Kinematic Modeling of Pitch Velocity in High School and Professional Baseball Pitchers: Comparisons With the Literature.

Background: Kinematic parameters predictive of pitch velocity have been evaluated in adolescent and collegiate baseball pitchers; however, they have not been established for high school or professional pitchers. Purpose: To create multiregression models using anthropometric and kinematics features most predictive for pitch velocity in high school and professional pitchers and compare them with prior multiregression models evaluating other playing levels. Study Design: Descriptive laboratory study. Methods: High school (n = 59) and professional (n = 337) baseball pitchers threw 8 to 12 fastballs while being evaluated with 3-dimensional motion capture (480 Hz). Using anthropometric and kinematic variables, multiregression models for pitch velocity were created for each group. A systematic review was conducted to determine previous studies that established kinematic models for ball velocity in youth, high school, and collegiate pitchers. Results: Leg length was predictive of pitch velocity for high school and professional pitchers (P < .001 for both). When compared with previously established models for pitch velocity, almost all groups were distinct from one another when assessing age (P maximum < .001), weight (P max = .0095), and pitch velocity (P max < .001). Stride length was a significant predictor for the youth/high school pitchers, as well as the current study's high school and professional pitchers (P < .001 for all). Maximal shoulder external rotation (collegiate: P = .001; professional: P < .001) and maximal elbow extension velocity (high school/collegiate: P = .024; collegiate: P < .001; professional: P = .006) were shared predictors for the collegiate and current study's professional group multiregression models. Trunk flexion at ball release was a commonly shared predictor in the youth/high school (P = .04), high school/collegiate (P = .003), collegiate (P < .001), and the current study's professional group (P < .001). Conclusion: Youth, high school, collegiate, and professional pitchers had unique, predictive kinematic and anthropometric features predictive of pitch velocity. Leg length, stride length, trunk flexion at ball release, and maximal shoulder external rotation were predictive features that were shared between playing levels. Clinical Relevance: Coaches, clinicians, scouts, and pitchers can consider both the unique and the shared predictive features at each playing level when attempting to maximize pitch velocity.

Is isokinetic shoulder strength a determinant of serve ball velocity in tennis?

The tennis serve is closely related to the quality of the tennis match. However, the isokinetic parameters associated with the tennis serve are still unclear. The aim of this study was to investigate the relationships between ball velocity and isokinetic shoulder strength in tennis serve and to determine isokinetic strength parameters that can predict tennis serve velocity. A total of 13 elite male athletes (16.8 ± 1.5 years) voluntarily participated in the study. The athletes' shoulder internal-external rotation, extension-flexion and abduction-adduction strengths were measured with 5-5-15 repetitions at 60°/s, 180°/s, 240°/s angular velocities. Later, the athletes' 1st, 2nd, and average serve ball speeds were determined using a handheld radar gun. Significant correlations were found between ball speed and isokinetic tennis serve strength (r = 0.556-0.819; p < 0.05). The correlations between ball speed and isokinetic strength performance were higher at 180°/s and 240°/s angular velocities. Extension (240°/s; r = 0.819), flexion (180°/s; r = 0.755), abduction (240°/s; r = 0.733), adduction (240°/s; r = 0.684) and internal rotation (180°/s; r = 0.803) were highly correlated with ball velocity. These findings suggest that strength training to increase the ball speed of the tennis serve should be performed fast at high angular velocities and planning should focus on the strength of extension, flexion, abduction, adduction and internal rotation.

Effects of ice slurry ingestion on body temperature and softball pitching performance in a hot environment: a randomized crossover trial.

