Energy Flow Analysis to Investigate Youth Pitching Velocity and Efficiency

Energy flows with intentional changes in leg movements during baseball pitching

Baseball pitchers are typically required to generate high ball velocity in their pitches. Many studies have focused on the lower extremity movements engaged at the beginning of the pitching motion to generate high ball velocity. It is assumed that the change in movement of the lower extremity induces the change in energy flow in pitching because the lower extremity generates high mechanical energy transferred to the ball. However, no studies have focused on the effects of intentional changes in lower extremity movements on energy flow. This study examined how altering stride length changes the energy flow from the lower extremities to the trunk. Twenty male college baseball pitchers participated in this study. In addition to pitching with normal stride length (NS), they pitched with under-stride length (US) and over-stride length (OS), defined as ±20% of NS. The positive and negative work of joint power, the sum of joint force power and segment torque power, were analyzed at the pivot hip, stride hip, and trunk joint. Positive work was defined as energy inflow to the lower torso from each joint, while negative work was defined as energy outflow from the lower torso to each joint. These values were then compared across stride length conditions. Our results showed that the energy inflow from the pivot hip to the lower torso and outflow from the lower torso to the stride hip changed with stride length during each phase. However, the total energy outflow from the lower torso to the trunk joint during the stride and arm-cocking phase was not significantly different with stride length (p = 0.59; η 2 = 0.02), and the ball velocity did not significantly differ between the US and OS (p = 1.00; d < 0.01). This study highlights that altering stride length might not lead to changes in total energy outflow from the lower torso to the trunk joint, implying difficulties in explaining ball velocity only by the lower extremity mechanics.

The Influence of Different Implements on Kinematics and Kinetics Compared to Men's Javelin Throw

Javelin throwers cannot safely throw with a long approach run often per training session. Therefore, implements of different shapes and masses are thrown from short run-ups to emulate the demands of achieving high throwing distances. This study examined the effects of different implements, thrown from various approaches, on the kinematics and kinetics of the throwing arm. The throwing motions of 6 athletes, each throwing 6 different implements were recorded using 12 infrared cameras. Kinematics and kinetics of the shoulder and elbow joints were calculated and statistically compared. The results show that lighter implement throws achieved higher release speeds, while heavier implements required greater work to be done on them. We identified significant differences for the shoulder external rotation angle (P < .001), the shoulder internal rotation (P = .040), and elbow extension (P = .003) angular velocities and the torques of the shoulder internal rotation (P = .006), horizontal flexion (P = .004), and the elbow varus (P = .008). It can be concluded that throws with balls of different masses have different angular velocities and joint torques, and therefore can be used to train speed and strength aspects of the javelin throw while using lower run-up speeds.

Evaluation and Preparation of the Baseball Player in the Athletic Training Room

A critical aspect of the care of the baseball player involves understanding injury patterns, workload tolerance, and objective markers that can aid in identifying predisposing factors to injury. After injury, a well-structured rehabilitation program can return many players to the field. The greatest challenge is not only returning them to the previous level of performance but also preventing reinjury and maintaining durability. Potential factors implicated in the most common injuries include deficits in range of motion, balance, core strength, lumbopelvic control, thoracic rotation, posture, and muscle imbalance. Organizing an appropriate rehabilitation program with these factors in mind is critical.

Athlete body composition influences movement during sporting tasks: an analysis of softball pitchers' joint angular velocities

Softball pitchers are often above-average size and frequently injured; therefore, it is necessary to understand how biomechanics can change according to pitcher body composition. The purpose of this study was to examine the relationship between joint peak angular velocities and pitch velocity, as well as examine how pitchers' joint angular velocities differ between high and healthy body-fat percentage (BF%) groups. Forty high-school and college softball pitchers (170.6 ± 6.3 cm, 75.5 ± 16.1 kg, 16 ± 2 years, 34.6 ± 7.4 BF%) completed body composition testing and were placed in one of two groups: 1) high-fat% (≥32%) or 2) healthy-fat% (<32%). Pitchers completed fastball trials. Kinematic data were tracked using an electromagnetic system synced with motion analysis software. Peak and times-series joint angular velocities were tracked over the final 101 frames of the pitch. Pitch velocity was significantly correlated with peak elbow flexion (r = .380, p = .016) and wrist flexion (r = .621, p < .001) angular velocity. A small difference in elbow joint angular velocity was found between body fat percentage groups between ball release and follow-through (SPM(t)1,38 = 3.296, p = .003). Peak joint angular velocities are related to pitch velocity and slight differences in movement patterns exist according to pitcher body fat percentage.

Torso kinematic patterns associated with throwing shoulder joint loading and ball velocity in Little League pitchers

The purpose of this study was to investigate the associations between kinematic patterns of the torso segment and shoulder joint loading as well as pitching performance in youth pitchers. Twenty-four Little League pitchers threw fastballs while motion capture and force plate data were collected and ball speed was measured with a radar gun. Three-dimensional torso segment kinematics (absolute angles and angular velocities) and shoulder net joint moments (NJM) and forces were calculated. The time-series kinematic data were used as inputs to a principal components analysis to extract torso movement patterns. Associations between torso movement patterns and discrete peak shoulder NJM, compressive force, and ball speed were investigated with nonparametric correlations. Torso segment motion patterns related to forward flexion, lateral flexion (away from pitching arm), and axial rotation and rotational velocities were associated with shoulder joint kinetics and ball speed. In addition, excessive axial (transverse plane) torso rotation at ball release correlated positively with shoulder joint loads but not ball speed, which may indicate the prospect for decreasing joint kinetics while maintaining pitching performance through targeted interventions. These results provide a deeper understanding about the interrelationships between torso kinematic patterns, shoulder kinetics, and pitching performance.

Whole-body energy transfer strategies during football instep kicking: implications for training practices

Knowledge of whole-body energy transfer strategies during football instep kicking can help inform empirically grounded training practices. The aim of this study was thus to investigate energy transfer strategies of 15 semi-professional players performing kicks for speed and accuracy. Three-dimensional kinematics and GRFs (both 1000 Hz) were incorporated into segment power analyses to derive energy transfers between the support leg, torso, pelvis and kick leg throughout the kick. Energy transferred from support leg (r = 0.62, P = 0.013) and torso (r = 0.54, P = 0.016) into the pelvis during tension arc formation and leg cocking was redistributed to the kick leg during the downswing (r = 0.76, P < 0.001) and were associated with faster foot velocities at ball contact. This highlights whole-body function during instep kicking. Of particular importance were: (a) regulating support leg energy absorption, (b) eccentric formation and concentric release of a 'tension arc' between the torso and kicking hip, and (c) coordinated proximal to distal sequencing of the kick leg. Resistance exercises that replicate the demands of these interactions may help develop more powerful kicking motions and varying task and/or environmental constraints might facilitate development of adaptable energy transfer strategies.

