In the past 15 years, Major League Baseball (MLB) players on the disabled list accounted for $7 billion in lost wages. And while multiple studies have researched possible causes of shoulder and elbow pain in the sport, injuries continue to occur.

Ideally, during preseason testing, players would find out about strength and motion deficits that might put them at risk for injuries so they could address them and avoid the injury altogether.

Turns out we might be nearing home plate on doing just that, thanks to a new study being conducted at the USC Division of Biokinesiology and Physical Therapy.

Professor of Clinical Physical Therapy Lori Michener, PhD, PT, and her research team recently received an MLB grant for their study, “Risk Factors Associated with Upper Extremity Injuries in Baseball,” which aims to explore these deficits during preseason training. The end goal is to be able to predict injuries before they happen, thereby avoiding them altogether.


Off to Spring Training

“We’re hoping to identify physical modifiable risk factors that are related to the development of shoulder and/or elbow pain,” said Michener, who will serve as the study’s principal investigator on the study. “By modifiable, I mean factors we can potentially address through a prevention program.”

Michener is working with Assistant Professor of Clinical Physical Therapy Jonathan Sum, DPT, and Associate Research Director Hillary Plummer, PhD, on this study.

With Plummer’s interest in researching biomechanics and injury analysis in baseball, Michener’s experience as a shoulder expert and Sum’s expertise with baseball, it seemed the perfect sport in which to conduct the trial. The four of them traveled to spring training in Phoenix, Arizona, on March 4 and 9 to conduct measurements on members of three minor league teams. Approximately 200 players took part, with all positions taken into account.


Running the numbers

While past studies have focused primarily on range of motion of the shoulder, this trial will approach the subject differently, looking at the correlation among muscle control; shoulder, trunk and leg strength; and subsequent injuries.

“We’re looking at strength and range of motion measurements of the shoulder, but we’re also incorporating somebody’s functional strength,” Sum said. “No studies to date have looked at the combination of measurements we’re doing — the legs, the core, the arms.”

Testing included shoulder range of motion using an inclinometer, a device that measures angles; shoulder strength via a dynamometer, which gauges power output; trunk and hip stability assessment through a step-down test off of a box that is then digitized and analyzed for degree of abnormal motion versus normal motion; and trunk/hip strength measured by having participants assume a side bridge position and hold it for as long as possible.

“We’re trying to figure out if somebody tests positive for one, two, three or five of these factors, are they the one who ends up getting an arm injury during the season,” Sum explained.


On the lookout for injuries

As the players hit the field and the season progresses, the rehab coordinator for the minor league system will report back to the trial team with details such as who was injured, what the injury was and when they were injured.

“We will compare the people who got injured to the people who didn’t and then develop prediction models to understand the relationship between the data we’ve collected and the injuries that developed,” Michener said. “The theory is we will find valuable information for the teams, which they can use to identify a player who may be at risk for injury and then intervene with a prevention program.”

Results of the trial will be submitted to national sports medicine conferences and for publication in peer-reviewed journals. The next step will be to use the findings to establish a tailored prevention program for each individual player, an advancement that could vastly affect MLB, according to Sum.

“If we can further shed light on risk factors for baseball players who have a higher chance of injury, this could mean less injuries, less time and dollars lost to injuries, a more competitive product on the field and higher earning potential for players.”

— Michelle McCarthy