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Dines, Joshua S.

https://orcid.org/0000-0002-2135-9317

Mayo Clinic

Hospital for Special Surgery

Citations 38

Elbow Ulnar Collateral Ligament Injuries: Indications, Management, and Outcomes
Carr, James, Camp, Christopher L. , Dines, Joshua S. , Camp, Christopher L. , Carr, James B.

Arthroscopy | February 26, 2020 | Volume: 36 | Issue: 5 | Pages: 1221-1222

10.1016/j.arthro.2020.02.022 Get It

Ulnar collateral ligament (UCL) injuries continue to be a major source of morbidity in baseball players. The throwing motion creates nearly supraphysiological levels of valgus stress on the medial elbow, placing these athletes at high risk of UCL injury. The incidence of injury continues to rise at an alarming rate, especially among adolescent baseball pitchers. Certain risk factors for UCL injury have been identified, including pitch velocity, fewer days between outings, and overall workload. Treatment of UCL injuries depends on the type of tear. Low‐ to medium‐grade partial UCL tears (i.e., grade I or II tears) are usually amenable to a period of rest and a graduated throwing program. Recently, platelet‐rich plasma has been described as another treatment modality to consider in a throwing athlete with a partial UCL tear, although robust clinical data are currently lacking. Most athletes can return to competitive throwing in 3 to 4 months after nonoperative management of a low‐grade partial UCL tear. Indications for surgical management of a UCL injury are a complete (type III) tear or failure of extensive conservative management after a partial UCL tear. UCL reconstruction remains the gold standard for operative management of a complete UCL tear. Both the modified Jobe technique and the docking technique have shown excellent results with return‐to‐play rates between 80% and 90%. Recently, UCL repair with collagen‐dipped suture tape augmentation has gained some popularity. However, long‐term results are lacking, especially in elite athletes. Time to return to play after UCL reconstruction is variable. Most athletes return to full competition in 12 to 15 months, although professional pitchers often require 15 to 18 months to return to their previous level of competition. Revision rates remain low (1%‐7%), yet the revision rate is expected to rise as the number of UCL reconstructions performed in the United States continues to increase.
Upper Extremity and Hip Range of Motion Changes Throughout a Season in Professional Baseball Players
Chan, Justin M., Zajac, John M., Altchek, David W. , Coleman, Struan H. , Camp, Christopher, Erickson, Brandon J. , Camp, Christopher L. , Dines, Joshua S.

The American Journal of Sports Medicine | December 31, 2019 | Volume: 48 | Issue: 2 | Pages: 481-487

10.1177/0363546519894567 Get It

Background: Loss of upper and lower extremity range of motion (ROM) is a significant risk factor for injuries in professional baseball players. Purpose/Hypothesis: The purpose was to determine changes in ROM in professional baseball players over the course of a single season and their careers. We hypothesized that pitchers and position players would lose ROM, specifically total shoulder motion (total ROM [TROM]) and hip internal rotation (IR), over the course of a season and their careers. Study Design: Case series; Level of evidence, 4. Methods: Upper and lower extremity ROM measurements were recorded during pre-, mid-, and postseason on all professional baseball players for a single organization between 2011 and 2018. ROM measurements were compared for pitchers and position players over the course of the season and their careers. Also, ROM measurements over the pre-, mid-, and postseason were compared between pitchers and position players. Results: A total of 166 professional baseball players (98 pitchers, 68 position players) were included. Pitcher hip external rotation (ER; P < .001), IR ( P = .010), and TROM ( P < .001) for lead and trail legs decreased over the course of the season. Pitcher shoulder ER ( P = .005), TROM ( P = .042), and horizontal adduction ( P < .001) significantly increased over the course of the season. Position player shoulder flexion ( P = .046), hip ER ( P < .001, lead leg; P < .001, trail leg), and hip TROM ( P = .001; P = .002) decreased over the course of the season. Position player shoulder ER ( P = .031) and humeral adduction ( P < .001) significantly increased over the course of the season. Over the course of pitchers’ careers, there was decreased shoulder IR ( P = .014), increased shoulder horizontal adduction ( P < .001), and hip IR ( P = .042) and hip TROM ( P = .027) for the lead leg. Position players experienced loss of hip TROM ( P = .010, lead leg; P = .018, trail leg) over the course of their careers. Pitchers started with and maintained more shoulder ER and gained more shoulder TROM over a season as compared with position players. Conclusion: Pitchers and position players saw overall decreases in hip ROM but increases in shoulder ROM over the course of the season and career.
Variability in Baseball Throwing Metrics During a Structured Long-Toss Program: Does One Size Fit All or Should Programs Be Individualized?
Leafblad, Nels D. , Conte, Stan, Fealy, Stephen A., D’Angelo, John , Larson, Dirk R. , Fleisig, Glenn S. , Dines, Joshua S. , Camp, Christopher L.