Segment power analysis of collegiate softball hitting

The primary aim of this investigation was to describe the energy flow through the kinetic chain during softball hitting using a segmental power analysis. Twenty-three NCAA Division I collegiate softball athletes (20.4 ± 1.7 yr; 166.7 ± 22.0 cm; 74.9 ± 15.9 kg) performed three maximum effort swings off a stationary tee placed in the middle of the strike zone. Pelvis, trunk, humerus, forearm and hand segment powers were integrated across four phases of the softball swing (load, stride, acceleration, and follow-through). The load and stride phases had low segment energy inflow and outflow values as well as net segment energy flow for all body segments compared to subsequent phases of the swing. The acceleration phase showed large trunk inflow values relative to the pelvis. There was also descriptively larger front compared to back-side upper extremity inflow. Finally, the follow-through phase showed primarily energy outflow for the upper extremity segments likely attributed to slowing down rotation.

Relationship Between Lumbar Locked Rotation, Trunk Rotation During Pitching, and Pitch Velocity in High School Baseball Players

Background

Trunk rotation during pitching correlates with pitching velocity and load on the joints of the upper limb. Trunk rotation is often focusing on during teaching the pitching motion. Athletes who exhibit early trunk rotation during pitching often have low thoracic spine rotational range of motion. The purpose of this study was to investigate the relationship between the range of thoracic spine rotation measured using the lumbar locked rotation test (LLR-t), hip-shoulder separation (H/S) and thoracic rotation angle at stride foot contact (SFC), and ball velocity.

Study design

Descriptive laboratory study.

Methods

Fifteen healthy male high school students belonging to a baseball club were recruited for participation. The throwing side and non-throwing side LLR-t was performed using an inclinometer. Hip-shoulder separation and thoracic rotation angle during SFC were measured using a pitching motion analysis application: Pitch AI. In addition, a tracking device specifically designed for pitching：Pitching2.0 was employed to measure ball velocity. Correlations between LLR angle, H/S, trunk rotation angles at SFC, and ball velocity were examined using Pearson's correlation coefficient.

Result

There was a positive correlation（r=0.52，p=0.047） between the LLRt angle and H/S. Additionally, there was a negative correlation（r=-0.62, p =0.01） between the LLRt angle on the throwing side and thoracic rotation angle. There was a positive correlation(r=0.54, p=0.04) between ball velocity and H/S and a negative correlation(r=-0.56, p=0.03) between ball velocity and thoracic rotation angle during SFC. 　.

Conclusion

The LLR-t measures thoracic rotation angle with the pelvis-lumbar spine fixed. The results indicated that throwing side LLR was related to the thoracic angle during SFC and hip-shoulder separation.

Level of evidence

3.

Predicting the Presence of Pain in Youth Baseball Pitchers Using the Concept of Biomechanical Efficiency

Background

Increases in peak shoulder distraction force and peak elbow valgus torque may influence throwing-arm pain and injury risk in youth pitchers.

Purpose/Hypothesis

The purpose of this study was to determine whether shoulder distraction force and elbow valgus torque while accounting for anthropometrics and pitch velocity can predict the presence of pain in youth baseball pitchers. It was hypothesized that throwing-arm pain could be predicted using the concept of biomechanical efficiency, where a pitcher who is less efficient (having higher force or torque with the same pitch velocity) is more likely to experience pain.

Study Design

Descriptive laboratory study.

Methods

A total of 38 youth baseball pitchers (mean age, 13.3 ± 1.7 years) were divided into a pain group and pain-free group based on presence of throwing-arm pain as reported on a health history questionnaire. Each pitcher threw 3 maximal-effort fastballs to a catcher at regulation distance, and kinematics were measured using an electromagnetic motion-capture system (minimum 100 Hz). Height and weight as well as mean peak shoulder distraction force, peak elbow valgus torque, and pitch velocity across the 3 trials were evaluated. Logistic regression analyses determined whether shoulder distraction force or elbow valgus torque could predict the presence of throwing-arm pain when holding anthropometrics (body weight for shoulder distraction force; body weight and height for elbow valgus torque) and pitch velocity constant.

Results

Shoulder distraction force significantly predicted the presence of throwing-arm pain after accounting for body weight and pitch velocity (χ2 = 9.49; P = .023). Specifically, for every 1-N increase in peak shoulder distraction force while holding body weight and pitch velocity constant, there was a 0.6% increased likelihood of experiencing throwing-arm pain. Elbow valgus torque could not predict the presence of pain when holding body weight, height, and pitch velocity constant.

Conclusion

The models demonstrated that increases in peak shoulder distraction forces when holding pitch velocity and body weight constant increased a youth baseball pitcher's likelihood of experiencing throwing-arm pain. The study results support the concept of the biomechanical efficiency framework by offering evidence that maintaining pitch velocity with a lower joint load led to a lower likelihood of pain.

Clinical Relevance

Results suggest that practicing efficient movement strategies can decrease the likelihood of experiencing throwing-arm pain while maintaining performance.

How the acceleration phase influences energy flow and the resulting joint moments of the throwing shoulder in the deceleration phase of the javelin throw

Introduction

The throwing motion in the javelin throw applies high loads to the musculoskeletal system of the shoulder, both in the acceleration and deceleration phases. While the loads occurring during the acceleration phase and their relationship to kinematics and energy flow have been relatively well investigated, there is a lack of studies focusing the deceleration phase. Therefore, the aim of this study is to investigate how the throwing arm is brought to rest, which resultant joint torques are placed on the shoulder and how they are influenced by the kinematics of the acceleration phase.

Methods

The throwing movement of 10 javelin throwers were recorded using a 12-infrared camera system recording at 300 Hz and 16 markers placed on the body. Joint kinematics, kinetics and energy flow were calculated between the touchdown of the rear leg and the timepoint of maximum internal rotation after release +0.1 s. Elastic net regularization regression was used to predict the joint loads in the deceleration phase using the kinematics and energy flow of the acceleration phase.

Results

The results show that a significant amount of energy is transferred back to the proximal segments, while a smaller amount of energy is absorbed. Furthermore, relationships between the kinematics and the energy flow in the acceleration phase and the loads placed on the shoulder joint in the deceleration phase, based on the elastic net regularized regression, could be established.

Discussion

The results indicate that the loads of the deceleration phase placed on the shoulder can be influenced by the kinematics of the acceleration phase. For example, an additional upper body forward tilt can help to increase the braking distance of the arm and thus contribute to a reduced joint load. Furthermore, the energy flow of the acceleration phase can be linked to joint stress. However, as previously demonstrated the generation of mechanical energy at the shoulder seems to have a negative effect on shoulder loading while the transfer can help optimize the stress. The results therefore show initial potential for optimizing movement, to reduce strain and improve injury prevention in the deceleration phase.

