Changes in Throwing Arm Mechanics at Increased Throwing Distances During Structured Long-Toss

Elbow valgus stress during towel drills in college baseball players

BACKGROUND

In baseball players with elbow injuries, towel drills are clinically used before initiating active throwing exercises to gradually increase stress across the elbow. However, elbow valgus torque during towel drills remains unknown. Moreover, towel drills and active ball throws might have different relationships between biomechanical metrics, such as elbow stress, arm slot, and arm speed. Therefore, the aims of this study were 1) to demonstrate the difference in elbow valgus stress between towel drills and active ball throws and 2) to evaluate the correlation between elbow valgus torque and other biomechanical metrics including arm slot and arm speed in towel drills and active ball throws.

METHODS

Seventeen healthy college baseball players performed three towel drills using a face towel, short foam tube, and long foam tube, followed by full-effort throwing on flat ground. Each participant completed five consecutive trials of each task, and the elbow valgus torque, arm slot, and arm speed were measured using wearable sensors. One-way repeated analysis of variance and post-hoc tests were used to determine the differences in biomechanical metrics among the tasks. Furthermore, the correlation between the elbow valgus torque and other metrics was evaluated using Pearson correlation coefficients.

RESULTS

Elbow valgus torque was lower in towel drills compared to that of active ball throws; however, the stress during towel drills using a face towel reached almost 80% of the maximum effort of active ball throws. There was no relationship between elbow valgus stress and arm slot in either the towel or active ball throw tasks. However, a higher arm speed was associated with greater elbow valgus torque in towel drills, whereas no relationship between elbow stress and arm speed was found in active ball throws.

CONCLUSION

Precaution must be taken in athletes following a progressive throwing program because elbow valgus stress reaches almost 80% of the full-effort throw, even when using a face towel in a towel drill. Hence, the subjective intensity must be controlled even in towel drills to gradually increase the medial elbow stress. Moreover, the mechanisms underlying changes in elbow stress may differ between towel drills and active ball throws. Future investigations on the difference between towel drills and active ball throws may help understand the underlying mechanism of alterations in elbow valgus torque during the throwing movement.

An Interval Throwing Program for Baseball Pitchers Based upon Workload Data

Background

Interval throwing programs (ITP) have been used for decades to enable baseball pitchers to return to competition after injury or surgery by gradually applying load to the throwing arm. Past programs have been based on personal experience; however, advances in our understanding of the biomechanics and workloads of throwing allow for a more modern data-based program to be developed.

Hypothesis/Purpose

To 1) develop a updated ITP for rehabilitation of modern baseball pitchers based upon biomechanical and throwing workload data, and 2) compare the updated program with a past program to determine differences in chronic workload and acute:chronic workload ratios (ACWR).

Study Design

Cross-sectional study.

Methods

Workloads (i.e. daily, acute, chronic, and ACWR) for the original ITP were built from the prescribed throwing schedule. Elbow varus torque per throw was calculated based upon a relationship between elbow varus torque and throwing distance. Throw counts, daily/chronic/acute workloads, and ACWR were calculated and plotted over time. A new ITP was built to model current pitcher's throwing schedules and gradually increased ACWR over time.

Results

The original ITP had a throwing schedule of 136 days, final chronic workload 15.0, and the ACWR above or below the "safe" range (i.e. 0.7 - 1.3) for 18% of the program with a peak of 1.61. The updated ITP was built to consist of a 217-day schedule, final chronic workload of 10.8, and deviated from the safe range for 9% of the program, with a peak of 1.33.

Conclusion

The newly created ITP is more familiar to modern baseball pitchers while exhibiting a more gradual buildup of chronic workload than traditional ITP programs. This ITP may be used to return baseball pitchers back to competition as safely and efficiently as possible, and potentially with less risk of setbacks or reinjury. The ITP may be used following common injuries or surgeries to the throwing shoulder and elbow, such as Tommy John surgery, while also serving as a basis for future development of shorter duration ITPs.

Level of Evidence

2c.

The Fundamentals and Applications of Wearable Sensor Devices in Sports Medicine: A Scoping Review

PURPOSE

To (1) characterize the various forms of wearable sensor devices (WSDs) and (2) review the peer-reviewed literature of applied wearable technology within sports medicine.