BACKGROUND: Although softball players are often required to play in hot environments, scarce evidence is available regarding the effects of ice slurry ingestion on body temperature and pitching performance in softball pitchers in a hot environment. Thus, this study investigated the effects of ice slurry ingestion before and between innings on body temperature and softball pitching performance in a hot environment. METHODS: In a randomized crossover design, seven heat-acclimatized amateur softball pitchers (four males and three females) completed simulated softball games consisting of 15 best-effort pitches per inning for seven innings with between-pitch rest intervals of 20 s. Participants were assigned to either a control trial (CON: ingestion of 5.0 g·kg-1 of cool fluid [9.8 ± 2.2 °C] before simulated softball games and 1.25 g·kg-1 of cool fluid between inning intervals) or an ice trial (ICE: ingestion of ice slurry [- 1.2 ± 0.1 °C] based on the same timings and doses as the CON). Participants performed both trials in an outdoor ground during the summer season (30.8 ± 2.7 °C, 57.0 ± 7.9% relative humidity). RESULTS: Ice slurry ingestion before the simulated softball game (pre-cooling) resulted in a greater reduction in rectal temperature compared with cool fluid ingestion (p = 0.021, d = 0.68). No significant differences were observed between the trials in rectal temperature changes during the simulated softball game (p > 0.05). Compared to the CON, heart rate during the game was significantly decreased (p < 0.001, d = 0.43), and handgrip strength during the game was significantly increased (p = 0.001, d = 1.16) in the ICE. Ratings of perceived exertion, thermal comfort, and thermal sensation were improved in the ICE compared to those in the CON (p < 0.05). Ball velocity and pitching accuracy were not affected by ICE. CONCLUSIONS: Ice slurry ingestion before and between innings reduced thermal, cardiovascular, and perceptual strain. However, it did not affect softball pitching performance compared to cool fluid ingestion.

Conditioning Strategies for Improving Handball Throwing Velocity: A Systematic Review and Meta-Analyses.

Ball throwing velocity is essential for scoring goals in handball; the crucial question is how to develop throwing velocity in highly trained handball players. Therefore, this systematic review aims to summarize effective conditioning strategies to improve throwing velocity in elite male players and to perform a meta-analysis on which training system can provide the highest increase in throwing velocity. The literature was analyzed using the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) in PubMed, Scopus, and Web of Science. Thirteen studies (sample n = 174) were included: five resistance training studies, one core training study, one study on repeated shuffle sprint training with small-sided games, and one on eccentric overload training. Effect size comparison showed that resistance training is the most effective strategy for improving throwing velocity in elite handball players (d > 0.7). Core training showed a small effect (d = 0.35). Small-sided game (SSG) training showed different results, from a significant positive effect (d = 1.95) to a negative effect (d = -2.03), and eccentric overload training showed a negative effect (d = -0.15). Resistance training is the most effective strategy for improving throwing velocity in elite handball players, while core training and SSGs can improve throwing velocity in youth athletes. Due to the small number of studies focusing on elite handball players, there is a need for more studies on advanced resistance training methods, e.g., contrast, complex, ballistic training, because much greater demands are placed on handball performance assumptions.

Forearm Pronation at Foot Contact: A Biomechanical Motion-Capture Analysis in High School and Professional Pitchers.

Background: It has previously been speculated that baseball pitchers who display excessive forearm pronation at foot contact (FC) have a higher propensity toward ulnar collateral ligament injury and subsequent surgery. Purpose: To evaluate the association between degree of forearm pronation/supination at FC and throwing arm kinetics in high school and professional pitchers, at both the individual (intrapitcher) and the group (interpitcher) level. Study Design: Descriptive laboratory study. Methods: High school (n = 41) and professional (n = 196) pitchers threw 8 to 12 fastballs while being assessed with a 3-dimensional motion-capture system (480 Hz). Pitchers at each playing level were divided into a supination or pronation subgroup depending on degree of forearm pronation at FC. Regression models were built to observe the relationship between forearm pronation at FC and kinetic and kinematic parameters of interest. Results: At both the individual and the group level of high school and professional pitchers, there was no significant correlation between forearm pronation at FC and elbow varus torque (P min = .21). For every 10° increase in forearm pronation at FC in the individual high school pitcher, elbow flexion at FC decreased by 5°, whereas maximum elbow extension velocity was achieved 0.6% later in the pitch. In addition, elbow medial force increased by 4.1 N and elbow varus torque increased by 0.8 N·m for every 10° increase in forearm supination at FC. For every 10° increase in forearm supination in the individual professional pitcher, ball velocity increased by 0.5 m/s, shoulder external rotation at FC decreased by 11°, and elbow medial force decreased by 5.5 N. Conclusion: Supination- or pronation-predominant forearm motion during the pitch did not significantly differ between playing levels. Excessive forearm pronation at FC was not a significant risk factor for increased throwing arm kinetics for high school or professional pitchers. There was a weak positive association between forearm supination at FC and elbow varus torque in the individual high school pitcher. Ultimately, coaches and pitchers may be better served by redirecting their focus to other mechanical aspects of the pitch that may have stronger associations with injury risk implications as well as performance.

