Journal Club is a recurring series where we look at recent research in orthopedic sports medicine and talk through what it may mean for our patients.
This edition is a little different. Rather than one paper, we are looking at the whole body of published work on a single question, because that question has been argued loudly in public and the research behind it deserves a fair hearing.
The question:
Has the pitch clock caused the rise in elbow injuries in baseball?
The studies reviewed:
Puga TB, Scigliano N, Box M, Riehl J. The Major League Baseball pitch clock: first year analysis of pitcher injuries. Journal of Orthopaedics. 2024;57.
Puga TB, Box MW, Scambler W, Drawbert H, Riehl JT. Major League Baseball pitchers experienced increased flexor tendon and forearm injuries 2 years after pitch clock implementation. Arthroscopy, Sports Medicine, and Rehabilitation. 2025;7(4):101171.
Card RK, Liakos BJ, Schwartz JT, et al. Pitch clock increases tolerated workload before ulnar collateral ligament injury. Orthopaedic Journal of Sports Medicine. 2025;13(9).
Ashy CC, Baird HBG, Gannon S, Myer GD, Pullen WM, Slone HS. Older, starting, and pitchers with greater increase in pitch pace experience elevated injury risk following pitch clock implementation. Arthroscopy. 2026;42(5):868-876.
Mastroianni MA, Kumar P, Abdelaziz A, et al. The impact of the pitch clock on UCL surgery rates and performance in Major League Baseball pitchers.
Additional work examining pitch counts and injury incidence in response to the 2023 rule changes.
Level of evidence:
Level 3 and 4 throughout. These are retrospective cohort and case-control studies built on publicly available injury and pitch-tracking data. None of them is a randomized trial, and for a question like this one, none ever could be.
What changed, and why people worried:
Before 2023, the average time between pitches in Major League Baseball was about 22.6 seconds. The pitch clock cut that to 15 seconds with the bases empty and 20 seconds with runners on, later shortened to 18 seconds with runners on.
The concern was straightforward and physiologically reasonable. Pitching is a maximal effort powered by an energy system that needs time to recharge between efforts. Researchers had raised the possibility years earlier, when the clock was first tested in the minor leagues, that shortening the rest between pitches would leave the arm less recovered and place more stress on the ligaments and tendons that protect the elbow.
Then the 2024 season opened with a string of high-profile elbow injuries, the players association publicly blamed the clock, and the league pushed back. The argument has been going ever since, largely without reference to the studies that were being published alongside it.
What the studies found:
Overall injuries went down, not up.
The first-year analysis found that total pitcher injuries actually decreased in 2023 compared with both 2021 and 2022, with no statistical difference in the rate of Tommy John surgery, flexor tendon injuries, or other elbow injuries. The two-year follow-up found the same direction of travel, with 366 injuries in 2024 compared with 467 in 2021 and 461 in 2022.
UCL surgery rates did not change.
This is the most consistent finding across the group. One cohort study compared UCL tear incidence per 1000 innings pitched between the two seasons before the clock and the two seasons after, and found essentially no difference, 0.63 before and 0.67 after. The two-year injury analysis reached the same conclusion, reporting no associated increase in UCL operations two years after implementation. A case-control study of 52 pitchers who had UCL surgery and 104 matched controls found no difference between them in pitch timer duration or how often they worked quickly, and no difference in velocity, spin rates, release points, extension, or any of the modern pitch quality metrics.
But the workload picture shifted underneath.
Here is where it gets interesting. The same cohort study that found no change in injury rates found that pitchers were absorbing substantially more work before they got hurt. Pitchers who tore a UCL in the clock era had thrown 721 pitches that season before the injury, compared with 442 in the years before. They had logged 45.7 innings rather than 26.5. They threw more pitches per season and more per game, and they were younger when it happened.
Another analysis found that the time to a pitcher's first injury of the season lengthened, from roughly 143 days to 161 days, while the percentage of pitchers who got injured at all declined.
And the makeup of the injured group changed.