METHODS

A systematic search of PubMed and EMBASE databases, from inception through 2023, was conducted to identify eligible studies using WSDs within sports medicine. Data extraction was performed of study demographics and sensor specifications. Included studies were categorized by application: athletic training, rehabilitation, and research.

RESULTS

In total, 43 studies met criteria for inclusion in this review. Forms of WSDs include pedometers, accelerometers, encoders (consisting of magnetometers and gyroscopes), force sensors, global positioning system trackers, and inertial measurement units. Outcome metrics include step counts; gait, limb motion, and angular positioning; foot and skin pressure; change of direction and inclination, including analysis of both body parts and athletes on a field; displacement and velocity of body segments and joints; heart rate; plethysmography; sport-specific kinematics; range of motion, symmetry, and alignment; head impact; sleep; throwing biomechanics; and kinetic and spatiotemporal running metrics. WSDs are used in athletic training to assess sport-specific biomechanics and workload with a goal of injury prevention and training optimization, as well as for rehabilitation monitoring and research such as for risk predicting and aiding diagnosis.

CONCLUSIONS

WSDs enable real-time monitoring of human performance across a variety of implementations and settings, allowing collection of metrics otherwise not achievable. WSDs are powerful tools with multiple applications within athletic training, patient rehabilitation, and orthopaedic and sports medicine research.

CLINICAL RELEVANCE

Wearable technology may represent the missing link to quantitatively addressing return to play and previous performance. WSDs are commercially available and portable adjuncts that allow clinicians, trainers, and individual athletes to monitor biomechanical parameters, workload, and recovery status to better contextualize personalized training, injury risk, and rehabilitation.

Rehabilitation of the painful shoulder

Managing the painful shoulder in overhead athletes can be difficult because of a lack of time-loss injuries in overhead sports and focusing primarily on either pathoanatomic causes or movement impairments. Although managing the painful shoulder can be challenging, the combination of identifying pathoanatomic causes with movement impairments can provide a more focused rehabilitation approach directed at the causes of shoulder pain. Understanding the potential influence of scapular positioning as well as mobility and/or strength impairments on shoulder pain can help clinicians develop more directed rehabilitation programs. Furthermore, sports-specific methods such as long toss or the use of weighted balls for achieving physiological or performance-based gains have limited empirical evidence regarding their clinical and performance-based benefits, which may impede the rehabilitation process. Applying a comprehensive evaluation approach prior to and throughout the treatment process can assist clinicians with selecting the most appropriate treatment based on patient need. Reconsidering traditional treatments based on existing evidence may help refine the treatment process for overhead athletes with shoulder pain.

Biomechanical Basis of Interval Throwing Programs for Baseball Pitchers: A Systematic Review

Background

Interval throwing programs are used in rehabilitation of throwing injuries, especially ulnar collateral ligament injuries. Athletes who are rehabilitating begin by throwing on flat ground progressing through increasing distances, number of throws, and intensity of throwing. If the athlete is a baseball pitcher, the flat-ground throwing phase is followed by pitching on a mound at progressively increased effort. The goal is to build back arm strength and capacity with an emphasis on proper mechanics.

Purpose

To determine whether interval throwing progressively builds joint kinetics (specifically, elbow varus torque) to the level required during full-effort baseball pitching. A secondary purpose was to examine the kinematics produced during interval throwing compared to those seen during baseball pitching.

Study Design

Systematic Review.

Methods

Following PRISMA guidelines, PubMed, Embase, Web of Science, SPORTDiscus, and Google Scholar were systematically searched for biomechanical studies of flat-ground throwing and partial-effort pitching in baseball between 1987 and 2023. Studies that reported the biomechanics of either flat-ground throwing, or partial-effort pitching were included in this review. The AXIS tool was used to assess study quality.

Results

Thirteen articles met the inclusion criteria. Ten studies were determined to be of moderate quality, while three studies were deemed high quality. Elbow varus torque during partial-effort pitching was less than during full-effort pitching. Elbow varus torque for most flat-ground throws did not exceed full-effort pitching torque. While most studies showed increased elbow varus torque with increased flat-ground throwing distance, the distance at which elbow varus torque matched or exceeded full-effort pitching elbow varus torque was not consistent.As flat-ground throwing distance increased, shoulder external rotation angle and shoulder internal rotation velocity increased. Arm slot (forearm angle above horizontal) decreased as flat-ground throwing distance increased. For varied effort pitching, shoulder external rotation angle, shoulder internal rotation velocity, elbow extension velocity, and ball velocity increased as effort increased. While the front knee extended slightly from foot contact to ball release in full-effort pitching, the front knee flexed slightly during partial-effort pitching.

