Abstrac
Introduction
Recently, star pitchers in Major League Baseball (MLB) have faced devastating elbow injuries, causing some to question whether implementation of the MLB pitch clock during the 2023 season has led to a higher rate of elbow injuries among pitchers. This study aims to determine if implementation of the MLB pitch clock in the 2023 MLB season affected the injury rate in pitchers.
Methods
Injury data was collected for the 2021, 2022, and 2023 MLB seasons using the fangraphs.com injury database. Incidence rate ratio was calculated to compare the injury rate for the 2023 season to the 2021 and 2022 seasons. A z-test for proportions was used to determine significance levels.
Results
The 2023 season showed a decrease in the rate of the total number of injuries when compared to the 2021 (P = 0.01) and 2022 (P = 0.02) seasons. There was no statistical difference in the rate of Tommy John Surgery, Flexor Tendon Injuries, or other cause elbow injuries.
Conclusion
Following implementation of the MLB pitch clock during the 2023 season, the total number of injuries decreased, but there was no change in the rate of elbow injuries in pitchers compared with the 2021 and 2022 MLB seasons. Future studies are needed to determine if the pitch clock has a longitudinal effect on injuries.
Keywords: Injury, Sports medicine, MLB, Pitch clock, Ulnar collateral ligament
Abbreviations
- AGE
Average Game Exposure
- ATP-CP
Adenosine Triphosphate-Creatine Phosphate
- IRR
Incidence Rate Ratio
- IR
Incidence Rate
- MLB
Major League Baseball
- UCL
Ulnar Collateral Ligament
1. Introduction
Injuries in professional sports can impact the performance of athletes, derail careers, and have significant monetary impacts on teams and players.1,2 Lately, sports media has paid significant attention to elbow injuries observed in star Major League Baseball (MLB) pitchers.1 This has led to a debate on whether implementation of a pitch clock during the 2023 season led to an increase in elbow injuries among pitchers.1 Pitchers face several common elbow injuries including elbow inflammation, flexor tendon injury, and ulnar collateral ligament (UCL) tears.3 UCL tears are the most feared due to the impact that it can have on a pitchers career. Despite major innovations in the repair of the UCL of the elbow (Internal Brace [Arthrex Inc., Naples, Florida]) and reconstruction of the UCL (Tommy John Surgery), return to pitching for MLB pitchers takes 12–16 months.4,5 This can result in significant professional, financial, and social challenges for pitchers.4, 5, 6 Given the impact an injury can have on MLB pitchers, investigation into the factors that have led to the perceived increase in injuries is paramount.
Many theories have been proposed to attempt to explain why pitchers are facing higher levels of elbow injuries. One theory is that increasing velocity8 and spin rates (2) are pushing the bounds of force that the elbow can physically handle.7 Another theory is that an increase in “sweeper” breaking balls caused an increase in injuries.9 Other theories include youth baseball pitching overuse,10,11 pitcher sticky substance use,2,12 or pitching biomechanics.7 Many of these theories have been explored, but have not shown evidence as the single factor for elbow injuries. The current hot-topic theory that some believe contributes to injuries is the implementation of the MLB pitch clock in the 2023 season.1
In 2023, MLB implemented a pitch clock to increase the pace of play of games.13 The pitch clock provides pitchers 15 s between pitches with no runners on base and 20 s between pitches with runners on base before they must deliver a pitch.13 When introduced in minor league baseball, it was hypothesized the pitch clock would lead to increased injuries due to decreased recovery time.14 Pitchers use fast, rapid movements relying on the Adenosine Triphosphate-Creatine Phosphate (ATP-CP) energy system.15 This system is roughly 50 % restored after 20 s and 87 % restored after 1 min.16 Theoretically, the pitch clock does not allow the necessary time for recovery of this energy system.14 This lack of recovery time could lead to muscular fatigue and increased forces upon a pitcher's ligaments and tendons.14
With the pitch clock factor and the rise of arm injuries in star players, urgent investigation is needed to determine if the pitch clock influences the injury rate in pitchers. This study aims to determine whether the pitch clock is leading to an increase in injuries in MLB pitchers. With the understanding of the energy systems used in baseball and length of the pitch clock, we hypothesize that the number of injuries experienced by MLB pitchers will increase following the institution of the pitch clock.