Sports Health: A Multidisciplinary Approach | September 3, 2019 | Volume: 11 | Issue: 6 | Pages: 535-542

10.1177/1941738119869945 Get It

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.
Do Professional Baseball Players With a Higher Valgus Carrying Angle Have an Increased Risk of Shoulder and Elbow Injuries?
Chalmers, Peter N. , Zajac, John M., Sgroi, Terrance , Eno, Jonathan-James , Altchek, David W. , Coleman, Struan H. , Zajac, John, Erickson, Brandon J. , Dines, Joshua S.

Orthopaedic Journal of Sports Medicine | August 27, 2019 | Volume: 7 | Issue: 8 | Pages: No page available

10.1177/2325967119866734 Get It

Background: There are many risk factors for shoulder and elbow injuries in professional baseball pitchers. The elbow carrying angle has not been studied as a potential risk factor. Purpose/Hypothesis: The aim of this study was to determine whether elbow carrying angle is a risk factor for shoulder or elbow injuries in professional baseball pitchers. We hypothesized that pitchers with a higher elbow carrying angle would be less likely to sustain an injury during the season than pitchers with a lower elbow carrying angle. Study Design: Cohort study; Level of evidence, 2. Methods: All professional pitchers for a single baseball club during the 2018 season had the carrying angle of both elbows measured at spring training by a single examiner. The pitchers were followed prospectively throughout the season. Shoulder and elbow injuries were recorded prospectively. Results: A total of 52 pitchers (21 [40%] Major League Baseball and 31 [60%] Minor League Baseball) were included. During the season, 23 (44%) pitchers became injured. The mean carrying angle in the throwing arm was 12.5° ± 4.2° versus 9.9° ± 2.8° in the nonthrowing arm ( P < .001). Comparing the injured and noninjured groups, there were no differences in level of play ( P = .870), throwing hand dominance ( P = .683), batting hand dominance ( P = .554), throwing-side carrying angle ( P = .373), nonthrowing-side carrying angle ( P = .773), or side-to-side difference in carrying angle ( P = .481). Conclusion: The elbow carrying angle was not associated with an injury risk during a single season in professional baseball pitchers.
Revision Ulnar Collateral Ligament Reconstruction in Professional Baseball: Current Trends, Surgical Techniques, and Outcomes
Desai, Vishal S. , Conte, Stan, Ciccotti, Michael C., Altchek, David W. , D’Angelo, John , Griffith, Timothy B. , Desai, Vishal , Camp, Christopher L. , Ahmad, Christopher S. , Dines, Joshua S. , Griffith, Timothy Bryan

Orthopaedic Journal of Sports Medicine | August 14, 2019 | Volume: 7 | Issue: 8 | Pages: No page available