Do the Pelvic and Thorax Movements Differ between the Sexes and Influence Golf Club Velocity in Junior Golfers?

The aim of this study was to determine the differences in golf swing execution in terms of the parameters of the pelvis and thorax movement between the sexes in junior golfers and their relation to the golf club velocity. Elite female and male players (age: 15.4 ± 1.0 and 15.8 ± 1.7 years, respectively) performed 10 golf swings with a driver under laboratory conditions. Pelvis and thorax movement parameters and golf club velocities were measured using a three-dimensional motion capture system. Statistical parametric mapping analysis of pelvis-thorax coupling revealed a significant difference (p < 0.05) between boys and girls during backswing. Analysis of variance showed a significant effect of sex on the parameters of maximal pelvic rotation (F = 6.28, p = 0.02), X-factor (F = 5.41, p = 0.03), and golf club velocity (F = 31.98, p < 0.01). No significant relationship was found between pelvis and thorax movement parameters and golf club velocity in the girls. We found a significant negative relationship between the parameters of maximal thorax rotation and golf club velocity (r = -0.941, p < 0.01) and between X-Factor and golf club velocity (r = -0.847, p < 0.05) in the boys. We suggest that these negative relationships in males were caused by the influence of hormones during their maturation and biological development, where there is decreased flexibility (lower shoulders rotation and X-factor) and growth of muscle strength (higher club head velocity).

Effect of difficulty of task on throwing performance and coping strategies in team handball.

In this study the effect of level of opposition on throwing performance and coping strategies in the jump throw was examined in elite, amateur, and adolescent players in team handball. Twenty four participants consisting of 13 female elite junior handball players (age: 15.5 ± 0.7 years; height: 1.72 ± 0.07 m; body mass: 64.2 ± 7.0 kg; years of handball experience: 8.4 ± 1.76 years) and 11 senior recreational female handball players (age: 19.5 ± 1.04 years; height: 1.68 ± 0.08 m; body mass: 65.2 ± 9.3 kg; years of handball experience: 11 ± 2.61 years) performed ten jump throws under four conditions: (1) without opposition; (2) with a passive opponent; (3) with an opponent moving sideways; and (4) with a defender who was instructed to be unpredictable without physical contact with the thrower. Ball velocity and accuracy were measured for every throw together with answering a questionnaire consisting of 18 questions after each condition to investigate if coping strategies changed with increasing difficulty of task and if this was different for playing level. The main findings were that ball velocity and accuracy decreased when opposition was introduced, but with no differences when the opposition moved only sideways or unpredictably (forwards and/or sideways), similarly for both groups. Furthermore, the level had no influence on the coping strategies or a relationship with either of these coping strategies, but the avoidance coping strategy scored lower than the other two categories for both groups. It was concluded that level of opposition had a negative effect on throwing velocity and accuracy in elite junior and recreational level senior players which was probably caused by the change of given attention to one target (overcome opponent), which leaves less available for others (throwing velocity and accuracy). Furthermore, coping strategies did not change or have any correlation with throwing performance, indicating that these strategies seem to be influenced by trait and that most players mainly used problem- and emotional-focused coping strategies and less avoidance strategies when dealing with the level of opposition.

Effect of quantitative partial valgus stress during baseball pitching on ball velocity and subjective pitch-effort.