2. Materials and methods
2.1. Study design
Injury data was compiled from fangraphs.com injury report database,17 the primary source for MLB injury analysis in recent literature.18,19 Injury data was collected for the 2021, 2022, and 2023 MLB seasons. Seasons prior to 2021 were not included due to the 2020 season being shortened by COVID-19, leading to a rise in injuries.18,19 Injury timeframe was limited between opening day and the final day of the regular season to produce an accurate average game exposure. Illnesses and non–neuromusculoskeletal complaints were excluded, as injuries are physical complaints.20 Data was compiled into major anatomical categories and subgroup categories.
2.2. Data analysis
Data analysis followed methods of recent MLB injury analysis studies.18,19,21 The incidence ratio (IR) was calculated for each category, using the average game exposure (AGE) per 1000 athletes.18,19,21 Average game exposure was calculated by multiplying the number of pitchers on the roster (13), the total games played in the season (162), and the number of teams (30), consistent with recent literature.18,19,22 This created an average game exposure of 63,180. Incidence ratio was calculated by dividing the number of injuries by the average game exposure, and multiplying by 1000, similarly to previous literature.18,19 Incidence rate ratio (IRR) was created to compare the 2023 season versus each of the 2021 and 2022 seasons by dividing the incidence rate of the 2023 season by the incidence rate of the season of comparison, consistent with previous literature.18,19 95 % confidence intervals and p-values were calculated. Z-test for proportions was used to calculate the p-values, consistent with recent literature.18,19
3. Results
3.1. Total number of injuries
The total number of injuries was 467, 461 and 393 for the 2021, 2022, and 2023 seasons, respectively. The highest total of elbow and forearm injuries came during the 2023 season. The highest total of Tommy John Surgeries came during the 2022 season. See Table 1.
Table 1.
Total number of injuries by category.
| Major Anatomical Categories | 2021 | 2022 | 2023 |
|---|---|---|---|
| Total Injuries | 467 | 461 | 393 |
| Upper Extremity | 269 | 233 | 232 |
| Lower Extremity | 104 | 87 | 80 |
| Head/Neck | 13 | 13 | 12 |
| Torso | 75 | 78 | 64 |
| Undisclosed | 6 | 50 | 5 |
| Subgroup Anatomical Categories | |||
| Elbow/Forearm | 107 | 109 | 122 |
| Shoulder | 103 | 87 | 76 |
| Groin/Quad | 24 | 16 | 7 |
| Hamstring | 24 | 12 | 19 |
| Knee | 19 | 17 | 15 |
| Foot/Ankle | 18 | 16 | 13 |
| Torso | 75 | 89 | 64 |
| Head/Neck | 13 | 13 | 12 |
| Calf/Lower Leg/Shin | 11 | 12 | 13 |
| Biceps/Triceps | 18 | 16 | 21 |
| Hand/Wrist | 41 | 21 | 13 |
| Hip/Glute | 8 | 14 | 13 |
| Elbow Specific Category | |||
| Tommy John | 20 | 30 | 27 |
| Flexor Tendon Injury | 37 | 33 | 36 |
| Other Elbow | 50 | 46 | 59 |
3.2. Major anatomical categories
Comparison of the 2023 versus 2021 seasons revealed a statistically significant decrease in the total number of injuries for the 2023 season (P = 0.01). Comparison of the 2023 vs. 2022 seasons revealed a statistically significant decrease in the total number of injuries (P = 0.02) and number of undisclosed injuries (P < 0.001) for the 2023 season. There was no significant change in injuries for the 2023 against the 2021 and 2022 seasons for the remaining categories. See Table 2.
Table 2.