10.1177/2325967119864104 Get It

Background: Ulnar collateral ligament (UCL) reconstruction of the elbow is commonly performed on professional baseball pitchers. Recent reports have suggested that revision rates are on the rise and may be higher than previously thought. Purpose: To provide a comprehensive report on current trends, surgical techniques, and outcomes of revision UCL reconstructions performed on professional baseball pitchers between 2010 and 2016. Study Design: Case series; Level of evidence, 4. Methods: The Major League Baseball Health and Injury Tracking System (HITS) was used to compile records of all revision UCL reconstructions performed on professional baseball pitchers between 2010 and 2016. Player data and outcomes were obtained from HITS, and surgical details were obtained from operative reports. Descriptive statistical analysis was performed on epidemiologic data. Outcomes (return to play [RTP] rates, RTP times, subsequent injuries, and subsequent surgeries) were compared across the most common surgical techniques (docking vs modified Jobe) and graft sources (palmaris longus autograft vs hamstring autograft). Results: A total of 69 professional baseball pitchers underwent revision UCL reconstruction from 2010 to 2016 at an average of 1424 days (47 months) after their primary surgery. A trend was seen toward increasing numbers of revision surgeries over time ( R 2 = 0.441; P = .104). The most commonly used tunnel configuration was the modified Jobe technique (n = 41; 59.4%), and the most commonly used graft was hamstring autograft (n = 34; 49.3%). A majority (76.6%) of pitchers achieved RTP, and 55.3% were able to return to the same level of play. Mean time to RTP was 436 days (14.5 months) for players with a palmaris longus autograft versus 540 days (18 months) for those with a hamstring autograft ( P = .108). Further, the mean time to RTP was 423 days (14 months) for the docking technique versus 519 days (17 months) for the modified Jobe technique ( P = .296). Similar rates of subsequent injuries and surgeries were noted between the 2 revision techniques and 2 most commonly used graft constructs. Conclusion: Revision UCL reconstruction showed relatively high RTP rates (77%), but only 55% of players returned to their same level of play. Mean time to RTP was shorter than that found in other, smaller investigations. Although general trends were seen toward decreased time to RTP for the docking technique and palmaris longus autograft, these differences did not reach statistical significance.
Variability in Baseball Throwing Metrics During A Structured Long-toss Program: Does One Size Fit All?
Leafblad, Nels D. , Conte, Stan, Fealy, Stephen, D’Angelo, John , Larson, Dirk R. , Fleisig, Glenn S. , Dines, Joshua S. , Camp, Christopher L.

Orthopaedic Journal of Sports Medicine | July 29, 2019 | Volume: 7 | Issue: 7_suppl5 | Pages: No page available

10.1177/2325967119s00394 Get It

Objectives: The variability of throwing metrics, particularly elbow torque and ball velocity, during structured long-toss programs is yet to be fully elucidated. The primary aims of this study were to assess various throwing metrics through a structured long-toss program using wearable technology and to quantify the intra and inter thrower variability of these metrics at each stage of throwing. Methods: This was a descriptive laboratory study in which 60 high school and collegiate pitchers participated in a predetermined, structured, progressive long-toss program. All players wore a motusBASEBALL sleeve (Motus Global, Inc.; Rockville Centre, NY), which measured arm slot, arm velocity, shoulder rotation, and elbow varus torque. Radar guns were used to measure ball velocity. These metrics were compared within and between all pitchers at each of the following throwing distances: 90 ft, 120 ft, 150 ft, 180 ft, and maximum effort mound pitching. Intra- and inter- thrower reliabilities were calculated for each throwing metric at every stage of the program. Excellent intra-thrower reliability was defined by an Intra-class coefficient (ICC) >0.750. Acceptable inter-thrower reliability was defined by a Coefficient of Variation (CV) <5%. Results: Ball velocity significantly changed at each progressive throwing distance, but this did not consistently correlate with an increase in elbow torque. Pitching from the mound did not place more torque on the elbow than throwing from 120 ft and beyond. Intra-thrower reliability was excellent throughout the progressive long-toss program for each throwing metric. Ninety-one percent of throwers had acceptable inter-thrower reliability for ball velocity, whereas only 79% of throwers had acceptable inter-thrower 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.
Does Perceived Effort Match Actual Measured Effort During Baseball Long Toss Programs?
Melugin, Heath P. , Conte, Stan, Fealy, Stephen, D’Angelo, John , Larson, Dirk R. , Fleisig, Glenn S. , Dines, Joshua S. , D’Angelo, John, Camp, Christopher L.

Orthopaedic Journal of Sports Medicine | July 29, 2019 | Volume: 7 | Issue: 7_suppl5 | Pages: No page available