Conclusions

An interval throwing program progressively builds elbow varus torque up to levels produced in full-effort baseball pitching. While differences exist between interval throwing kinematics and pitching kinematics, the patterns are similar in general.

Level of Evidence

2.

Shoulder vibratory exercises improves shoulder external rotation muscle strength and shoulder function: Randomized comparison trial

BACKGROUND

Based on electromyography measurements, shoulder vibratory exercises efficiently stimulate shoulder muscles activity. Yet very few studies have supported that shoulder vibratory exercises increased shoulder muscles strength and function, and the noninferiority compared with conventional elastic resistance exercises remains unknown.

OBJECTIVE

This study investigated the effect of vibratory exercises versus conventional elastic resistance exercises with elastic bands on shoulder external rotation muscles strength and functional performance in young adults.

METHODS

26 young adults (7 males and 19 females, with age 23.89 ± 3.02) were recruited and randomly allocated to shoulder vibratory exercises with FLEXI-BAR (FLEXI-BAR group) or conventional resistance exercises with elastic band (TheraBand group) for 3 times/week, 4 weeks totally. Shoulder external rotator muscles strength test and Underkofler softball distance throw test (USDTT) were performed before and after the training period.

RESULTS

After 4 weeks training, shoulder external rotator muscles strength increased 22.25 ± 15.06 N (P= 0.004, effect size = 1.48) within FLEXI-BAR group and 22.81 ± 14.94 N (P= 0.007, effect size = 1.53) within TheraBand group. There were no statistically significant differences between groups in the three muscle strength tests (P> 0.65). Regarding shoulder function, FLEXI-BAR exercises increased the throw distance 0.81 ± 0.92 meters in USDTT (P= 0.041, effect size = 0.88) while TheraBand exercise did not (P= 0.284), yet there was no statistically significant between group effects (P= 0.608).

CONCLUSIONS

These findings suggest that shoulder vibratory exercises can improve shoulder muscles strength in young adults and can be a useful alternative to the conventional elastic resistance exercises to improve the shoulder muscles strength and function. This provides therapists with more options in terms of choosing training equipment for rehabilitation programs.

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.

The Use of Wearable Sensors for Preventing, Assessing, and Informing Recovery from Sport-Related Musculoskeletal Injuries: A Systematic Scoping Review

Wearable technologies are often indicated as tools that can enable the in-field collection of quantitative biomechanical data, unobtrusively, for extended periods of time, and with few spatial limitations. Despite many claims about their potential for impact in the area of injury prevention and management, there seems to be little attention to grounding this potential in biomechanical research linking quantities from wearables to musculoskeletal injuries, and to assessing the readiness of these biomechanical approaches for being implemented in real practice. We performed a systematic scoping review to characterise and critically analyse the state of the art of research using wearable technologies to study musculoskeletal injuries in sport from a biomechanical perspective. A total of 4952 articles were retrieved from the Web of Science, Scopus, and PubMed databases; 165 were included. Multiple study features-such as research design, scope, experimental settings, and applied context-were summarised and assessed. We also proposed an injury-research readiness classification tool to gauge the maturity of biomechanical approaches using wearables. Five main conclusions emerged from this review, which we used as a springboard to propose guidelines and good practices for future research and dissemination in the field.

Squatting Throwing Is Not Associated With Increased Medial Elbow Torque in Youth Baseball Catchers

PURPOSE

To compare medial elbow stress during squatting throwing, standing throwing, and maximum effort throwing and to analyze its relationships with throwing variables and the hip joint internal rotation (IR) range of motion (ROM) in youth baseball catchers.

METHODS

Forty-five youth baseball catchers were recruited. Exclusion criteria included pain during throwing, history of surgery, or upper-extremity injuries within 12 months. Catchers performed 5 throws for each of the following throwing conditions: squatting throwing, standing throwing, and maximum effort throwing. Catchers were outfitted with a wearable sensor sleeve that recorded the medial elbow torque, arm speed, and shoulder rotation. Ball velocity was measured using a radar gun.