BACKGROUND: Excessive elbow valgus stress can often cause pitching elbow injuries, and rehabilitation is usually required before an athlete can resume playing. However, there is a lack of information on the partial load rehabilitation of pitching elbow injuries caused by valgus extension overload based on elbow valgus stress. The purpose of this study was to clarify how quantitative partial elbow valgus stress while pitching affects ball velocity and subjective pitch-effort. METHODS: Forty-six male baseball pitchers participated in this study. Each player wore a wearable device on the elbow that collected their pitch parameters. Ball velocity was measured using a radar gun. Each elbow valgus stress was measured while each player was instructed to throw 5 fastballs at full effort. Then, based on the average stress of the 5 throws (100% partial valgus stress), the 75% and 50% stresses were calculated (75% and 50% partial valgus stress, respectively). Each pitcher continued to pitch until the number of pitches thrown at the targeted elbow stress reached 5. Each player was asked about their subjective pitch-effort after completing each type of partial valgus stress pitch. Outcomes were statistically evaluated using either a 1-way repeated measures analysis of variance or 2-way analysis of variance. RESULTS: The ball velocity was 72% (95% confidence interval [CI], 69%-75%) and 58% (95% CI, 55%-61%) during the 75% and 50% partial valgus stress, respectively (P < .001). Subjective pitch-effort was 41% (95% CI, 38%-44%) and 19% (95% CI, 16%-22%) while pitching at 75% and 50% partial valgus stress, respectively (P < .001). CONCLUSIONS: It may be desirable to instruct pitchers to throw at less than 20% subjective pitch-effort of the max if they want to pitch at 50% partial valgus stress. Elbow valgus stress might correlate with ball velocity at 75% partial valgus stress pitch. These results could enable clinicians and coaches to perform safer return-to-throwing programs and prevent excessive load on the elbow.

Attack and Defense Performance in Goalball: A Proposal for Throwing, Balance and Acoustic Reaction Evaluation.

Goalball is a sport for visually impaired athletes, where the roles of attack and defense change continuously during the game. Performance evaluation should consider the variables that determine the throwing and the stop and clearance of the ball. The aim of this study is to evaluate the precision and velocity of the ball throwing in goalball, besides core stability and balance as variables that determine an optimal throwing. Moreover, a novel acoustic reaction time is applied to analyze the defense performance. Eight goalball players (33 ± 9 years old; 77.8 ± 22.7 kg; 174 ± 13 cm; 10 ± 5 years of experience) were recruited to assess ball velocity, with a radar gun, and throwing accuracy. Anthropometry, static balance, and core stability were assessed using a computerized pressure platform. Acoustic reaction time was measured with a photoelectric system. A significant positive correlation was found between throwing speed and the years of experience (Ç· = 0.714, p = 0.047), height (Ç· = 0.786, p = 0.021), dominant leg surface area of the stabilogram (Ç· = 0.738, p = 0.037), and non-dominant leg center of pressure mean velocity (Ç· = 0.714, p = 0.017). In the present pilot study, height and years of experience are correlated to throwing velocity. This is also the first test proposal to assess throwing precision and complex acoustic reaction in goalball players, which could be used to assess the level of performance in future studies.

The influence of shoulder abduction and external rotation on throwing arm kinetics in professional baseball pitchers.

Background: The relationships between shoulder abduction and external rotation with peak kinetic values at the shoulder and elbow in professional baseball pitchers are not well established. Methods: Professional pitchers (n = 322) threw 8-12 fastballs under 3D motion analysis (480 Hz). Pitchers were stratified into quartiles by shoulder abduction and external rotation at distinct timepoints. Regression analyses were performed to quantify associations between shoulder position and kinetics. Results: Shoulder abduction remained relatively consistent throughout the pitch (foot contact-ball release: 85.5 ± 11.1-90.7 ± 8.4°); shoulder external rotation increased dramatically (foot contact-ball release: 30.8 ± 24.6-165.2 ± 9.7°). For every 10° increase in maximum shoulder rotation, shoulder superior force increased by 2.3% body weight (p < 0.01), shoulder distraction force increased by 5.9% body weight (p < 0.01), and ball velocity increased by 0.60 m/s (p < 0.01). Shoulder abduction was significantly associated with shoulder superior force at all timepoints but not with ball velocity (p > 0.05). For every 10° increase in shoulder abduction at ball release, shoulder superior force increased by 3.7% body weight (p < 0.01) and shoulder distraction force increased by 11.7% body weight (p < 0.01). Conclusion: Increased shoulder abduction at ball release and increased maximum shoulder external rotation were associated with greater superior and distraction forces in the shoulder. Pitchers can consider decreasing shoulder abduction at later stages of the pitch to around 80° in order to minimize shoulder superior force, with no impact on ball velocity.