Energy generation, absorption, and transfer at the shoulder and elbow in youth baseball pitchers

Performance during the baseball pitch is dependent on the flow of mechanical energy through the kinetic chain. Little is known about energy flow during the pitching motion and it is not known whether patterns of energy flow are related to pitching performance and injury risk. Therefore, the purpose of this study was to quantify energy generation, absorption, and transfer across the shoulder and elbow during the baseball pitch and explore the associations between these energetic measures, pitch speed, and traditional measures of upper extremity joint loading. The kinematics of 40 youth baseball pitchers were measured in a controlled laboratory setting. Energy flow between the thorax, humerus, and forearm was calculated using a segmental power analysis. Regression analyses revealed that pitch speed was best predicted by arm cocking phase shoulder energy transfer to the humerus and peak elbow valgus torque was best predicted by arm acceleration-phase elbow energy transfer to the forearm. Additionally, energy transfer across the shoulder and elbow generally exhibited the strongest correlations to pitch speed and upper extremity joint loads. These data reinforce the importance of energy transfer through the kinetic chain for producing high pitch speeds and provide descriptive data for energy flow during baseball pitching not previously found in the literature.

Countermovement Jump and Momentum Generation Associations to Fastball Velocity Performance Among Division I Collegiate Pitchers

ABSTRACT

Sakurai, M, Qiao, M, Szymanski, DJ, and Crotin, RL. Countermovement jump and momentum generation associations to fastball velocity performance among Division I collegiate pitchers. J Strength Cond Res 38(7): 1288-1294, 2024-The current study explored the relationships between countermovement jump (CMJ) profiles and baseball pitching performance. Nineteen Division I collegiate pitchers performed in-laboratory pitching and bilateral CMJs. Whole-body kinematics and ground reaction force were collected during both pitching and CMJ evaluations. Statistically significant correlations of concentric impulse and peak power in the CMJ test with fastball velocity were observed (r = 0.71 and 0.68). Concentric impulse in CMJ also showed a statistically significant correlation with linear momentum in the anterior-posterior direction during pitching (r = 0.68). Lean body mass and body mass showed statistically significant correlations with both of the 2 linear momentums during pitching (r = 0.71∼0.83), and concentric impulse in CMJ (r = 0.71 and 0.81). Pelvis and trunk pitching mechanics did not correlate with any of the CMJ variables at the statistically significant level, whereas the direction of the correlations varied (|r| < 0.45). Assessment of a baseball pitcher's CMJ should focus on concentric impulse and peak power because only these showed meaningful relationships with fastball velocity or momentum generation during pitching. An increase in lean body mass is also suggested to be able to generate more impulse and momentum. Baseball coaches, strength coaches, and clinicians are encouraged to include lower-body explosive training to enhance the force and power output capacity of baseball pitchers.

Does Deep Squat Quality Affect the Propulsion of Baseball Throwing?

This study investigates the influence of the quality of the "deep squat" movement, adapted from the Functional Movement Screen (FMS) system, on the lower extremity movement pattern during baseball throwing, and its potential impact on throwing performance and propulsion efficiency. Twenty-two baseball players were recruited and categorized into two groups: 13 in the high-score squat group (HSS) and 9 in the low-score squat group (LSS), based on their deep squat screening results. This research explored disparities in ball velocity, propulsion efficiency, propulsion ground reaction force (GRF) characteristics, and throwing kinematics between these two groups. The findings revealed no significant difference in ball velocity between the groups. However, the LSS group demonstrated a lower propulsion GRF efficiency (p < 0.030, ES = 0.46), along with a higher vertical peak GRF (p < 0.002, ES = 0.66). In the pivot leg, the HSS group exhibited significantly lower impulse forces in the Impulse Fresultant (p < 0.035, ES = 0.45), throwing direction (p < 0.049, ES = 0.42), and vertical direction (p < 0.048, ES = 0.42). Additionally, the contribution to the ball velocity of the pivot leg was significantly greater in the HSS group, along with significantly better efficiency in Impulse Fresultant (p < 0.035, ES = 0.45), throwing direction (p < 0.053, ES = 0.41), and vertical direction (p < 0.032, ES = 0.46). In the leading leg, the HSS group demonstrated significantly lower impulse forces in the Impulse Fresultant (p < 0.001, ES = 0.69), throwing direction (p < 0.007, ES = 0.58), and vertical direction (p < 0.001, ES = 0.70). Moreover, the contribution to the ball velocity of the leading leg was significantly greater in the HSS group, accompanied by significantly better efficiency in Impulse Fresultant (p < 0.003, ES = 0.63), throwing direction (p < 0.005, ES = 0.60), and vertical direction (p < 0.021, ES = 0.49). In conclusion, this study suggests that squat screening is a valuable tool for assessing propulsion efficiency. Coaches and trainers should be mindful of players with low squat quality but high throwing performance, as they may face increased impact and injury risks in the future.

The influence of body segment estimation methods on body segment inertia parameters and joint moments in javelin throwing

Calculated intersegmental moments are commonly used in analyzing throwing movements. The inverse dynamics (ID) results can vary due to the chosen set of body segment inertia parameters (BSIP). A multitude of methods to determine BSIP sets are available. The purpose of this study was to clarify the influence of different estimation methods on the BSIPs and the respective impact on the ID results in javelin throwing. Movement kinematics were recorded for ten male javelin throwers. Six different methods were used to estimate BSIP sets for the upper extremities of each thrower. Subsequently, ID results were obtained for each thrower and BSIP set. Results show variations between 8% and 120% between the BSIP sets, and maximum intersegmental moments varied between 6% and 21%, respectively. Joint-specific variations of intersegmental moments were observed as well as movement-specific variations within a joint related to the different BSIP sets. Furthermore, the influence of BSIP sets appears to be subject-specific as well, with observed variations between 9% and 18% - some athletes are better represented by the chosen methods than others. Hence, our study results suggest that the method to determine BSIP sets needs to be carefully chosen for calculating joint kinetics in throwing movements.

Energy flow in men's javelin throw and its relationship to joint load and performance

Background

Performance in javelin throwing is dependent on the release speed and therefore the energy transferred to the javelin. Little is known about the flow of mechanical energy in javelin throwing and whether there is a connection to joint loading and throwing performance. The purpose of the study was therefore to investigate (1) the energy flow within the kinetic chain of the throwing arm, (2) how it is related to performance and joint loads and (3) how joint forces and torques are used to transfer, generate and absorb mechanical energy.