RESULTS

Final analysis included 42 catchers (mean age, 11.5 ± 1.2 years; mean catcher experience, 16.7 ± 10.3 months). The medial elbow torque was significantly greater during maximum effort throwing (19.0 ± 5.2 Nm) than during squatting throwing (14.3 ± 5.4 Nm) and standing throwing (15.7 ± 4.7 Nm) (both P < .001); there was no significant difference between squatting throwing and standing throwing. Multiple linear regression analysis showed that the ball velocity was significantly positively associated with the medial elbow torque during squatting throwing and standing throwing (P = .023 and P = .029, respectively). During squatting throwing, the hip IR ROM on the throwing side was significantly negatively associated with the medial elbow torque (P = .011).

CONCLUSIONS

The medial elbow torque during squatting throwing was equivalent to that during standing throwing. Increased medial elbow torque was associated with greater ball velocity during squatting throwing and standing throwing and with decreasing hip joint IR ROM on the throwing side during squatting throwing. Evaluation and stretching of the hip joint IR ROM on the throwing side may be important to decrease elbow stress during squatting throwing in youth baseball catchers.

LEVEL OF EVIDENCE

Level II, prospective comparative observational trial.

Biomechanical Analysis of the Throwing Athlete and Its Impact on Return to Sport

Throwing sports remain a popular pastime and frequent source of musculoskeletal injuries, particularly those involving the shoulder and elbow. Biomechanical analyses of throwing athletes have identified pathomechanic factors that predispose throwers to injury or poor performance. These factors, or key performance indicators, are an ongoing topic of research, with the goals of improved injury prediction, prevention, and rehabilitation. Important key performance indicators in the literature to date include shoulder and elbow torque, shoulder rotation, kinetic chain function (as measured by trunk rotation timing and hip-shoulder separation), and lower-extremity mechanics (including stride characteristics). The current gold standard for biomechanical analysis of the throwing athlete involves marker-based 3-dimensional) video motion capture. Emerging technologies such as marker-less motion capture, wearable technology, and machine learning have the potential to further refine our understanding. This review will discuss the biomechanics of throwing, with particular attention to baseball pitching, while also delineating methods of modern throwing analysis, implications for clinical orthopaedic practice, and future areas of research interest.

Level of Evidence

V, expert opinion.

The Science and Biomechanics of Long-Toss

PURPOSE OF REVIEW

Overhead throwing is a particularly violent motion that requires a complex sequence of timed muscle activations to efficiently transfer energy up the kinetic chain to throw a ball. Long-toss has long been utilized as a means of increasing shoulder range of motion, strength, and endurance, as well as an important component of rehabilitation in interval throwing programs. The purpose of this review is to assess the current literature on the science and biomechanics of long-toss.

RECENT FINDINGS

While long-toss is ubiquitously utilized in throwing programs for pitchers of all ages, the definition of long-toss, as well as its primary function in a throwing program, is debated. Throwing biomechanics in long-toss differ from that of mound pitching, although much of the variation is determined by the type of long-toss: shorter distance and on a line versus maximum distance and not on a line. Biomechanical factors including the kinematic changes of increased maximum glenohumeral external rotation, increased maximum elbow flexion, decreased trunk forward flexion at front foot contact, kinetic changes of increased shoulder internal rotation torque, increased elbow varus torque, and increased elbow extension velocity can occur with maximum distance long-toss throwing. Long-toss is a highly variable training supplement that is used in throwing programs at all levels of baseball competition. Current literature has demonstrated a number of kinetic and kinematic changes in the throwing arm and throwing motion related to increasing long-toss distances. However, the exact benefits of long-toss are difficult to quantify due to the numerous definitions and various utilizations of long-toss.

Rehabilitation Following Ulnar Collateral Ligament Reconstruction in Overhead-Throwing Athletes

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The prevalence of ulnar collateral ligament (UCL) injury and UCL reconstruction (UCL-R) continues to rise, causing morbidity in overhead-throwing athletes.

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Postoperative rehabilitation protocols are essential for proper healing of the reconstructed ligament and safely returning athletes to competition, yet there is no uniformly accepted standard of care.

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UCL-R rehabilitation has traditionally been guided by expert opinion and conventional wisdom rather than scientific studies, resulting in substantial variability in rehabilitation practices, time to return to play, and outcomes.