Specific Game-Based Performance in Elite Male Adolescent Team Handball Players.

PURPOSE: In elite team handball, talent identification and selection of the best young players is a fundamental process in several national federations and clubs; however, literature addressing the specific game-based performance in team handball is almost nonexistent. Consequently, the aim of the study was to assess and compare the team-handball-specific game-based performance of elite male team handball players of different ages. METHODS: Twelve under-23, 10 under-19, 10 under-17, and 10 under-15 elite male players performed the team-handball game-based performance test. During testing, oxygen uptake, heart rate, sprinting time in defense, offense, fast breaks, and fast retreats, as well as ball velocity and jump height in the jump shot, were measured. RESULTS: Significant differences (P < .05) between under-23, under-19, under-17, and under-15 players were found for absolute peak oxygen uptake, defense, offense and fast break time, ball velocity, and jump height in the game-based performance test, as well as in body weight and height. CONCLUSION: The results revealed that with increasing age, elite male team handball players are heavier and taller (body weight and height); faster (team-handball offense, defense, and fast break); jump higher and throw faster (in the team-handball jump shot); and perform better aerobically (absolute peak oxygen uptake). The better performance in the under-23 and under-19 players compared with male adult players competing in a lower National Federation league (not on top-elite level) demonstrates that highly specific game-based physical performance determines the potential for developing young male team handball players for competition at the top level.

Normalized Isometric Shoulder Strength as a Predictor of Ball Velocity in Youth Baseball Players.

BACKGROUND: Despite increased awareness of factors related to athletic performance and injury prevention, youth and adolescent baseball players continue to report injuries at alarming rates. Upper extremity muscle strength is an integral part of physical assessment and injury prevention in baseball players, however minimal data exists in youth populations. Changes in anthropometric measures, inherent in physically developing athletes, have been shown to impact strength measures, however normalization methodology is rarely reported. PURPOSE: The purposes of this study were to 1) compare the measurement properties of five potential methods for normalizing isometric shoulder strength in a cohort of 9-12 year old male baseball players and 2) examine the relationship between normalized isometric shoulder strength and ball velocity in a cohort of 9-12 year old male baseball players. STUDY DESIGN: Prospective cohort study (n=159). METHODS: Baseline and follow up height, weight and bilateral ulnar length measurements were assessed followed by isometric strength in both the dominant and non-dominant shoulders. Strength measures included scapular plane abduction (scaption), external rotation (ER) at 0°, ER and internal rotation (IR) at 90°. Ball velocity was assessed as a measure of throwing performance. Intraclass correlation coefficients (ICC2,1), standard errors of measurement (SEM) and minimal detectable change (MDC95) were calculated for all strength measures. Repeated measures ANOVA were conducted comparing changes in normalized strength using five separate anthropometric measures: weight, height, body mass index, ulnar length and % of non-dominant shoulder strength. Linear regression models were used to examine the relationships between normalized isometric shoulder strength and ball velocity. Statistical significance was set a priori at α=0.05. RESULTS: Shoulder strength normalized using ulnar length was the only method that demonstrated excellent reliability (ICC2,1 0.98-0.99) and detected significant changes between strength in each of the four measures tested (SEM 0.39-0.69 Nm). Modest but significant correlations were observed between scaption and ball velocity (r2 = 0.27, p < 0.001) and ER at 0° and ball velocity (r2 = 0.23, p < 0.001). CONCLUSION: Ulnar length was the most stable and reliable normalization method for assessing isometric shoulder strength in youth baseball players. In addition, normalized scaption strength was the most significant predictor of ball velocity, followed by ER at 0° strength in this population. LEVEL OF EVIDENCE: Level 2b (etiology).