Methods

The kinematics of 10 experienced javelin throwers were recorded using a 12-camera infrared system. 16 markers were placed on the athlete's body, five on the javelin to track the movement of each segment. A segmental power analysis was carried out to calculate energy flow between upper body, upper arm, forearm and hand. Stepwise regression analysis was used to calculate the variable that best predicts release speed and joint loads.

Results

The results indicate that the higher the peak rate of energy transfer from the thorax to the humerus, the higher the release speed and the joint loads. While there were no differences between the peak rate of energy transfer in the different joints, the energy transferred differed depending on whether joint forces or torques were used. It can be further shown that higher joint torques and thus higher rotational kinetics at the shoulder are linked to higher release speeds. Thus, the movements of the upper body can be of great influence on the result in javelin throwing. Furthermore, the data show that athletes who are able to transfer more energy through the shoulder, rather than generate it, experience a smaller joint loading. An effective technique for improved energy transfer can thus help perform at the same level while lowering joint stress or have higher performance at the same joint loading.

Exploratory Investigation Into the Impact of Bilateral and Unilateral Jump Characteristics on Ground Reaction Force Applications in Baseball Pitching

ABSTRACT

Lis, R, Szymanski, DJ, Qiao, M, and Crotin, RL. An exploratory investigation into the impact of bilateral and unilateral jump characteristics on ground reaction force applications in baseball pitching. J Strength Cond Res 37(9): 1852-1859, 2023-Jump tests are effective, valid, and reliable in examining lower-body power that can influence ground reaction forces (GRFs) in baseball pitching. Relationships between drive and stride leg GRFs and fastball velocities while pitching from the wind-up and stretch were evaluated for performance influences across the following conditions: (a) lower-body GRFs from unilateral countermovement jumps (UCMJ) and bilateral countermovement jumps (BCMJ) and (b) BCMJ and drive and stride leg UCMJ height. Nineteen Division I collegiate baseball pitchers (age; 19.9 ± 1.5 years, height; 1.86 ± 0.06 m, body mass; 90.7 ± 13.8 kg) completed BCMJ and UCMJ tests and threw four-seam fastballs from a pitching mound with 2 embedded force plates. Three moderate associations ( r ≥ 0.47) were statistically significant ( p < 0.05) for BCMJ and UCMJ heights to pitching GRFs. Stride leg UCMJ height was significantly greater than drive leg UCMJ height, p < 0.01, η 2 = 0.34. Wind-up and stretch GRFs were statistically similar. Fastball velocities showed a statistically significant association that was moderately high with wind-up and stretch stride leg anterior-posterior GRFs ( r ≥ 0.65, p < 0.01). Collegiate pitchers jumped significantly higher with their stride leg, and the sum of vertical unilateral jump height of both legs was significantly greater (27%) than BCMJ height to indicate greater single-leg dominance in jumping. Although stride leg height was higher, improving stride leg jumping performance may be functionally more important in producing greater momentum into foot strike that has the potential to increase fastball velocity.

Hip Strength and Pitching Biomechanics in Adolescent Baseball Pitchers

CONTEXT

Hip strength may influence the energy flow through the kinematic chain during baseball pitching, affecting athlete performance as well as the risk for injury.

OBJECTIVE

To identify associations between hip strength and pitching biomechanics in adolescent baseball pitchers during 3 key events of the pitching cycle.

DESIGN

Cross-sectional study.

SETTING

Biomechanics laboratory.

PATIENTS OR OTHER PARTICIPANTS

A total of 26 adolescent male baseball pitchers (age = 16.1 ± 0.8 years, height = 184.29 ± 5.5 cm, mass = 77.5 ± 8.5 kg).

MAIN OUTCOME MEASURE(S)

The main outcome measure was hip strength (external rotation, internal rotation, flexion, abduction, adduction, and extension). After strength measurements were acquired, motion capture was used to obtain a full-body biomechanical analysis at 3 events during the pitching cycle (foot contact, maximal external rotation, and ball release). We then evaluated these values for associations between hip strength and pitching biomechanics. Scatterplots were examined for linearity to identify an appropriate correlation test. The associations were linear; thus, 2-tailed Pearson correlation coefficients were used to determine correlations between biomechanical metrics. An α level of .01 was chosen.

RESULTS

Ten strong correlations were found between pitching biomechanics and hip strength: 8 correlations between hip strength and kinematics at key points during the pitch and 2 correlations of hip strength with peak elbow-varus torque.

CONCLUSIONS

Several correlations were noted between lower extremity strength and pitching biomechanics. This information provides data that may be used to improve performance or reduce injury (or both) in pitchers. Increased hip strength in adolescent pitchers may both improve performance and decrease the risk of injury.

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

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.

Energy flow through the lower extremities in high school baseball pitching

It is generally accepted that most of the energy transferred to the ball during a baseball pitch is generated in the trunk and lower extremities. Therefore, purpose of this study was to assess the energy flow through the lower extremities during a baseball pitch. It was hypothesised that the (stabilising) leading leg mainly transfers energy in a distal-to-proximal order as a kinetic chain while the (driving) trailing leg generates most energy, primarily at the hip. A joint power analysis was used to determine the rates of energy (power) transfer and generation in the ankles, knees, hips and lumbosacral joint (L5-S1) for 22 youth pitchers. Analyses showed that the leading leg mainly transfers energy upwards in a distal-to-proximal order just before stride foot contact. Furthermore, energy generation was higher in the trailing leg and primarily arose from the trailing hip. In conclusion, the legs contribute differently to the energy flow where the leading leg acts as an initial kinetic chain component and the trailing leg drives the pitch by generating energy. The actions of both legs are combined in the pelvis and passed on to the subsequent, more commonly discussed, open kinetic chain starting at L5-S1.

Determinants of Biomechanical Efficiency in Collegiate and Professional Baseball Pitchers

BACKGROUND

Biomechanical efficiency, defined as fastball velocity per unit of normalized elbow varus torque, is a relatively new metric applied to improving the performance and health of baseball pitching.

PURPOSE/HYPOTHESIS

The purpose of this work was to evaluate kinematic parameters influencing biomechanical efficiency among professional and collegiate pitchers. Kinematic differences were compared between pitchers of high and low biomechanical efficiency. We hypothesized that professional pitchers would have greater biomechanical efficiency than collegiate pitchers.

STUDY DESIGN

Descriptive laboratory study.

METHODS

A deidentified biomechanical database of 545 pitchers (447 professional, 98 collegiate) was analyzed. A multivariate linear regression model was used to evaluate significant findings a priori with α = .05. Additionally, biomechanical differences were identified between competition levels and between high and low biomechanical efficiency groups using Mann-Whitney U test (α = .05).