Major anatomical category injury analysis for the 2021 and 2022 seasons versus the 2023 MLB pitch clock season (IRR, Incidence rate ratio; IR, Incidence Rate).
| Injuries | 2021 IR | 2022 IR | 2023 IR | IRR 2023 vs. 2021 (95 % CI) | P-Value | IRR 2023 vs. 2022 (95 % CI) | P-Value |
|---|---|---|---|---|---|---|---|
| Total | 7.39 | 7.30 | 6.22 | 0.84 (0.74, 0.96) | 0.01 | 0.85 (0.75, 0.98) | 0.02 |
| Upper Extremity | 4.26 | 3.69 | 3.67 | 0.86 (0.72, 1.03) | 0.10 | 1 (0.83, 1.19) | 0.96 |
| Lower Extremity | 1.65 | 1.38 | 1.27 | 0.77 (0.57, 1.03) | 0.08 | 0.92 (0.68, 1.25) | 0.59 |
| Head/Neck | 0.21 | 0.21 | 0.19 | 0.92 (0.42, 2.02) | 0.84 | 0.92 (0.42, 2.02) | 0.84 |
| Torso | 1.19 | 1.23 | 1.01 | 0.85 (0.61, 1.19) | 0.35 | 0.82 (0.59, 1.14) | 0.24 |
| Undisclosed | 0.09 | 0.79 | 0.08 | 0.83 (0.25, 2.73) | 0.76 | 0.1 (0.04, 0.25) | <0.001 |
3.3. Anatomic subgroups
In comparing anatomical subgroups for the 2023 and 2021 seasons, significant decreases were observed in the shoulder (P = 0.04), groin and quad (P < 0.001), and hand and wrist (P < 0.001) injuries for the 2023 season. Torso injuries also decreased significantly (P = 0.04) in 2023. No significant changes were found (P > 0.05) in the remaining groups. See Table 3.
Table 3.
Anatomical subgroup injury analysis for the 2021 and 2022 seasons versus the 2023 MLB pitch clock season (IRR, Incidence rate ratio; IR, Incidence Rate).
| Injuries | 2021 IR | 2022 IR | 2023 IR | IRR 2023 vs. 2021 (95 % CI) | P-Value | IRR 2023 vs. 2022 (95 % CI) | P-Value |
|---|---|---|---|---|---|---|---|
| Elbow/Forearm | 1.69 | 1.73 | 1.93 | 1.14 (0.88, 1.48) | 0.32 | 1.12 (0.86, 1.45) | 0.39 |
| Shoulder | 1.63 | 1.38 | 1.20 | 0.74 (0.55, 0.99) | 0.04 | 0.87 (0.64, 1.19) | 0.39 |
| Groin/Quad | 0.38 | 0.25 | 0.11 | 0.29 (0.13, 0.68) | <0.001 | 0.44 (0.18, 1.06) | 0.06 |
| Hamstring | 0.38 | 0.19 | 0.30 | 0.79 (0.43, 1.45) | 0.45 | 1.58 (0.77, 3.26) | 0.21 |
| Knee | 0.30 | 0.27 | 0.24 | 0.79 (0.4, 1.55) | 0.49 | 0.88 (0.44, 1.77) | 0.73 |
| Foot/Ankle | 0.28 | 0.25 | 0.21 | 0.72 (0.35, 1.47) | 0.37 | 0.81 (0.39, 1.69) | 0.58 |
| Torso | 1.19 | 1.41 | 1.01 | 0.85 (0.61, 1.19) | 0.35 | 0.72 (0.52, 0.99) | 0.04 |
| Head/Neck | 0.21 | 0.21 | 0.19 | 0.92 (0.42, 2.02) | 0.84 | 0.92 (0.42, 2.02) | 0.84 |
| Calf/Lower Leg/Shin | 0.17 | 0.19 | 0.21 | 1.18 (0.53, 2.64) | 0.68 | 1.08 (0.49, 2.37) | 0.84 |
| Biceps/Triceps | 0.28 | 0.25 | 0.33 | 1.17 (0.62, 2.19) | 0.63 | 1.31 (0.68, 2.52) | 0.41 |
| Hand/Wrist | 0.65 | 0.33 | 0.21 | 0.32 (0.17, 0.59) | <0.001 | 0.62 (0.31, 1.24) | 0.17 |
| Hip/Glute | 0.13 | 0.22 | 0.21 | 1.63 (0.67, 3.92) | 0.28 | 0.93 (0.44, 1.98) | 0.85 |
3.4. Elbow-specific injuries
Elbow-specific injury comparison of the 2023 season against the 2021 and 2022 seasons showed no statistically significant difference (P > 0.05) for Tommy John Surgery, Flexor Tendon Injuries, or Other Elbow Injuries (ie; inflammation). See Table 4.
