not different between groups; however, group differences were observed in earlier timing of position and longer time spent in maximal shoulder extension and external shoulder rotation in the pain group compared with the no pain group. The pain group also revealed a significant lower muscle peak activity in the serratus anterior during the cocking phase compared to the no pain group. After the cocking phase and at ball release, the groups had similar activation. In conclusion, the present study showed group differences in appearance and time spent in maximal humerus extension and external rotation and a different serratus anterior muscle peak activity between elite handball players playing with and without shoulder pain, which are identified as possible mechanisms of adaptation to avoid pain.

Glenohumeral Internal Rotation Deficit on Pitching Biomechanics and Muscle Activity.

To characterize the scapular pitching biomechanics in symptomatic GIRD pitchers (SG) compared to asymptomatic GIRD (ASG) and healthy pitchers. The scapular kinematics and associated muscle activities during pitching were recorded in 33 high school pitchers. Compared to healthy, GIRD pitchers had less scapular posterior tilt in each pitching event (average difference, AD=14.4°, p<0.01) and ASG demonstrated less scapular upward rotation at ball release (AD=12.8°, p<0.01) and greater muscle activity in the triceps brachii in the early-cocking phase (AD=9.9%, p=0.015) and in the serratus anterior in the late-cocking phase (AD=30.8%, p<0.01). Additionally, SG had less muscular activity on triceps brachii in the acceleration phase and serratus anterior in the cocking phase (AD=37.8%, p=0.016; AD=15.5%, p<0.01, respectively) compared to ASG. GIRD pitchers exhibited less scapular posterior tilt during pitching, which may cause impingement. Since tightness of the anterior shoulder is a common cause of inadequacy of posterior tilt during arm elevation, stretching exercise of the anterior shoulder is recommended. Given the inadequate recruitment during pitching in the GIRD pitchers, symptoms may develop following potential impingement.

Beach volleyball spike arm swing techniques of Olympics and world championships winners (1996–2019) reveal gender differences

The spike attack is one of the most important skills in beach volleyball, and as an overarm movement, places significant load on the shoulder joint that could lead to increased risk of injury. An analysis of the different techniques used by elite athletes could provide important insights regarding the etiology of these injuries. This study aimed to assess the spike attack arm swing techniques of Olympics and World Championships (1996-2019) beach volleyball winners and to investigate possible gender differences. Twenty-five male and twenty female winners were assessed on video recordings from eighteen competitions. The different arm swing techniques in the cocking phase (Straight, Bow-and-arrow high, Bow-and-arrow low, Snap, and Circular) were classified by two experts. Intra-rater reliability of both experts (κ = 1.000, P &lt; .001 and κ = .969, P &lt; .001 respectively) and inter-rater reliability (κ = .969, P &lt; .001), assessed by Cohen’s Kappa, were almost perfect. There were significant gender differences in arm swing techniques ( P &lt; .001) with a large size effect (Cramer’s V = .650). The most frequent technique for men was the Bow-and-arrow low (56%) followed by Circular (24%) and Bow-and-arrow high (20%), while for women were the Bow-and-arrow high (30%) and Snap (30%), followed by Bow-and-arrow low (25%) and Straight (15%). The results showed a great variation in arm swing techniques even among world class beach volleyball players as well as significant gender differences, and could allow us to develop interesting hypotheses regarding the mechanisms that could lead to shoulder overuse injuries.

Manipulation of task constraints on throwing of amateur handball athletes

BACKGROUND: In handball, speed and accuracy are essential characteristics for the performance of throwing. AIM: To verify the effects of manipulation of task constraints during the throws on kinematic variables in amateur handball players. METHOD: 18 amateur handball players (18-27 years) made 10 throws to the target with a focus on speed and 10 throws with a focus on accuracy. The kinematic analysis of the throwing was performed, and the Student's t-test was used. RESULTS: Greater velocity, and hand, acromion, and iliac spines trajectories for throws with a focus on speed in cocking phase was observed. During the acceleration phase, there was greater velocity, and trajectory of the right upper posterior iliac spine, and less time and hand, acromion, and left upper posterior iliac spines trajectories for throws with a focus on speed. The throw with a focus on speed showed greater shoulder and elbow angles at the beginning, and greater elbow angle at the end of throwing. CONCLUSION: The manipulation in the focus of the throw influenced the movement strategy from the cocking phase to the acceleration phase according to the movement intentionality, with most of the variables presenting greater values in the throw with a focus on speed.