RESULTS

Competition level and 11 (of 21) kinematic variables explained 27% of the variance in biomechanical efficiency, with most of the predictors being throwing arm kinematics (elbow flexion at stride foot contact [SFC]: β, -1.47; SE, 0.26; shoulder abduction at SFC: β, -1.78; SE, 0.39; shoulder external rotation at SFC: β, 0.60; SE, 0.22; maximum external rotation [MER] angle: β, 1.82; SE, 0.42; shoulder horizontal adduction at MER: β, -3.42; SE, 0.71) (all P≤ .05). Professional pitchers had greater biomechanical efficiency than collegiate pitchers (711.0 ± 101.0 vs 657.0 ± 99.3, respectively; P < .001; d = 0.53). Compared with the low-efficiency group, the high-efficiency group had significantly lower normalized elbow varus torque with greater weight and height (high: 0.047 ± 0.004 %wt*ht vs. low: 0.063 ± 0.006 %wt*ht, P <.001; d = 3.20). At the instant of SFC, the high-efficiency group demonstrated greater shoulder external rotation and less elbow flexion, shoulder abduction, and pelvic rotation. The high-efficiency group also had greater MER and less shoulder horizontal adduction at MER, trunk side tilt at ball release, and knee excursion from foot contact to ball release.

CONCLUSION

Professional pitchers had greater biomechanical efficiency than collegiate pitchers. Biomechanical efficiency was also affected by 11 kinematic variables identified in this study. Pitchers with higher efficiency had distinct differences in arm position, trunk side tilt, and lead-knee extension range of motion in the delivery. Thus, pitchers and baseball organizations should focus on these factors to lower normalized elbow varus torque relative to ball velocity.

Lower body energy generation, absorption, and transfer in youth baseball pitchers

An efficient baseball pitch will produce a high-velocity ball while minimizing the risk of injury to the pitcher. This study quantified ground reaction forces and lower body power during the entire pitching motion of youth baseball pitchers to investigate how developing athletes generate and transfer energy from lower limbs to the throwing arm. These data provide a foundation for comparing youth pitching strategy and mechanics to optimal throwing mechanics and may aid in developing appropriate training suggestions for this age group. Full-body three-dimensional (3D) motion capture and force platform data were collected on 23 youth pitchers performing fastballs thrown for strikes. Youth pitchers within this study used a “controlled drop” strategy in which the COM was lowered during the stride phase followed by a weak forward drive motion. Ground reaction forces (GRFs) indicate that the drive leg propels the center of mass (COM) toward the home plate while the stride leg braking force contributes to power generation up the kinetic chain. The stride hip generates energy assisting in energy flow up the kinetic chain as well as the creation of a stable base to rotate the trunk about. The lumbosacral joint generates the most energy of any joint studied, facilitating energy flow up the kinetic chain and underscoring the importance of core strength and coordination in proper pitching mechanics.

Pelvis and Trunk Energy Flow in Collegiate Softball Pitchers With and Without Upper Extremity Pain

BACKGROUND

The softball pitch is a full-body motion, where efficient proximal to distal energy flow through the kinetic chain is said to reduce stress at the upper extremity. Although altered trunk kinematic parameters are associated with upper extremity pain in softball pitchers, further research is needed to determine whether differences exist in proximal energy flow between softball pitchers with and without pain.

HYPOTHESIS/PURPOSE

To examine pelvis and trunk energy flow during the acceleration phase of the pitch in collegiate softball pitchers with and without upper extremity pain. It was hypothesized that those with upper extremity pain would have less energy flowing into the proximal ends of the pelvis and trunk as well as less energy flowing out of the distal ends of the pelvis and trunk during the acceleration phase when compared with pitchers who did not have upper extremity pain.

STUDY DESIGN

Descriptive laboratory study.

METHODS

A total of 54 female National Collegiate Athletic Association Division I softball pitchers (age, 20.2 ± 2.0 years; height, 173.5 ± 6.9 cm; weight, 78.5 ± 11.5 kg) were assigned to pain (n = 17) and pain-free (n = 38) groups. Participants pitched 3 maximal effort rise-balls for a strike, and the average of the 3 trials was used for analysis. Kinematic data were collected at 100 Hz using an electromagnetic tracking system. A segment power analysis was performed to quantify energy flow for the pelvis and trunk. The Mann-Whitney U test was used to compare pelvis and trunk energy flow during the acceleration phase of the pitch as well as pitch velocity between collegiate softball pitchers with and without upper extremity pain.

RESULTS

No significant differences were found between pelvis and trunk energy flow during the acceleration phase or pitch velocity between collegiate softball pitchers with and without upper extremity pain (all P values >.057).

CONCLUSION

Previous research determined that kinematic parameters differ between collegiate pitchers with and without upper extremity pain. However, the current study found no difference in pelvis and trunk energy flow or pitch velocity. Although altered kinematics in collegiate pitchers with upper extremity pain may serve as compensation patterns to maintain pitch velocity and proximal energy flow, future research is needed to confirm this postulation.

CLINICAL RELEVANCE

The lack of energy flow differences between upper extremity pain groups suggests that pitchers may adapt their biomechanics to maintain trunk and pelvis energy flow patterns. Coaches, athletes, and clinicians should know that movement adaptations can allow for maintained performance levels but may result in the presence of pain that may manifest in other deleterious and injury-susceptible biomechanics.

Machine Learning and Statistical Prediction of Pitching Arm Kinetics

BACKGROUND

Over the past decade, research has attempted to elucidate the cause of throwing-related injuries in the baseball athlete. However, when considering the entire kinetic chain, full body mechanics, and pitching cycle sequencing, there are hundreds of variables that could influence throwing arm health, and there is a lack of quality investigations evaluating the relationship and influence of multiple variables on arm stress.

PURPOSE

To identify which variables have the most influence on elbow valgus torque and shoulder distraction force using a statistical model and a machine learning approach.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

A retrospective review was performed on baseball pitchers who underwent biomechanical evaluation at the university biomechanics laboratory. Regression models and 4 machine learning models were created for both elbow valgus torque and shoulder distraction force. All models utilized the same predictor variables, which included pitch velocity and 17 pitching mechanics.

RESULTS

The analysis included a total of 168 high school and collegiate pitchers with a mean age of 16.7 years (SD, 3.2 years) and BMI of 24.4 (SD, 1.2). For both elbow valgus torque and shoulder distraction force, the gradient boosting machine models demonstrated the smallest root mean square errors and the most precise calibrations compared with all other models. The gradient boosting model for elbow valgus torque reported the highest influence for pitch velocity (relative influence, 28.4), with 5 mechanical variables also having significant influence. The gradient boosting model for shoulder distraction force reported the highest influence for pitch velocity (relative influence, 20.4), with 6 mechanical variables also having significant influence.