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Current research efforts aim to closely investigate the biomechanical implications of UCL-R and overhead throwing to better guide rehabilitation and to improve competitive performance and outcomes.

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Additional biomechanical and scientific studies on rehabilitation modalities and timing are warranted for systematic analysis, optimization, and standardization of UCL-R rehabilitation.

Measuring 3D In-vivo Shoulder Kinematics using Biplanar Videoradiography

The shoulder is one of the human body's most complex joint systems, with motion occurring through the coordinated actions of four individual joints, multiple ligaments, and approximately 20 muscles. Unfortunately, shoulder pathologies (e.g., rotator cuff tears, joint dislocations, arthritis) are common, resulting in substantial pain, disability, and decreased quality of life. The specific etiology for many of these pathologic conditions is not fully understood, but it is generally accepted that shoulder pathology is often associated with altered joint motion. Unfortunately, measuring shoulder motion with the necessary level of accuracy to investigate motion-based hypotheses is not trivial. However, radiographic-based motion measurement techniques have provided the advancement necessary to investigate motion-based hypotheses and provide a mechanistic understanding of shoulder function. Thus, the purpose of this article is to describe the approaches for measuring shoulder motion using a custom biplanar videoradiography system. The specific objectives of this article are to describe the protocols to acquire biplanar videoradiographic images of the shoulder complex, acquire CT scans, develop 3D bone models, locate anatomical landmarks, track the position and orientation of the humerus, scapula, and torso from the biplanar radiographic images, and calculate the kinematic outcome measures. In addition, the article will describe special considerations unique to the shoulder when measuring joint kinematics using this approach.

Elbow Torque Is Reduced in Asymptomatic College Pitchers With Elbow Laxity: A Dynamic Ultrasound Study

PURPOSE

To determine the relation between medial elbow torque, as measured by wearable sensor technology, and adaptations of the medial elbow structures on dynamic ultrasound imaging in asymptomatic collegiate pitchers.

METHODS

Thirty-four pitchers from National Collegiate Athletic Association Division II universities were eligible for preseason testing. The exclusion criteria included age younger than 18 years, history of surgery, non-pitcher, or current restrictions. Pitchers were fitted with a wearable sensor sleeve that recorded elbow torque, arm slot, arm speed, and arm rotation. Pitchers threw 5 fastballs in a standardized manner off the mound at game-speed effort. They also underwent dynamic ultrasound imaging of the elbow by a musculoskeletal sonographer, with standardized valgus loading. Images were deidentified, and measurements of the ulnar collateral ligament (UCL) and ulnohumeral joint space (UHJS), to assess elbow laxity, were performed by a musculoskeletal radiologist.

RESULTS

The final analysis included 28 pitchers with an average age of 20.1 years (standard deviation, 1.3 years; range, 18-23 years) and playing experience of 15.3 years (standard deviation, 1.8 years; range, 11-19 years). The dominant UCL thickness (P < .001), loaded UHJS (P = .039), and delta UHJS (P < .001) were significantly greater than the nondominant measurements. An inverse correlation was found between loaded UHJS and medial elbow torque (r = -0.4, P < .001). Additionally, every 1-mm increase in UHJS significantly reduced medial elbow torque by 2.27 Nm (P = .032) and arm slot by 8.8° (P = .019) and increased arm rotation by 5.3° (P = .043). Pitchers with a loaded UHJS of 4.4 mm or greater and delta UHJS of 1.25 mm or greater had significantly reduced medial elbow torque (P < .001). Pitchers with a UCL thickness of 1.65 mm or greater had significantly increased medial elbow torque (47.4 Nm vs 44.8 Nm, P = .006).

CONCLUSIONS

Pitchers with increased dynamic elbow laxity were found to experience reduced medial elbow torque while pitching. Additionally, pitchers with greater UCL thickness on ultrasound were found to experience increased medial elbow torque while pitching. This study's findings suggest a relation between anatomic adaptations found on ultrasound of the pitching elbow and medial elbow torque.

LEVEL OF EVIDENCE

Level II, prospective cohort study.