Individualised Ball Speed Prediction in Baseball Pitching Based on IMU Data.

Ball velocity is considered an important performance measure in baseball pitching. Proper pitching mechanics play an important role in both maximising ball velocity and injury-free participation of baseball pitchers. However, an individual pitcher's characteristics display individuality and may contribute to velocity imparted to the ball. The aim of this study is to predict ball velocity in baseball pitching, such that prediction is tailored to the individual pitcher, and to investigate the added value of the individuality to predictive performance. Twenty-five youth baseball pitchers, members of a national youth baseball team and six baseball academies in The Netherlands, performed ten baseball pitches with maximal effort. The angular velocity of pelvis and trunk were measured with IMU sensors placed on pelvis and sternum, while the ball velocity was measured with a radar gun. We develop three Bayesian regression models with different predictors which were subsequently evaluated based on predictive performance. We found that pitcher's height adds value to ball velocity prediction based on body segment rotation. The developed method provides a feasible and affordable method for ball velocity prediction in baseball pitching.

The Effects of Target Location Upon Throwing Velocity and Accuracy in Experienced Female Handball Players.

The purpose of this study was to investigate the effect on throwing performance (velocity and accuracy) of experienced female handball players when throwing at four different targets in a handball goal. Thirteen experienced female handball players (age 18.2 ± 1.7 years, height 1.7 ± 0.10 m, mass 68.1 ± 19.6 kg, and training experience 9.5 ± 3.7 years) performed 10 throws from a 7 m distance at each corner of the handball goal with maximal effort. Maximal ball velocity was recorded with a radar gun together with mean radial error, centroid error, and bivariate variable error, as measurements of accuracy. The main findings were that the ball velocity was higher when throwing at targets at the ipsilateral side, compared with the contralateral side, while throwing consistency (bivariate variable error) decreased when throwing at the contralateral side upper corner. No velocity-accuracy trade-off was found between the four targets. Based upon the findings, it is suggested that players throw to the (upper) ipsilateral side of the goal when performing a penalty throw, dependent on the goalkeepers' position, since the ball velocity is the highest here, without losing accuracy. This gives the goalkeeper less time to react and stop the ball, thereby giving the player the highest chance of scoring.

The effect of fatigue and duration knowledge of exercise on kicking performance in soccer players.

PURPOSE: The purpose of this study was to investigate the influence of fatigue upon kicking maximal ball velocity and the target-hitting accuracy of soccer players; and also to examine the effect of the knowledge of the exercise duration upon these 2 parameters. METHODS: Twenty-four semi-professional soccer players participated in this study and performed maximal instep kicks before and after the implementation of an exercise protocol, either with or without knowledge of the duration of this protocol. RESULTS: A mixed model of analysis of variance showed that kicking maximal ball velocity was significantly affected (F(5, 85) = 11.6, p < 0.001, η 2 = 0.39) but only after just 1 circuit of the fatigue protocol and then remained similar. Accuracy did not change during the protocol (F(5, 75) = 0.23, p = 0.76, η 2 = 0.03) and knowing the duration of exercitation did not affect accuracy and velocity development (F(1, 23) ≤ 1.04, p ≥ 0.32, η 2 ≤ 0.06). CONCLUSION: These findings demonstrated the potential negative effects of fatigue on kicking ball velocity in soccer but not in the kicking accuracy and that the effect of fatigue may not be progressive over time. Knowing or not knowing the duration of exercitation did not affect the results.

Variability in Baseball Throwing Metrics During a Structured Long-Toss Program: Does One Size Fit All or Should Programs Be Individualized?