The case-control study found that the proportion of UCL surgeries happening to starting pitchers rather than relievers rose significantly after the clock arrived, from 30 percent to 55 percent, with a trend toward surgeries occurring earlier in the season. The two-year analysis found a significant rise in flexor tendon and forearm injuries in the pre versus post comparison, even as overall injuries fell.
The study that disagrees:
One recent paper reached a different conclusion, and it deserves to be taken seriously rather than set aside.
Instead of comparing league-wide injury counts between seasons, this group looked at individual pitchers and asked whether how much a given pitcher sped up predicted whether he got hurt. It found that each one second decrease in time between pitches was associated with 19 percent higher odds of injury overall, and 14 percent higher odds for throwing arm injuries specifically. Older pitchers were at higher risk, with each additional year of age adding 11 percent. Starting pitchers had roughly twice the odds of injury compared with relievers.
The two approaches are asking related but different questions. League-wide comparisons ask whether the rule made baseball as a whole more dangerous. This study asks whether, within the new rules, pitchers who work faster get hurt more often. Those can both be true. The clock may not have raised the overall injury rate while still meaning that an individual pitcher who rushes, particularly an older starter carrying a heavy load, is taking on risk he does not need to take.
Putting it together
A few honest conclusions from the whole set.
The evidence does not support the pitch clock as the cause of baseball's elbow problem.
Four separate groups, using different methods and different time windows, have failed to find an increase in UCL surgery attributable to the clock. That is a reasonably consistent answer to a narrow question.
The clock does appear to have changed how pitchers work.
Shorter games, more batters faced, more pitches absorbed before breaking down. Whether that reflects a protective effect, as one group suggested, or simply a healthier group of pitchers being asked to do more, is genuinely unsettled.
Pace probably still matters for the individual.
The dissenting study is the one that speaks most directly to a pitcher standing on a mound. Working faster than your own body wants to work is a modifiable thing, and there is now data suggesting it carries a cost.
We do not have strong evidence.
Every one of these studies is retrospective, built from public injury lists and tracking data rather than medical records, with all the misclassification that implies. Level 3 evidence tells you where to look. It does not close a question.
The elbow injury trend is older than the clock.
UCL injuries were climbing for two decades before 2023, alongside rising velocity, year-round play, and the chase for spin and stuff. The league has pointed out that the number of players arriving in professional baseball who have already had a UCL reconstruction rose from roughly six per year in the early 2010s to about twenty-four per year in the early 2020s. Those arms were hurt in high school and travel ball, long before any professional clock started running.
What this means for young pitchers and their families:
If you have been worried that a clock is what is hurting your son's elbow, the research points elsewhere. What it points toward is the same list we have been talking about for years. Throwing at maximum effort, throwing year-round without a real off-season, chasing velocity on a radar gun, pitching for multiple teams in the same season, and pitching while fatigued.
Those are the things that show up in the histories of the young throwers who end up in my office. They are also, unlike a rule in a professional league, entirely within a family's control.
The take-home
The pitch clock is the most visible change in baseball in a generation, which makes it a natural explanation for a problem that was already there. The published evidence does not support it as the cause of the UCL epidemic, though it does suggest that pitchers who speed up the most may carry more risk, and that the shape of who gets hurt has shifted toward starters earlier in the season.
The larger story has not changed. Elbows are failing because arms are being asked to throw harder, more often, and for more of the year than they were built to handle. That story starts long before anyone reaches a professional mound.
About the author
Joshua R. Eskew, MD is a fellowship-trained orthopedic sports medicine surgeon at Prisma Health's Steadman Hawkins Clinic of the Carolinas in Greenville, South Carolina, and an Associate Professor at the University of South Carolina School of Medicine Greenville. He completed his sports medicine fellowship at the Hospital for Special Surgery in New York, where he cared for athletes with the New York Mets. He serves as team physician for the Hub City Spartanburgers and Presbyterian College athletics, and his clinical and research focus includes UCL injuries and Tommy John surgery in throwing athletes.
This post is for general education and is not medical advice. If you or your athlete are dealing with elbow pain, please see a physician who can examine the arm and review any imaging.