Upper body contributions to pitched ball velocity in elite high school pitchers using an induced velocity analysis

Interest in joint and segment contributions to pitched ball velocity has been dominated by inverse dynamic solutions, which is limited in ascertaining complex muscle/joint interactions. Our purpose was to use induced velocity analysis to investigate which joint(s) made the largest contribution to the velocity of a pitched ball. Pitching data were collected from six elite high school-aged pitchers with no history of arm injury. Participants threw a fastball pitch from the windup on flat ground. Data were collected using seven Vicon 612 cameras (250 Hz) and three AMTI force platforms (1000 Hz). A 14-segment biomechanical model (feet, legs, thighs, pelvis, a combined thorax-abdomen-head, i.e., trunk, upper arms, forearms, and hands) was implemented in Visual3D as a dynamic link library built using SD/Fast (PTC) software. Model-generated induced velocity of the ball was validated against ball velocity obtained from a calibrated radar gun. Velocity induced torques at the shoulder just prior to release, and elbow during the cocking phase, contributed 31.0% and 18.1%, respectively, to forward ball velocity. The centripetal/Coriolis effects from the upper arm and forearm velocities made the largest contribution to ball velocity (average 57.8%), but the source of these effects are unknown. The lower extremities and trunk made little direct contribution to pitched ball velocity. These results may have implications with regard to pitching performance enhancement and rehabilitation.

Evaluation and management of elbow injuries in the adolescent overhead athlete.

With an increased interest in youth sports, the burden of overhead throwing elbow injuries accompanying early single-sport focus has steadily risen. During the overhead throwing motion, valgus torque can reach and surpass Newton meters (N m) during the late cocking and early acceleration phases, which exceeds the tensile strength (22.7–33 N m) of the ulnar collateral ligament. While the ulnar collateral ligament serves as the primary valgus stabilizer between and degrees of elbow flexion, other structures about the elbow must contribute to stability during throwing. Depending on an athlete’s stage of skeletal maturity, certain patterns of injury are observed with mechanical failures resulting from increased medial laxity, lateral-sided compression, and posterior extension shearing forces. Together, these injury patterns represent a wide range of conditions that arise from valgus extension overload. The purpose of this article is to review common pathologies observed in the adolescent overhead throwing athlete in the context of functional anatomy, osseous development, and throwing mechanics. Operative and non-operative management and their associated outcomes will be discussed for these injuries.

Effect of Glenohumeral Internal Rotation Deficit on Shoulder in Baseball Pitchers during Fastball Pitching

Previous studies have reported that pitchers with glenohumeral internal rotation deficit (GIRD) may increase the risk of shoulder injury. However, limited information is available regarding the specific effects of GIRD in baseball pitching. The purpose of this study was to investigate whether baseball pitchers with GIRD change their pitching mechanism. Fifteen baseball pitchers with GIRD and 15 pitchers without GIRD were recruited from university or senior high-school teams. A three-dimensional motion analysis system (Eagle System, Motion Analysis Corporation, Santa Rosa, CA, USA) was used to capture the pitching motion while performing fastball pitches. The kinematics and kinetics of the throwing shoulder and trunk were analyzed based on motion captured data. The Mann–Whitney U test was used to test the differences of the analyzed parameters between two groups. At the instant of ball release, the GIRD group showed lower shoulder external rotation and trunk rotation, and larger shoulder horizontal adduction. In addition, the GIRD group exhibited a significantly larger shoulder inferior force in the cocking and acceleration phase, and a significantly larger internal rotation torque in the acceleration phase. The present results suggested that pitchers with GIRD need stretch training to enlarge joint range of motion, and to improve trunk strength and flexibility to alleviate potential problems associated with pitching in GIRD pitchers.

Relationship Between Kinematics, Strength, And Throwing Velocity Of Adolescent Softball Players During Overhand Throwing

The kinematics of overhand throws by adolescent softball players is currently under-reported. Identifying the relationship between kinematics, strength and velocity can help guide further research and promote better understanding of the sport. Current research has investigated the differences between softball and baseball but has not looked at how kinematics and strength correlate with throwing velocity in softball. PURPOSE: To identify the relationship between kinematics, strength, and velocity of an overhand throw in adolescent softball players. METHODS: 25 adolescent softball players performed 3 maximum effort overhand throws. The throws were filmed using a 2-D video analysis system consisting of 3 cameras set up in the frontal and sagittal planes. The velocity of the throws were recorded using a speed gun. Key positions were identified in six throwing phases and angles were measured using software on a tablet. Bilateral hip and shoulder strength of each player were measured using standardized methods via handheld dynamometer. Correlation coefficients were determined. RESULTS: A moderate and significant correlation was found between the velocity of overhand throw and the stride knee flexion angle during the arm cocking phase (r= .55, p=.004), the stance knee flexion angle during stride phase (r= .49, p= .015), and the elbow flexion angle during arm acceleration phase (r= -.45, p=.024). A moderate and significant correlation was found between trunk flexion angle during follow through phase and hip internal rotation (r= -.45, p=.04) as well as hip external rotation (r= -.53, p=.013) strength. CONCLUSION: Increases in velocity were influenced by lower extremity variables including increases in stride knee flexion angle during the arm cocking phase and increased stance knee flexion during stride phase. Upper extremity variables that related to higher velocity included decreased elbow flexion at the end of acceleration phase. Strength parameters including hip internal and external rotation strength were found to be related to higher velocities. These findings highlight the potential influence of lower extremity kinematic variables and strength on performance as measured by velocity. These results can benefit players or coaches who are teaching or learning how to do the overhand throw.