BACKGROUND: The variability of throwing metrics, particularly elbow torque and ball velocity, during structured long-toss programs is unknown. HYPOTHESES: (1) Elbow torque and ball velocity would increase as throwers progressed through a structured long-toss program and (2) intrathrower reliability would be high while interthrower reliability would be variable. STUDY DESIGN: Descriptive laboratory study. LEVEL OF EVIDENCE: Level 3. METHODS: Sixty healthy high school and collegiate pitchers participated in a structured long-toss program while wearing a validated inertial measurement unit, which measured arm slot, arm velocity, shoulder rotation, and elbow varus torque. Ball velocity was assessed by radar gun. These metrics were compared within and between all pitchers at 90, 120, 150, and 180 ft and maximum effort mound pitching. Intra- and interthrower reliabilities were calculated for each metric at every stage of the program. RESULTS: Ball velocity significantly changed at each progressive throwing distance, but elbow torque did not. Pitching from the mound did not place more torque on the elbow than long-toss throwing from 120 ft and beyond. Intrathrower reliability was excellent (intraclass correlation coefficient >0.75) throughout the progressive long-toss program, especially on the mound. Ninety-one percent of throwers had acceptable interthrower reliability (coefficient of variation <5%) for ball velocity, whereas only 79% of throwers had acceptable interthrower reliability for elbow torque. CONCLUSION: Based on trends in elbow torque, it may be practical to incorporate pitching from the mound earlier in the program (once a player is comfortable throwing from 120 ft). Ball velocity and elbow torque do not necessarily correlate with one another, so a degree of caution should be exercised when using radar guns to estimate elbow torque. Given the variability in elbow torque between throwers, some athletes would likely benefit from an individualized throwing program. CLINICAL RELEVANCE: Increased ball velocity does not necessarily equate to increased elbow torque in long-toss. Some individuals would likely benefit from individualized long-toss programs for rehabilitation.

Baseball Pitchers' Perceived Effort Does Not Match Actual Measured Effort During a Structured Long-Toss Throwing Program.

BACKGROUND: During rehabilitation throwing programs, baseball players are commonly asked to throw at reduced levels of effort (ie, 50% effort, 75% effort, etc) to moderate stress to healing tissues. It is currently unknown how changes in players' perceived exertion compares with changes in actual exertion during structured long-toss programs. PURPOSE: To determine whether decreased effort correlates with decreased throwing metrics, whether metrics decrease proportionally with reductions in perceived effort, and to quantify intrathrower variability. STUDY DESIGN: Descriptive laboratory study. METHODS: Sixty male high school and collegiate baseball pitchers participated in a structured throwing program. A motusBASEBALL sleeve was worn by all players, which measured elbow varus torque, arm velocity, arm slot, and shoulder rotation. Ball velocity was measured with a radar gun. Each pitcher threw 5 throws a distance of 120 ft with 3 efforts: maximum effort, 75% effort, and 50% effort. Throwing metrics were compared among the 3 levels of effort to see if each 25% decrease resulted in proportional decreases in elbow varus torque and ball velocity. Intrathrower variability was determined for each throwing metric at each degree of effort. RESULTS: All throwing metrics decreased as players decreased their perceived effort (P < .001). However, these observed decreases were much smaller in magnitude than the decreases in perceived effort. During the 75% effort throws, elbow varus torque was only reduced to 93% of maximum and velocity dropped to 86% of maximum. Similarly, for the 50% effort throws, elbow varus torque remained 87% of max effort torque, while velocity remained 78% of max. Intrathrower reliability was considered excellent for most metrics (intraclass correlation coefficient, >0.75). CONCLUSION: For every 25% decrease in perceived effort, elbow varus torque only decreased 7% and velocity only decreased 11%. Thus, when players throw at what they perceive to be reduced effort, their actual throwing metrics do not decrease at the same rate as their perceived exertion. CLINICAL RELEVANCE: Measured effort decreased with decreasing perceived effort, but these were not proportional. This has significant implications for physical therapists, physicians, trainers, coaches, and athletes to understand and monitor elbow stress during the rehabilitation process.

Functional Mobility and Dynamic Postural Control Predict Overhead Handball Throwing Performance in Elite Female Team Handball Players.