The Effect of Straight-Line Long-Toss Versus Ultra-Long-Toss Throwing on Passive Glenohumeral Range of Motion Recovery After Pitching

BACKGROUND

Repetitive throwing in baseball pitchers can lead to pathologic changes in shoulder anatomy, range of motion (notably glenohumeral internal rotation deficit), and subsequent injury; however, the ideal strengthening, recovery, and maintenance protocol of the throwing shoulder in baseball remains unclear. Two strategies for throwing shoulder recovery from pitching are straight-line long-toss (SLT) throwing and ultra-long-toss (ULT) throwing, although neither is preferentially supported by empirical data.

HYPOTHESIS

ULT will be more effective in returning baseline internal rotation as compared with SLT in collegiate pitchers after a pitching session.

STUDY DESIGN

Cohort study.

LEVEL OF EVIDENCE

Level 3.

METHODS

A total of 24 National Collegiate Athletic Association Division I baseball pitchers with mean age 20.0 ± 1.1 years were randomized to either the ULT group (n = 13; 9 right-hand dominant, 4 left-hand dominant) or SLT group (n = 11; 10 right-hand dominant, 1 left-hand dominant). Measurements (dominant and nondominant, 90° abducted external rotation [ER], internal rotation [IR], and total range of motion [TROM]) were taken at 5 time points across 3 days: before and immediately after a standardized bullpen session on day 1; before and immediately after a randomized standardized ULT or SLT session on day 2; and before practice on Day 3.

RESULTS

ULT demonstrated significantly greater final ER compared with baseline (+10°; P = 0.05), but did not demonstrate significant IR changes. Similarly, SLT demonstrated significantly greater post-SLT ER (+12°; P = 0.02) and TROM (+12°;P = 0.01) compared with baseline, but no significant IR changes. Final ER measurements were similar between ULT (135° ± 14°) and SLT (138° ± 10°) (P = 0.59). There was also no statistically significant difference in final IR between ULT (51° ± 14°) and SLT (56° ± 8°) (P = 0.27).

CONCLUSION

The routine use of postperformance, ULT throwing to recover from range of motion alterations, specifically IR loss, after a pitching session is not superior to standard, SLT throwing. Based on these findings, the choice of postpitching recovery throwing could be player specific based on experience and comfort.

CLINICAL RELEVANCE

The most effective throwing regimens for enhancing performance and reducing residual impairment are unclear, and ideal recovery and maintenance protocols are frequently debated with little supporting data. Two strategies for throwing shoulder recovery from pitching are SLT and ULT throwing. These are employed to help maintain range of motion and limit IR loss in pitchers. The routine use of ULT throwing for recovery and to limit range of motion alterations after a pitching session is not superior to SLT throwing.

The Effect of the Crow Hop on Elbow Stress During an Interval Throwing Program

BACKGROUND

Postoperative rehabilitation protocols after ulnar collateral ligament (UCL) reconstruction typically involve a structured interval throwing program. In an effort to minimize torque placed on the UCL, athletes are often instructed to throw with a crow hop, even at short throwing distances. However, the effect of the crow hop on medial elbow stress is unknown.

PURPOSE/HYPOTHESIS

The purpose was to determine whether elbow stress differs with and without a crow hop across the throwing distances of a typical interval throwing program. We hypothesized that crow hop throws would generate lower torque on the elbow than standing throws at each distance of the interval throwing program.

STUDY DESIGN

Controlled laboratory study.

METHODS

Healthy high school and collegiate pitchers and position players were recruited from the surrounding area. Each player was outfitted with a wearable athletic sleeve and device that recorded elbow torque (Newton-meters), arm slot (degrees), arm speed (revolutions per minute), and shoulder rotation (degrees). Ball velocity (miles per hour) was measured using a radar gun. Players were instructed to perform 3 crow hop throws and 3 standing throws at distances of 30, 45, 60, 90, 120, 150, and 180 feet. A repeated measures analysis of variance was used to compare ball velocity, elbow torque, arm slot, arm speed, and shoulder rotation between crow hop and standing throws at each throwing distance.

RESULTS

Twenty athletes participated in this study (average age, 17.8 years; range, 15-25 years). The average medial elbow torque increased at each distance for both crow hop and standing throws at distances of 30, 45, 60, and 90 feet (P < .05), after which there were no significant increases in elbow torque (P > .05). The average torque was higher for crow hop throws than standing throws at distances of 30 feet (13.9 N·m vs 12.0 N·m; P = .002), 45 feet (21.8 N·m vs 19.3 N·m; P = .005), and 60 feet (28.0 N·m vs 24.5 N·m; P = .02).