Table 4.
Elbow-specific injury analysis of the 2021 and 2022 seasons versus the 2023 MLB pitch clock season (IRR, Incidence rate ratio; IR, Incidence Rate).
| Injuries | 2021 IR | 2022 IR | 2023 IR | IRR 2023 vs. 2021 (95 % CI) | P-Value | IRR 2023 vs. 2022 (95 % CI) | P-Value |
|---|---|---|---|---|---|---|---|
| Tommy John | 0.32 | 0.47 | 0.43 | 1.35 (0.76, 2.41) | 0.31 | 0.9 (0.54, 1.51) | 0.69 |
| Flexor Tendon Injury | 0.59 | 0.52 | 0.57 | 0.97 (0.61, 1.54) | 0.90 | 1.09 (0.68, 1.75) | 0.72 |
| Other Elbow (I.e.; Inflammation) | 0.79 | 0.73 | 0.93 | 1.18 (0.81, 1.72) | 0.39 | 1.28 (0.87, 1.89) | 0.20 |
4. Discussion
This study demonstrated that after one year of the MLB pitch clock, there was a statistically significant decrease in the total number of injuries, shoulder injuries, groin and quad injuries, and hand and wrist injuries when compared with the 2021 MLB season. The 2023 MLB injury rates showed a statistically significant decrease in the total number of injuries, undisclosed injuries, and torso injuries compared to the 2022 MLB season. The remaining categories showed no statistical difference in injuries when comparing the 2023 to the 2021 or 2022 seasons. There was no statistical difference in the injury rates of elbow injuries. Longitudinal tracking of injuries in the pitch clock era is critical to see if the pitch clock will eventually affect injuries in pitchers.
From these results, the MLB pitch clock did not lead to a rise arm or overall injuries. There may be multiple factors that are currently leading to arm injuries. A recent spike in injuries came with the COVID-19 affected 2020 season, due to interruptions in training and playing schedules.18,19 Longitudinal effects could be lingering from the COVID-19 disruptions. In addition, other factors and theories need further exploration to find the primary culprit of injuries in pitchers. These factors include things such as velocity and spin rate force on the elbow,2,8,9 pitcher grip ability without sticky substance,12 pitch usages,9 pitch load over youth and amateur careers,10,11 training strategies23 and effects of pitching mechanics.7 A real possibility is that this problem is due to a multifactorial combination of these theories. However, none of these factors have been identified as the primary culprit, and must be analyzed to rule out a single culprit.
Future longitudinal analysis regarding the effect of the MLB pitch clock is critical to address the factors leading to the arm injury crisis in Major League Baseball. Additionally, further studies should also examine additional theories across professional and amateur levels. These studies provide useful insight, and will help guide the development of throwing programs, rule changes, practitioner management of patients, and rehabilitation protocols.
This study was not without limitations. The first limitation is the study only evaluated the regular season to create a consistent comparison. Injuries during spring training, the post-season, and the off-season were excluded. The addition of these periods would make a comparison of the seasons impossible, due to other unique confounding factors outside of the season. The second limitation is the comparison used the 2021 season, which experienced an injury spike due to COVID-19 interruptions in the 2020 season.19 This season could potentially confound the effect of the pitch clock due to lingering effects. The third limitation is that the study only goes back to 2021 due to the previously mentioned aberrations in the 2020 season.18,19 Exclusion of 2020 was important to remove a potential confounder. In order to compare if the pitch clock had a sudden effect, comparison to the two most recent seasons before the pitch clock was ideal.