The relationship between dynamic postural control, functional mobility and team handball throwing performance, velocity and accuracy, is largely unknown. The hand reach star excursion balance test (HSEBT) is a full kinetic chain assessment tool of these factors. Specifically, L135 and R135 (extension) reaches elicit joint movement combinations similar to the cocking and acceleration phase, while the L45 and R45 (flexion) reaches elicit joint movement combinations similar to the follow-through. The purpose of this study was to determine if specific HSEBT reach measures correlate with team handball throwing performance. Eleven elite female team handball players (21.7 ± 1.8 years; 71.3 ± 9.6 kg; 1.75 ± 0.07 m) executed selected HSEBT reaches before performing five valid step-up overhead throws (1x1m target) from which throwing velocity (motion capture) and accuracy (mean radial error) were quantified. Significant relationships between HSEBT measures and mean radial error, but not throwing velocity were established. Specifically, extension composite scores (L135+R135) for the dominant (150.7 ± 17.4cm) and non-dominant foot (148.1 ± 17.5 cm) were correlated with mean radial error (p < 0.05). Also, specific reaches on the dominant (L135: 87.4 ± 5.6 cm; R135: 63.4 ± 11.8 cm) and non-dominant (R135: 87.0 ± 6.1 cm) foot were correlated with throwing error (p < 0.05). The lack of significant findings to throwing velocity might be due to a ceiling effect of both L135 and R135 and of throwing velocity. We conclude that while there may be other reasons for handball players to train and test functional mobility and dynamic postural control as measured in the HSEBT, no beneficial effect on throwing performance should be expected in an elite group of handball players.

Movement characteristics of volleyball spike jump performance in females.

OBJECTIVES: Performance factors in the volleyball spike jump are well known for male players; however, technical-coordinative differences for female players are known only marginally. The objective of this study was to investigate the relationship between movement characteristics and female' spike jump performance and to identify the most relevant aspects of jump height and ball velocity. DESIGN: Single group correlation and regression. METHODS: Fifteen elite female volleyball players performed spike jumps by striking a stationary ball at maximal jump height. Data were collected via twelve MX13 Vicon cameras (250Hz), two AMTI force plates (2000Hz), and controlled via Visual3D software. RESULTS: Ten out of 42 characteristics correlated with jump height and none of 22 correlated with ball velocity. A stepwise regression model (adjusted R2=0.82, p<0.001) predicted jump height based on orientation step length and maximal angular velocity of dominant knee extension. For ball velocity, stepwise regression analysis was not feasible; however, an alternative model yielded adjusted R2=0.55, p<0.01. CONCLUSIONS: Key aspects for jump height were (1) optimised approach and energy conversion, (2) wide dynamic arm swing allowing for a forceful countermovement and, thus, increased range of motion in lower limbs, and (3) large angular velocities in ankles and knees, especially on the dominant side. These aspects strongly determined jump height in females and should be included in technical and strength-related training. For ball velocity, upper body anthropometrics and angular joint velocities emerged as the most important criteria. The importance of specific joints may depend on variations in striking technique.

Acute effects of different warm-up protocols on highly skilled golfers' drive performance.

Previous research has highlighted the positive effect that different warm-up protocols have on golf performance (e.g. Sorbie et al., 2016; Tilley & Macfarlane, 2012) with the design of warm-ups and programmes targeting and improving golf performance through the activation and development of specific muscle groups. This study aimed to examine the acute effects of two warm-up protocols on golf drive performance in comparison to a control condition. Using a randomised counterbalanced design over three testing sessions, twenty-three highly skilled golfers completed the control, dynamic and resistance-band warm-up conditions. Following each condition, a GC2 launch monitor was used to record ball velocity and other launch parameters of ten shots hit with the participants' own driver. A repeated-measures ANOVA found significant increases in ball velocity (ηp2 = .217) between the control and both the dynamic and resistance-band warm-up conditions but no difference between these latter two, and a reduction in launch angle between control and dynamic conditions. The use of either a dynamic stretching or resistance-band warm-up can have acute benefits on ball velocity but golfers should liaise with a PGA Professional golf coach to effectively integrate this into their golf driving performance.