WellSpan Health and the York Revolution partnered to publish a study on the effects of single-sport specialization in professional baseball.


Single-sport specialization has become a hot topic of conversation in recent years in youth athletics.

It’s led to studies on young athletes and the impact that it could have on their bodies.

Studies also have been conducted to determine if focusing on just one sport increases a young athlete's chances of making it to the professional level.

However, a study has never been done looking back on the careers of pro athletes to see if specializing in one sport led to serious injuries and if it helped the athletes reach the pro ranks.

During the 2016 Atlantic League baseball season, WellSpan Health and the York Revolution teamed up to change all of that.


In a study co-authored by John Deitch, Andrew Wilhelm and Changryol Choi, they anonymously surveyed 102 Atlantic League baseball players to see if they believed single-sport specialization helped them get to pro baseball and find out what percentage of those players have suffered a serious injury.

“In the survey, we asked questions about how early they specialized in a sport, which was baseball,” said Deitch, who is the director of sports medicine at WellSpan. “And whether or not they sustained an injury that kept them out of at least one year of competition in baseball at both the professional and youth level of baseball. We also asked if they felt it was important for them, as professional athletes now, that they specialized early.”

Study results:What the study found was that, of the 102 players surveyed, 50 of them (49 percent) specialized in baseball by the age of 9. Those who specialized experienced a significant injury in their careers at a higher rate than those who didn’t specialize. And 63.4 percent of players surveyed didn’t believe specializing in baseball helped them get to the pro level. The age range for the players surveyed was 22 to 40, with the median age being 29.

The players who completed the survey also believed that sport specialization was not necessary before high school and that young baseball athletes should not be encouraged to participate in a single sport because of an increased potential for suffering serious injury.

The report was published Sept. 22 in the Orthopaedic Journal of Sport Medicine.


WellSpan, Revs work together: This area of study has been of interest to Deitch going back more than a decade. The Revs and WellSpan have a strong working relationship, allowing Deitch and Wilhelm to go to them to work together on the study. To increase the validity of the findings, the survey was expanded to a larger group, leading to it including all of the Atlantic League.

WellSpan just concluded its sixth season working as the official team physician for the Revolution, while Choi just completed his fourth year as the team trainer.

Specialization and injuries: A major cause for an increase in injuries in single-sport specialized athletes is because they’re specializing in a skill set rather than building fundamentals of fitness, Deitch said.

Some common injuries found in one-sport specialized athletes are to their growth plates in their throwing arms, specifically in their elbows and shoulders, Deitch said.

Choi also said that more common injuries, such as ulnar collateral ligament (UCL) tears, which can require Tommy John surgery, and rotator-cuff surgeries are a result of single-sport specialization from a young age.

Plans to expand study: While the study only focused on baseball, Deitch does plan to continue and expand the research to other sports. He also plans to break down the data into more categories.

For instance, because American-born baseball players have more options to play other sports growing up, compared to Latino players, Deitch wants to see how the single-sport specialization numbers are broken down based on ethnicity.

Getting the word out: As for how the authors of this study plan to get the results out to younger athletes around the community, WellSpan works with several York-Adams League schools.

The hope is that the findings make their way to the right people to show them that it’s worth it for kids to play as many sports as possible growing up until, at the earliest, high school.

“The key message for parents, coaches and athletic administrators is that (what) health professionals in sports medicine have concluded, through research all across our country over the last few years, is that specializing early has a downside, and that downside is an increase in injury,” Deitch said. 

— Reach Patrick Strohecker at