CONCLUSION

The gradient boosting machine learning model demonstrated the best overall predictive performance for both elbow valgus torque and shoulder distraction force. Pitch velocity was the most influential variable in both models. However, both models also revealed that pitching mechanics, including maximum humeral rotation velocity, shoulder abduction at foot strike, and maximum shoulder external rotation, significantly influenced both elbow and shoulder stress.

CLINICAL RELEVANCE

The results of this study can be used to inform players, coaches, and clinicians on specific mechanical variables that may be optimized to mitigate elbow or shoulder stress that could lead to throwing-related injury.

Lead Foot Progression Angle in Baseball Pitchers: Implications to Ball Velocity and Upper-Extremity Joint Moments

The instant of foot contact is an important transition point during the pitch cycle between the linear portion of the pitch, as a pitcher strides down the mound and the rotational portion of the pitch. Understanding the implications of lead foot angle at foot contact is an essential information needed to assist pitching coaches in their work with individual pitchers. Therefore, the purpose of this study was to determine the association between lead foot progression angle at foot contact and ball velocity, elbow varus moment, and pelvic rotation. Kinematic and kinetic data were collected from 99 collegiate pitchers and analyzed using a random intercept, mixed-effects regression model. Significant associations were found between lead foot progression angle at foot contact and elbow varus moment (P = .004), as well as pelvic rotation throughout the pitching motion (P < .001). The data indicate that increased lead foot internal rotation at foot contact is associated with increases in the elbow varus moment but is not associated with ball velocity. This study provides scientific evidence that the rotational positioning of the lead foot can affect both pelvic motion and upper-extremity joint moments.

Relationship between ground reaction force and throwing arm kinetics in high school and collegiate pitchers

BACKGROUND

Throwing a baseball requires the transmission of forces generated in the lower extremity, through the trunk, to the upper extremity, and ultimately translates to the ball. A disruption in the functioning of the lower extremities could lead to altered upper extremity kinematics and increased load exerted on the shoulder and elbow. The purpose of this study was to examine the relationship of ground reaction forces (GRF) on the drive and stride sides and kinetics of the throwing arm in high school and collegiate baseball pitchers.

METHODS

In this retrospective cross-sectional study, data that were previously collected during a pitching evaluation were analyzed. Fifty high school pitchers and twenty six collegiate pitchers had received a pitching evaluation. Multiple regression analysis was used to examine the relationships between variables.

RESULTS

Only the drive leg medial force was determined to be a significant predictor of maximum shoulder external rotation torque. Maximum elbow valgus torque was not correlated with any GRF variables and ball speed was only weakly correlated with stride leg medial force. There were no significant differences in GRFs between the high school and college pitchers.

CONCLUSIONS

Due to the limited relationships present, other factors such as muscle strength, coordination, kinematics, or stride technique may overshadow the effects of GRF in highly skilled pitchers and warrant further investigation. Understanding this relationship will be important to both enhancing performance and avoiding injury.

Association of Pitch Timing and Throwing Arm Kinetics in High School and Professional Pitchers

BACKGROUND

Understanding the relationship between the temporal phases of the baseball pitch and subsequent joint loading may improve our understanding of optimal pitching mechanics and contribute to injury prevention in baseball pitchers.

PURPOSE

To investigate the temporal phases of the pitching motion and their associations with ball velocity and throwing arm kinetics in high school (HS) and professional (PRO) baseball pitchers.

STUDY DESIGN

Descriptive laboratory study.

METHODS

PRO (n = 317) and HS (n = 54) baseball pitchers were evaluated throwing 8 to 12 fastball pitches using 3-dimensional motion capture (480 Hz). Four distinct phases of the pitching motion were evaluated based on timing of angular velocities: (1) Foot-Pelvis, (2) Pelvis-Torso, (3) Torso-Elbow, and (4) Elbow-Ball. Peak elbow varus torque, shoulder internal rotation torque, and shoulder distraction force were also calculated and compared between playing levels using 2-sample t tests. Linear mixed-effect models with compound symmetry covariance structures were used to correlate pitch velocity and throwing arm kinetics with the distinct temporal phases of the pitching motion.

RESULTS

PRO pitchers had greater weight and height, and faster ball velocities than HS pitchers (P < .001). There was no difference in total pitch time between groups (P = .670). PRO pitchers spent less time in the Foot-Pelvis (P = .010) and more time in the Pelvis-Torso (P < .001) phase comparatively. Shorter time spent in the earlier phases of the pitching motion was significantly associated with greater ball velocity for both PRO and HS pitchers (Foot-Pelvis: B = -6.4 and B = -11.06, respectively; Pelvis-Torso: B = -6.4 and B = -11.4, respectively), while also associated with increased shoulder proximal force (Pelvis-Torso: B = -76.4 and B = -77.5, respectively). Decreased time in the Elbow-Ball phase correlated with greater shoulder proximal force for both cohorts (B = -1150 and B = -645, respectively) with no significant correlation found for ball velocity.

CONCLUSION

Significant differences in temporal phases exist between PRO and HS pitchers. For all pitchers, increased time spent in the final phase of the pitching motion has the potential to decrease shoulder distraction force with no significant loss in ball velocity.

CLINICAL RELEVANCE

Identifying risk factors for increased shoulder and elbow kinetics, acting as a surrogate for loading at the respective joints, has potential implications in injury prevention.

Relationships between Hip Flexibility and Pitching Biomechanics in Adolescent Baseball Pitchers

CONTEXT

Inadequate hip active range of motion (AROM) may stifle the energy flow through the kinematic chain and decrease pitching performance while increasing the risk for pitcher injury.

OBJECTIVE

To examine the relationship of hip AROM and pitching biomechanics during a fastball pitch in adolescent baseball pitchers.

DESIGN

Cross-Sectional study.

SETTING

Biomechanics laboratory.

PARTICIPANTS

A voluntary sample of 21 adolescent baseball pitchers (16.1 ± 0.8 yrs.; 183.9 ± 5.2 cm; 77.9 ± 8.3 kg). Main Outcome Measure (s): Bilateral hip internal rotation (IR), external rotation (ER), flexion, extension, and abduction AROM were measured. Three-dimensional biomechanics were assessed as participants threw from an indoor pitching mound to a strike zone net at regulation distance. Pearson correlation coefficients were used to determine correlations between hip AROM and biomechanical metrics.

RESULTS

Statistically significant negative correlations were found at foot contact between back hip ER AROM and back hip abduction angle (p=0.030, r=-0.474), back hip ER AROM and torso rotation angle (p=0.032, r=-0.468),and back hip abduction AROM and lead hip abduction angle (p=0.037, r=-0.458). Back hip extension AROM was positively correlated with increased stride length (p=0.043, r=0.446). Lead hip abduction AROM was also positively correlated with normalized elbow varus torque (p=0.034, r=0.464).