CONCLUSION

Crow hop throws generated greater medial elbow torque than standing throws at distances up to 60 feet; however, there were no differences in elbow torque at distances greater than 60 feet between the 2 throw types. For both crow hop and standing throws, elbow stress increased at each distance interval up to 90 feet before plateauing at distances greater than 90 feet. The crow hop throwing technique does not reduce medial elbow stress during a simulated interval throwing program, and it may actually increase torque at shorter throwing distances.

CLINICAL RELEVANCE

The results of our study indicate that it would be prudent for players to initially perform standing throws at shorter distances and only later be allowed to employ a natural crow hop at greater distances to minimize torque placed on the medial elbow during UCL rehabilitation protocols.

Quantifying Throw Counts and Intensities Throughout a Season in Youth Baseball Players: A Pilot Study

Overuse injuries in youth baseball players due to throwing are at an all-time high. Traditional methods of tracking player throwing load only count in-game pitches and therefore leave many throws unaccounted for. Miniature wearable inertial sensors can be used to capture motion data outside of the lab in a field setting. The objective of this study was to develop a protocol and algorithms to detect throws and classify throw intensity in youth baseball athletes using a single, upper arm-mounted inertial sensor. Eleven participants from a youth baseball team were recruited to participate in the study. Each participant was given an inertial measurement unit (IMU) and was instructed to wear the sensor during any baseball activity for the duration of a summer season of baseball. A throw identification algorithm was developed using data from a controlled data collection trial. In this report, we present the throw identification algorithm used to identify over 17,000 throws during the 2-month duration of the study. Data from a second controlled experiment were used to build a support vector machine model to classify throw intensity. Using this classification algorithm, throws from all participants were classified as being “low,” “medium,” or “high” intensity. The results demonstrate that there is value in using sensors to count every throw an athlete makes when assessing throwing load, not just in-game pitches.

Effects of Mound Versus Flat-Ground Pitching and Distance on Arm Mechanics and Elbow Torque in High School Pitchers

Background:

Although the monitoring of a pitcher’s throwing arm workload has become a hot topic in both research and the pitching world, the impact of mound height and distance still remains unclear.

Purpose:

To compare the kinetics and kinematics between pitches from a mound and flat ground at 2 different distances.

Study Design:

Descriptive laboratory study.

Methods:

A total of 21 healthy high school varsity baseball pitchers (age, 16.2 ± 1.3 years; weight, 73.6 ± 11.0 kg; height, 181.3 ± 6.4 cm) participated in this study. Players were fitted with a motusBASEBALL sensor and sleeve. Each pitcher was instructed to pitch 5 fastballs under 4 conditions: mound at 60.5 ft (regulation distance), flat ground at 60.5 ft, mound at 50.5 ft, and flat ground at 50.5 ft. Linear mixed-effects models were used to account for both intra- and interplayer variability. A multivariable model was used to evaluate the association of mound pitching, flat-ground pitching, and their distances (50.5 ft and 60.5 ft), and their interaction to arm speed, arm slot, arm rotation, elbow varus torque, and ball velocity.

Results:

There were no statistically significant effects of mound, flat-ground, or distance variation on arm speed or shoulder rotation. Arm slot was significantly higher (+3.0°; P = .02) on pitches from the mound at 60.5 ft compared with 50.5 ft. Elbow varus torque was lower (–1.5 N·m; P = .02) on mound pitches at 60.5 ft compared with 50.5 ft. Pitches thrown from the mound displayed significantly faster ball velocity compared with flat-ground pitches at both distances (P < .01 for both), with pitches at 60.5 ft having higher velocity (+0.7 m/s; P < .01).

Conclusion:

Contrary to long-standing notions, the study results suggest that pitching from the mound does not significantly increase stress on the elbow compared with flat-ground pitching. Lower elbow varus torque and faster ball velocity at the regulation distance compared with the reduced distance indicate that elbow stress and ball velocity may not correlate perfectly, and radar guns may not be an appropriate surrogate measure of elbow varus torque.

Clinical Relevance:

A better understanding of the kinetic and kinematic implications of various throwing programs will allow for the designing of programs that are driven by objective data with aims directed toward injury prevention and rehabilitation in baseball pitchers.