5. Conclusion
The total number of injuries decreased significantly after implementation of the MLB pitch clock in 2023. Although the 2023 season had the highest total number of elbow and forearm injuries, the rate of elbow injuries in pitchers did not significantly change when compared with each of the 2021 and 2022 MLB seasons. Further studies that track across multiple seasons in the future will be needed to determine if the pitch clock has a longitudinal effect on elbow injuries in pitchers.
Guardian/patient's consent
This work is not human subjects research.
Funding statement
No funding was provided from any source for the development, conducting, or publication of this work.
Ethical statement
This study did not require institutional review board approval as all data is publicly available and does not qualify as human subjects research per United States Department of Health and Human Services policy 45 CFR 46.102.f
Credit author statement
TBP and NS conceived the study idea. TBP, NS, and MWB were involved in data collection and data analysis. TBP, NS, MWB and JR were involved in data interpretation, manuscript development, manuscript writing, manuscript formatting, and manuscript editing. JR and TBP provided administrative support and guidance.
Ethical approval
This study did not require institutional review board approval as all data is publicly available and does not qualify as human subjects research per United States Department of Health and Human Services policy 45 CFR 46.102.f.
Declaration of competing interest
The authors of this research declare no conflicts of interest.
Acknowledgements
We acknowledge the University of Nebraska Medical Center College of Public Health and Elijah Theye, MPH for assistance with statistical analysis.
References
- 1.Players' union head blames quicker pitch clock after series of pitcher elbow injuries. (2024). Accessed: May 18, 2024: https://apnews.com/article/pitch-clock-injuries-union-a12908df1de88e04190b6f42db8a1673].
- 2.LaPrade C.M., Cinque M.E., Safran M.R., Freehill M.T., Wulf C.A., LaPrade R.F. Using advanced data to analyze the impact of injury on performance of major league baseball pitchers: a narrative review. Orthop J Sports Med. 2022;10(7) doi: 10.1177/23259671221111169. Published 2022 Jul 20. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Camp C.L., Dines J.S., van der List J.P., et al. Summative report on time out of play for major and minor league baseball: an analysis of 49,955 injuries from 2011 through 2016. Am J Sports Med. 2018;46(7):1727–1732. doi: 10.1177/0363546518765158. [DOI] [PubMed] [Google Scholar]
- 4.Griffith T.B., Conte S., Poulis G.C., Diamond A., D'Angelo J., Camp C.L. Correlation of rehabilitation and throwing program milestones with outcomes after ulnar collateral ligament reconstruction: an analysis of 717 professional baseball pitchers. Am J Sports Med. 2022;50(7):1990–1996. doi: 10.1177/03635465221093995. [DOI] [PubMed] [Google Scholar]
- 5.Liu J.N., Garcia G.H., Conte S., ElAttrache N., Altchek D.W., Dines J.S. Outcomes in revision Tommy John surgery in major league baseball pitchers. J Shoulder Elbow Surg. 2016;25(1):90–97. doi: 10.1016/j.jse.2015.08.040. [DOI] [PubMed] [Google Scholar]
- 6.Erickson B.J., Ahn J., Chalmers P.N., et al. Reasons for retirement following ulnar collateral ligament reconstruction among major league baseball pitchers. Orthop J Sports Med. 2017;5(12) doi: 10.1177/2325967117745021. Published 2017 Dec 21. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 7.Anz A.W., Bushnell B.D., Griffin L.P., Noonan T.J., Torry M.R., Hawkins R.J. Correlation of torque and elbow injury in professional baseball pitchers. Am J Sports Med. 2010;38(7):1368–1374. doi: 10.1177/0363546510363402. [DOI] [PubMed] [Google Scholar]
- 8.Bushnell B.D., Anz A.W., Noonan T.J., Torry M.R., Hawkins R.J. Association of maximum pitch velocity and elbow injury in professional baseball pitchers. Am J Sports Med. 2010;38(4):728–732. doi: 10.1177/0363546509350067. [DOI] [PubMed] [Google Scholar]
- 9.Prominent MLB team physician sounds alarm on pitching injuries. (2024). Accessed: May 18, 2024: https://www.nytimes.com/athletic/5325032/2024/03/08/elbow-injuries-mlb-pitchers/.