CONCLUSIONS

There were several relationships between hip AROM and biomechanical variables during the pitching motion. The findings support the influence hip AROM can have on pitching biomechanics. Overall, greater movement at the hips allows for the kinematic chain to work at its maximal efficiency, increasing pitch velocity potential.

Ankle dorsiflexion deficit in the back leg is a risk factor for shoulder and elbow injuries in young baseball players

The relationship between ankle joint function and throwing-related injuries has not been demonstrated. We hypothesized that limited ankle joint range of motion (ROM) was related to risk factors for shoulder and elbow injuries in young baseball players. This 12-month prospective cohort study evaluated the age, height, weight, playing position, shoulder, elbow, and ankle function of 228 enrolled baseball players. Shoulder and elbow injuries were tracked during the season. Univariate and multivariate analyses were performed to identify risk factors for shoulder and elbow injuries among participants divided into non-injured and injured groups. Univariate analysis showed that age, height, weight, ROM of elbow flexion in the dominant arm, muscle strength ratio of shoulder abduction, and the likelihood of being a pitcher or a catcher were significantly greater in the injured group than in the non-injured group. ROM of shoulder abduction-external/internal rotation, shoulder total arc on the dominant arm, ankle joint dorsiflexion, and plantar flexion on the back (non-lead) and front (lead) legs were significantly less in the injured group than in the non-injured group. In conclusion, ROM dorsiflexion deficits in the back leg, shoulder abduction-external rotation in the dominant arm, ROM increase in elbow flexion on the dominant side, older age, and being a pitcher were significant independent risk factors for injury.

Hip Range of Motion and Strength and Energy Flow During Windmill Softball Pitching

CONTEXT

Inadequate hip range of motion (ROM) and isometric strength (ISO) may interfere with energy flow through the kinetic chain and result in increased injury susceptibility.

OBJECTIVE

To examine the relationship of hip ROM and ISO with energy flow through the trunk and pitching-arm segments during the windmill softball pitch in youth athletes. A subsequent purpose was to examine the relationship between energy flow and pitch speed.

DESIGN

Descriptive laboratory study.

SETTING

University research laboratory.

PATIENTS OR OTHER PARTICIPANTS

A sample of 29 youth softball pitchers (age = 11.2 ± 1.3 years, height = 155.0 ± 10.4 cm, mass = 53.2 ± 12.6 kg).

MAIN OUTCOME MEASURE(S)

Bilateral hip internal-rotation and external-rotation (ER) ROM and ISO were measured. Net energy outflow and peak rates of energy outflow from the distal ends of the trunk, humerus, and forearm were calculated for the acceleration phase of the windmill softball pitch, and pitch speed was measured.

RESULTS

Regression analysis revealed an effect of drive-hip ER ISO on the net energy flow out of the distal ends of the trunk (P = .045) and humerus (P = .002). Specifically, increased drive-hip ER ISO was associated with increased net energy outflow from the trunk to the humerus and from the humerus to the forearm. No significant effects of hip ROM or other hip ISO measures were observed. Additionally, pitchers who achieved higher peak rates of distal outflow tended to achieve higher pitch speeds.

CONCLUSIONS

An association was present between drive-hip ER ISO and the net energy flow out of the distal ends of the trunk and humerus during the acceleration phase of the windmill softball pitch, emphasizing the importance of hip and lower body strength in executing the whole-body windmill pitch. Overall, energy-flow analysis is an interesting new way to analyze pitching mechanics and will aid in furthering our understanding of performance and injury risk in windmill softball pitching.

Kinematic Sequence Classification and the Relationship to Pitching Limb Torques

PURPOSE

The kinematic sequence (KS) during a baseball pitch provides insight into an athlete's ability to efficiently transfer energy and develop segmental velocities, to assess the quality of body segment position and control. Study purposes were 1) to introduce the four-category Kinematic Sequence Classification System and 2) to compare elbow and shoulder torques and shoulder distraction force across the KS categories performed during the fastball pitch.

METHODS

Thirty baseball pitchers (20.0 ± 3.1 yr) underwent 3D biomechanical pitch analyses of 249 fastball pitches. Seventeen distinct KS patterns were identified and assigned into four categories: 1) The proximal-to-distal (PDS) group includes the KS closest to theoretical ideal order of the five body segments (pelvis → trunk → arm → forearm → hand). The other categories were defined based on the segment where the first out-of-sequence peak angular velocity occurred: 2) distal upper extremity (DUE), 3) proximal upper extremity, and 4) pelvis/trunk. Throwing limb shoulder distraction force and shoulder and elbow torques were calculated. Linear mixed model analyses compared variables across KS categories.

RESULTS

Average elbow valgus torques differed significantly across all categories, P = 0.023, and were greater for the DUE (73.99 ± 20.84 N·m) than the PDS (61.35 ± 16.79 N·m), P = 0.006. Shoulder external rotation torques were significantly different, P = 0.033, across categories.

CONCLUSION

The PDS group demonstrated less mechanical stresses on the throwing shoulder and elbow but was observed in only 12% of pitches. The DUE group was the most common and generated the greatest elbow valgus and shoulder external rotation torques. The KS can inform coaches and sports medicine clinicians where the greatest torques are incurred by a pitcher. A KS classification system may serve as a screening tool or target pitching instruction for injury avoidance.

Relationship Between Humeral Energy Flow During the Baseball Pitch and Glenohumeral Stability

Researchers suggest that motion deriving energy from the more proximal segments of the body is important to reduce injury susceptibility. However, limited clinical assessments have been associated with efficient energy flow within a complex movement such as the baseball pitch. This research aimed to determine the relationship between glenohumeral stability as determined by the closed kinetic chain upper extremity stability test and energy transfer into and out of the humerus during the baseball pitching motion. Kinematic and kinetic data were collected at 240 Hz on twenty-four baseball pitchers. Participants performed the closed kinetic chain upper extremity stability test prior to throwing three fastballs at game speed to a catcher with the fastest fastball used for analysis. Spearman's Rho were used to examine relationships between energy flow in and out of the humerus with glenohumeral stability as determined by the average score and normalized stance width during the closed kinetic chain upper extremity stability test. There was a significant negative correlation between the average score and normalized peak power leaving the humerus (r _s[22]=-0.42, p=0.04). This result provides preliminary support for the use of the closed kinetic chain upper extremity stability test as a clinical assessment of a pitcher's ability to efficiently transfer energy within the upper extremity during the pitch.