Technology Used in the Prevention and Treatment of Shoulder and Elbow Injuries in the Overhead Athlete

PURPOSE OF REVIEW

To review the current technology available for the prevention and treatment of shoulder and elbow injuries in the overhead athlete.

RECENT FINDINGS

Shoulder and elbow injuries are common in recreational and high-level overhead athletes. Injury prevention in these athletes include identifying modifiable risk factors, offering effective preventative training programs, and establishing safe return-to-sport criteria. The advent and use of technologies and wearable devices with concomitant development of software and data analytic programs has significantly changed the role of sports technology in injury identification and prevention. Over the last few decades, leveraging new technologies to better understand and treat patients has become an increasing focus of healthcare. Technologies currently being applied to the treatment of the overhead athlete include kinesiotaping, heart rate monitors, accelerometers/gyroscopes, dynamometers/force plates, camera-based monitoring systems (optical motion analysis), and inertial sensor monitoring units. Advances in technology have made it possible to acquire large amounts of data on athletes that may be used to guide treatment and injury prevention programs; however, literature validating the clinical efficacy of many of these technologies is limited. Further research is needed to continue to allow team physicians to provide better, cost-efficient, and individualized care to the overhead athlete using technology.

Importance of radar gun inclusion during return-to-throwing rehabilitation following ulnar collateral ligament reconstruction in baseball pitchers: a simulation study

BACKGROUND

Rehabilitation following elbow ulnar collateral ligament reconstruction in baseball pitchers relies on a progression of pitching activities to ensure protection and gradual strengthening of the reconstructed ligament. The purpose of this study was to determine the medial elbow torque associated with pitches at various effort levels and determine whether radar gun assistance improves players' abilities to accurately match partial-effort pitches with true references based on maximum pitch velocity.

METHODS

Thirty-seven healthy high school and collegiate baseball pitchers were included in this study. Participants were excluded if they were injured, recovering from injury, or otherwise not currently pitching at full effort. Pitch parameters were collected using a validated wearable sensor. Participants threw 5 pitches at 50%, 75%, and 100% subjective effort. Pitchers then threw 5 pitches at 50% maximum velocity and 75% maximum velocity, as measured by a radar gun.

RESULTS

Thirty-seven pitchers completed this study. Pitches thrown at 50% and 75% partial effort were significantly faster and generated higher elbow torque than did pitches thrown at 50% and 75% velocity, respectively (P < .001). A 10% decrease in percentage of maximum velocity was associated with a 13% decrease in percentage of maximum elbow torque (β coefficient = 1.3, R² = 0.81, P < .001).

CONCLUSION

Pitchers generate higher-than-intended forces when throwing at 50% and 75% effort during a subjective partial-effort throwing protocol. Use of a radar gun to guide partial-effort throwing during throwing rehabilitation programs may protect the reconstructed elbow from excess medial torque.

Predictors of elbow torque among professional baseball pitchers

BACKGROUND

Overuse injuries of the shoulder and elbow continue to be prevalent in elite baseball pitchers. Pitch velocity has been shown to impact medial elbow torque in adolescent baseball pitchers. However, the determinants of medial elbow torque in professional baseball pitchers are not known.

PURPOSE

To determine the influence of pitch type, velocity, and player characteristics on medial elbow torque in professional baseball pitchers.

METHODS

Professional baseball pitchers were recruited for participation. Height, weight, body mass index (BMI), and throwing arm measurements were obtained for all study participants. While wearing a gyroscopic sensor equipped with an accelerometer, participants were instructed to throw a standard, randomized sequence of fastballs, changeups, and curveballs. Elbow torque, arm slot, arm speed, shoulder rotation, and ball velocity were recorded for each pitch. A linear mixed model was used to evaluate the association of pitch type with each pitch parameter, adjusting for pitchers' demographics.

RESULTS

A total of 12 professional baseball pitchers were included in this study. Among the pitch types, medial elbow torque was significantly higher in fastballs than in curveballs (P = .001). An increased BMI value was independently associated with decreased elbow torque in pitchers (P = .035).

CONCLUSION

Fastballs place significantly higher torque on the medial elbow than do curveballs, which is consistent with previous studies done on high school and collegiate populations. Pitchers with a higher BMI experience significantly less torque across the medial elbow.