10.1177/2325967119s00393 Get It

Objectives: Progressive throwing programs are a mainstay of rehabilitating the throwing athlete after injury or surgery. Athletes are commonly asked to throw at reduced levels of effort (i.e. “50% effort”, ”75%,” etc) to minimize stress to healing tissues. However, it is unknown whether players’ perceived exertion matches actual exertion. The purpose of this study was to determine whether decreased effort correlates with decreased throwing metrics, whether metrics decrease to a predictable degree, and to quantify variability of these metrics within a given athlete when attempting to throw at sub-maximal effort. Methods: Sixty healthy, high school and collegiate baseball pitchers participated in a structured throwing program. After warming up, each pitcher was asked to throw five, max effort long toss throws at a distance of 120 feet. Afterwards, they were asked to give 5 throws at both 75% effort and 50% effort from the same distance. A motusBASEBALL sleeve (Motus Global, Inc.; Massapequa, NY) was worn by all players, which measured arm slot, velocity, shoulder rotation, and elbow varus torque (Nm). Ball velocity was measured in miles per hour (MPH) using a radar gun. The observed changes in throwing metrics were compared to one another across each of the throwing scenarios using a general estimating equation to control for multiple comparisons. They were also compared to the expected change to see if a decrease from 100% effort to 75%, and then to 50% resulted in proportional decreases in elbow torque and ball velocity. Intra-thrower variability was determined for each throwing metric at each degree of effort, and these results are reported using intra-class correlation coefficients (ICC) where an ICC > 0.75 was considered to represent excellent agreement. Results: Mean elbow torque decreased as players decreased their perceived effort from 100% (72.7 Nm) to 75% (67.3 Nm) to 50% (62.s Nm) (p<0.001). Mean ball velocity also decreased as they progressed from 100% effort (77.8 MPH) to 75% effort (66.5) to 50% effort (60.3 MPH) throws (p<0.001). However, these observed decreases in torque and velocity were much smaller in magnitude than the decreases in perceived effort. During the 75% effort throws, torque and velocity were not reduced to 75% of max. Instead, elbow torque was only reduced to 93.3% of max, and velocity dropped to 86.1% of max. Similarly, for the 50% effort throws, torque remained 86.5% of max effort torque, while velocity remained 78.1% of max. Accordingly, for every 25% decrease in perceived effort, torque only decreased 7%, and velocity only decreased 11%. These observed differences were all significantly different than the expected differences (p<0.001 for all). Intra-thrower reliability was considered excellent for all metrics within each throwing scenario: max effort, 75% effort, and 50% effort (ICC>0.75 for all). Conclusion: Measured effort was significantly greater than perceived effort during this standardized throwing program for all metrics tested. This is especially true for ball velocity and varus elbow torque. Ultimately, 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. This has significant implications for throwers during the rehabilitation process as their elbows are likely experiencing more stress than desired. Clinicians and coaches must be aware and may want to consider transitioning to more objective measures of effort during rehabilition.
Flat Ground Throwing Results in Decreased Ball Velocity and Increased Elbow Torque Compared to Mound Throwing
Mcelheny, Kathryn, Ling, Daphne I. , Camp, Christopher L. , Dowling, Brittany , Dines, Joshua S.

Orthopaedic Journal of Sports Medicine | July 29, 2019 | Volume: 7 | Issue: 7_suppl5 | Pages: No page available

10.1177/2325967119s00364 Get It

Objectives: The incidence of shoulder and elbow overuse injury continues to rise in youth baseball players. Several throwing programs designed to reduce stress on the elbow have been described, but most are not evidence-based. The aim of this study was to compare the kinetics and kinematics between mound and flat-ground pitching at two different distances with the goal of developing evidenced-based injury prevention and recovery guidelines for youth throwers. Methods: Fifteen healthy, high school varsity-level baseball pitchers (mean age 16.7 ± 0.7 yrs; height 182.2 ± 6.2 cm; weight 76.0 ± 9.4 kg;) participated in the study. Players were fitted with a motusBASEBALLTM sensor and sleeve (Motus Global, Rockville Centre, NY), which has been shown to have good reliability and correlation with in-laboratory measures. Each pitcher was asked to pitch 5 fastballs to a catcher under each of the 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. For each pitch, the sensor recorded arm speed, arm slot, shoulder rotation, and elbow varus torque. Ball velocity was tracked with a radar gun (Stalker Radar, Richardson, TX). Linear mixed-effects models were used to account for both within and between-subject variability. A multivariable model was used to evaluate the association of mound pitching (vs flat ground), distance (50.5 vs 60.5 ft), and their interaction on each of the following outcomes: arm speed, arm slot, shoulder rotation, elbow varus torque, and ball velocity. Results: There were no statistically significant effects of mound vs flat ground or distance variation on both arm speed or shoulder rotation. Arm slot was significantly higher on pitches from the mound at 60.5 ft [+4.58 (95% CI: 1.26, 7.90), p=0.007]. Elbow varus torque was significantly lower on throws from the mound [-1.88 (95% CI: -3.56, -0.20), p=0.03] and from a longer distance [-2.21 (95% CI: -3.89, -0.53), p=0.01]. Pitches thrown from the mound were significantly faster compared to flat ground at both distances, with throws at 60.5 ft of greater velocity than at 50.5 ft [+1.03 (95% CI: 0.66, 1.40), p<0.001]. Please see the Table for full results. Conclusion: The findings suggest that throwing from the mound may not be higher risk compared to flat ground, contrary to long-standing notions. The lower elbow varus torque and higher arm slot, which has previously been shown to be associated with reduced stress, from throwing from the mound may even indicate a protective effect. Compared to 50.5 ft, there was lower elbow varus torque and faster ball velocity at the longer distance, indicating that elbow stress and ball velocity may not correlate perfectly, and radar guns may not be an appropriate surrogate measure of elbow varus torque. A better understanding of the kinetic and kinematic implications of various throwing programs will allow for designing programs that are based on objective data to achieve the goal of preventing injuries in young baseball players. [Table: see text]
Reconstruction of the Medial Ulnar Collateral Ligament of the Elbow: Biomechanical Comparison of a Novel Anatomic Technique to the Docking Technique
Bernard, Christopher D. , Benavitz, Bill, Konicek, John , Altchek, David W. , Dines, Joshua S. , Camp, Christopher L.