Peak horizontal ground reaction forces and impulse correlate with segmental energy flow in youth baseball pitchers

The purpose of this study was to determine associations between horizontal ground reaction force (GRF) kinetics and energy flow (EF) variables in youth baseball players. Twenty-four youth baseball players pitched fastballs in an indoor laboratory while motion capture and force plate data were collected. Horizontal GRF variables were extracted (peak GRF and GRF impulse) while EF was calculated by integrating magnitudes of mechanical powers transferred into and out of the pelvis, trunk, and arm segments via joint force power (JFP) and joint moment power (JMP) components. Peak propulsive GRF of the drive (back) leg correlated with EF into proximal segments, whereas peak braking GRF of the stride (lead) leg correlated with EF into distal segments. Furthermore, peak GRF of the drive leg and GRF impulse of both legs correlated with the JFP components of EF into the pelvis and trunk segments. In contrast, peak GRF and GRF impulse of the stride leg both correlated with the JMP components of EF into the arm segment. These results suggest that horizontal GRF impulse from the drive and stride leg contribute to EF between major segments of the lower and upper extremity. In addition, these results also suggest that propulsion kinetics of the drive leg play a role in transferring linear power via the pelvis and trunk segments in the throwing direction of the pitch, whereas braking kinetics of the stride leg play a role in creating rotational power that is transferred between the trunk and arm segment via the shoulder joint.

Individual factors associated with baseball pitching performance: scoping review

BACKGROUND

Ball velocity, accuracy and game statistics represent three methods used to measure pitching performance. However, individual determinants of pitching performance are more elusive.

OBJECTIVES

The aims of this study were to classify the performance factors associated with baseball pitchers, to identify the methods used to quantify their abilities through all features of the game and to document relationships between performance factors and indicators.

DESIGN

Scoping review.

DATA SOURCES

Electronic searches of MEDLINE, Academic Search Complete, CINAHL, SportDiscus, PubMed, PsycINFO, Cochrane and of grey literature were undertaken from inception to January 2019.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Cross-sectional studies that investigated the relationship between performance indicators and individual performance factors in healthy baseball pitchers were selected.

RESULTS

Thirty-four cross-sectional studies investigating individual potential factors of pitching performance met the inclusion criteria. The primary performance factors investigated were kinematic, kinetic, timing outcomes, personal characteristics, physical tests and range of motion. Shoulder horizontal adduction (SHA), upper torso forward flexion, maximal shoulder external rotation, upper torso rotation angle, upper torso lateral flexion, lead knee flexion (LKF) and forward trunk tilt (FTT) were identified as key kinematic features associated with increased ball velocity. Shoulder proximal force and peak elbow proximal forces were associated with greater ball velocity. Individual performances in jumping tests and body weight (BW) are also associated with pitching performance.

SUMMARY/CONCLUSION

Based on studies presenting low and moderate risk of bias, we conclude that BW, age and kinematics, such as FTT, LKF, SHA and lateral trunk tilt, are associated with pitching performance.

Induced power analysis of sequential body motion and elbow valgus load during baseball pitching

The flow of mechanical energy of segmental motion during baseball pitching is poorly understood, particularly in relation to the valgus torque at the elbow which is prone to pitching-related injuries. This study employed an induced power analysis to determine the components of muscle and velocity-dependent torques that contribute to the power of throwing arm segments when the elbow is under valgus load during the arm-cocking phase of pitching. The 3D throwing kinematics and kinetics of 10 adult pitchers were included in this analysis. Pitchers threw with a maximum elbow valgus torque of 73 ± 20 N•m. The trunk flexion and rotation components of the velocity-dependent torque were the greatest contributors to the work of the forearm at -0.53 ± 0.22 J/kg and -0.43 ± 0.21 J/kg, respectively. Approximately 86% of the total energy transferred through the elbow by the velocity-dependent torque was due to trunk motion, which appears to drive the power of accelerating the throwing elbow in valgus. These results support the importance of trunk motion as a key component in the development of elbow torque and ball velocity. Therefore, this study has practical implications for baseball pitchers seeking to minimise injury risk while improving performance.

Absolute and Relative Strength, Power and Physiological Characteristics of Indian Junior National-Level Judokas

The physical qualities that underpin successful junior judokas requires continuing investigation. We investigated the physical and physiological characteristics of junior national level judokas. We tested 25 (15 male, 10 female) Indian judokas for absolute and relative strength (back-squat and bench-press one-repetition maximum (1RM) as well as isometric handgrip), aerobic (RAMP test) and lower-body anaerobic power (Wingate 6-s sprint and countermovement jump), change-of-direction (5-0-5 test) and speed (30 m sprint). Athletes were grouped according to national-level competition placing (gold-medal winners (GM; n = 8), all medal winners (MW; n = 13), non-medallists (NM; n = 12), and NM plus silver and bronze; all others (AO; n = 17)). Stepwise discriminant function analysis determined characteristics likely to predict successful performance. Independent t-tests and effect size (Hedge’s g) analyses were performed between groups. GM demonstrated greater lower-body absolute (20.0%; g = 0.87, p = 0.046) and relative 1RM strength (21.0%; g = 0.87, p = 0.047), and greater lower-body absolute (25.4%; g=1.32, p=0.004) and relative (27.3%; g = 1.27, p = 0.005) anaerobic power compared to AO. Furthermore, anaerobic power can correctly predict 76.5% and 62.5% of AO and GM athletes, respectively. No differences were observed between MW and NM groups. The results suggest the importance of lower-body strength and power for junior national-level judokas and provides information for professionals working with these athletes.

Glenohumeral external rotation weakness partially accounts for increased humeral rotation torque in youth baseball pitchers

OBJECTIVES

To examine differences in shoulder internal rotation (IR) torque among youth pitchers of above and below average relative glenohumeral (GH) rotation strength levels. It was hypothesized that differences in IR torque during the pitching motion would could be explained by differences in relative IR and external rotation (ER) strength.

DESIGN

Descriptive laboratory study.

METHODS

Isometric GH rotation strength and upper extremity pitching mechanics were assessed in 78 male youth baseball pitchers (12.7±2.0yrs; 1.63±14.0m; 56.9±12.4kg). Shoulder IR torque during the pitch was examined at maximum humeral external rotation (MER) and throughout the arm acceleration phase (ACC). Multivariate analysis of covariance (MANCOVA) was used to examine the differences in pitching IR torque between GH strength groups.

RESULTS

A significant main effect of ER strength on the dependent variables was present after controlling for fastball velocity (λ=0.855, F_2,72=6.13, p=0.003, η_p²=0.145). Follow up univariate tests indicated significant differences in IR torque between strength groups at MER (F_1,73=12.36, p<0.001, η_p²=0.145) and during ACC (F_1,73=6.65, p= 0.012, η_p²=0.083). Participants who displayed ER strength at or below the group mean experienced greater IR torque at MER and greater average IR torque during ACC than participants who displayed ER strength above the group mean.

CONCLUSIONS

Weakness of the GH ER musculature partially accounts for increased shoulder IR torque during pitching.