As the 2019 baseball season is quickly approaching, I want to discuss why we see such high injuries early in the season with baseball players.
A study conducted by Posner er. al (2011) : Epidemiology of Major League Baseball injuries shows that injury rates are 10 times higher in April compared to September in major league baseball players. Additionally, injury rates have significantly gone up from 2002 to 2008. This study however didn't look at what happened in February and March...
Every year we hear about this injury epidemic plaguing baseball spring training; more specifically a high number of Tommy John surgeries, and Lat. strains, and it raises the question.. WHY?
To understand the spring injury epidemic for baseball athletes we need to understand the specific demands, and adaptation throwers see during the first few weeks back to throwing. As baseball athletes begin throwing they gradually acquire external rotation, more specifically the average thrower will gain about 5 degrees external rotation over the course of a season.
We have to appreciate and be cognizant that throwers who acquire a quick increase in external rotation means they are laying their arm back into positions where they don't actually have good stability; and when athletes crank back aggressively into positions that they aren't stable in, they put their elbow in a very vulnerable position.
Likewise, we look at the Latissimus Dorsi (Lat.) in that externally rotated position, the lat. is excessively lengthened in that externally rotated position to create anterior stability and prevent excessive external rotation, it's a pre-stretch prior to acceleration of the humerus. Therefore, this mechanism puts your anterior capsule, and your bicep tendon in a very vulnerable position. In summary, this excessive laid-back arm position can give a lot of people problems if they are not prepared for it.
What we tend to see are external rotation increases right when guys start to play catch; additionally, there is increasing evidence suggesting that weighted ball throwing can help assist external rotation, more than just throwing a regular five-ounce ball. Lastly, mound throwing, which requires significantly more separation and stress tends to significantly increase external rotation position.
Therefore, when spring throwing ramps up and athlete's jump back into bullpen and live at bats, sometimes that overload (stress) might be too much too quick for an athlete who is lacking stability in that laid back, externally rotated position.
The solution to this is to make sure your throwing programs are not too aggressive or excessive early on; spend a few weeks working on ground play and gradually build up. Concurrently, make sure you are working on a good strength and conditioning program and arm care program to develop good end range control. Lastly, above all don't wait too long to start your throwing program.