Orthopaedic Journal of Sports Medicine | July 17, 2019 | Volume: 7 | Issue: 7 | Pages: No page available

10.1177/2325967119857592 Get It

Background: In recent years, understanding of the anatomy of the ulnar collateral ligament (UCL) has evolved, demonstrating that the insertional footprint of the UCL on the ulna is more elongated and distally tapered than previously described. Current UCL reconstruction configurations do not typically re-create this native anatomy, which may represent a potential area for improvement. Purpose/Hypothesis: The purposes of this study were (1) to describe a novel anatomic UCL reconstruction technique designed to better replicate the native UCL anatomy and (2) to biomechanically compare this with the docking technique. The hypothesis was that the ultimate load to failure for the anatomic technique would not be inferior to the docking technique. Study Design: Controlled laboratory study. Methods: A total of 16 fresh-frozen cadaveric upper extremities (8 matched pairs) were utilized. One elbow in each pair was randomized to receive UCL reconstruction via the docking technique or the novel anatomic UCL reconstruction technique with palmaris tendon autograft. Following reconstruction, biomechanical testing was performed by applying valgus rotational torque at a constant rate of 5 deg/s until ultimate mechanical failure of the construct occurred. Maximal torque (N·m), rotation stiffness (N·m/deg), and mode/location of failure were recorded for each specimen. Results: The mean ultimate load to failure for elbows in the docking technique group was 23.8 ± 6.1 N·m, as compared with 31.9 ± 8.4 N·m in the anatomic technique group ( P = .045). Mean rotational stiffness was 1.9 ± 0.7 versus 2.3 ± 0.9 N·m/deg for the docking and anatomic groups, respectively ( P = .338). The most common mode of failure was suture pullout from the graft, which occurred in all 8 (100%) docking technique specimens and 7 of 8 (88%) specimens that underwent the anatomic UCL reconstruction technique. Conclusion: Ultimately, the anatomic UCL reconstruction technique demonstrated superior strength and resistance to valgus torque when compared with the docking technique, and this was comparable with that of the native UCL from prior studies. Increased initial strength may allow for earlier initiation of throwing postoperatively and potentially shorten return-to-play times. Clinical Relevance: Current UCL reconstruction techniques do not accurately reproduce the UCL insertional anatomy on the ulna. The novel anatomic technique described may result in more natural joint kinematics. This study demonstrated load-to-failure rates that are significantly higher than with the docking technique and consistent with the native ligament, as reported from previous studies. These findings may serve as a foundation for future clinical study and optimization of this technique.
Baseball Pitchers’ Perceived Effort Does Not Match Actual Measured Effort During a Structured Long-Toss Throwing Program
Melugin, Heath P. , Conte, Stan, Fealy, Stephen A., D’Angelo, John, Larson, Dirk R. , Fleisig, Glenn S. , Dines, Joshua S. , Camp, Christopher L.

The American Journal of Sports Medicine | May 31, 2019 | Volume: 47 | Issue: 8 | Pages: 1949-1954

10.1177/0363546519850560 Get It

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.