- 10.Vance D.D., Alexander F.J., Kunkle B.W., Littlefield M., Ahmad C.S. Professional and amateur pitchers' perspective on the ulnar collateral ligament injury risk. Orthop J Sports Med. 2019;7(6) doi: 10.1177/2325967119850777. Published 2019 Jun 20. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.Parks E.D., Ray T.R. Prevention of overuse injuries in young baseball pitchers. Sport Health. 2009;1(6):514–517. doi: 10.1177/1941738109343543. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 12.Rays' Tyler Glasnow points to substance rule for injury: ‘That's why I got hurt’. 2021. https://www.nytimes.com/athletic/4209598/2021/06/15/rays-tyler-glasnow-points-to-substance-rule-for-injury-thats-why-i-got-hurt/
- 13.Pitch Timer (2023 rule change) 2022. https://www.mlb.com/glossary/rules/pitch-timer
- 14.Sonne M.W., Keir P.J. Major League Baseball pace-of-play rules and their influence on predicted muscle fatigue during simulated baseball games. J Sports Sci. 2016;34(21):2054–2062. doi: 10.1080/02640414.2016.1150600. [DOI] [PubMed] [Google Scholar]
- 15.Gillett J.S., Dawes J.J., Spaniol F.J., et al. A description and comparison of cardiorespiratory fitness measures in relation to pitching performance among professional baseball pitchers. Sports. 2016;4(1):14. doi: 10.3390/sports4010014. Published 2016 Feb 25. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.Gottlieb R., Shalom A., Calleja-Gonzalez J. Physiology of basketball - field tests. Review article. J Hum Kinet. 2021;77:159–167. doi: 10.2478/hukin-2021-0018. Published 2021 Jan 30. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 17.Injury report. Fangraphs. 2024 https://www.fangraphs.com/roster-resource/injury-report [Google Scholar]
- 18.Platt B.N., Uhl T.L., Sciascia A.D., Zacharias A.J., Lemaster N.G., Stone A.V. Injury rates in major league baseball during the 2020 COVID-19 season. Orthop J Sports Med. 2021;9(3) doi: 10.1177/2325967121999646. Published 2021 Mar 16. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 19.Platt B.N., Sullivan B.M., Dripchak S., et al. A plague of their own: injury incidence remains elevated in the 2021 major league baseball season compared to pre-COVID-19 seasons. Int J Sports Phys Ther. 2022;17(6):1104–1112. doi: 10.26603/001c.38479. Published 2022 Oct 1. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 20.Fuller C.W., Ekstrand J., Junge A., et al. Consensus statement on injury definitions and data collection procedures in studies of football (soccer) injuries. Br J Sports Med. 2006;40(3):193–201. doi: 10.1136/bjsm.2005.025270. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 21.Lemaster N.G., Stone A.V. Injury rates in major league baseball during the 2020 COVID-19 season. Orthop J Sports Med. 2021;9(3) doi: 10.1177/2325967121999646. Published 2021 Mar 16. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 22.2021. https://www.mlb.com/glossary/transactions/26-man-roster
- 23.Melugin H.P., Leafblad N.D., Camp C.L., Conte S. Injury prevention in baseball: from youth to the pros. Curr Rev Musculoskelet Med. 2018;11(1):26–34. doi: 10.1007/s12178-018-9456-5. [DOI] [PMC free article] [PubMed] [Google Scholar]