6 Mechanical Faults That Can Increase a Pitcher's Risk for Injury

One of the best ways a pitcher can avoid injury, particularly of the shoulder and elbow, is by utilizing proper and repeatable throwing mechanics. The effect of faulty throwing mechanics on pitcher injury rates has been studied most extensively in high school and adolescent athletes, however, the concepts carry over to collegiate and professional pitchers as well. But what exactly does “proper throwing mechanics” entail?

First, it would be best to break down the action involved during a pitch. Each pitch consists of six distinct phases: 1. windup, 2. stride (sometimes referred to as early cocking), 3. late cocking 4. acceleration, 5. deceleration, and 6. follow through.

The windup phase includes any action that occurs from when the pitcher becomes set until they reach their balance point; the stride phase - as seen in the photo of Jose Berrios above - occurs from when the pitcher progresses from their balance point until the foot comes in contact with the ground; the late cocking phase occurs when the throwing arm achieves maximal external rotation (i.e. rotated “backwards”); the acceleration phase occurs once maximal rotation is achieved and lasts until the ball is released; the deceleration phase occurs after ball release; and the follow through phase occurs until the pitching motion is completed.

Faulty mechanics can arise during any of the six phases of pitching, however, they are least likely to appear during the windup and follow through. The American Sports Medicine Institute (ASMI) was the first entity to develop an assessment tool to evaluate and critique a pitcher’s mechanics, however, the tool was not able to predict injury risk.

The ASMI’s tool consists of 24 items, however, two studies - they can be found here and here - conducted separately were able to identify six items that increase a pitcher’s risk for injury if they are deemed to be faulty. These were: 1. supinated hand position when the elbow was maximally extended, 2. open or closed foot position at foot-ground contact, 3. backwards lean at foot-ground contact, 4. open shoulder positioning, 5. trunk to elbow angle below 90-degrees at foot-ground contact, and 6. excessive trunk lean at maximal shoulder external rotation. A study conducted by Emily Quatromoni - the inspiration of this article - found that these six items could be adequately identified upon visualization of a pitch.

Of these six, a supinated hand is the least likely to be seen amongst professional pitchers - again most of these studies are conducted with children or high school athletes as the test subjects with less instruction on proper mechanics. However, the other five can be seen time and again in professional pitchers. As an example: below is an image of new Twins’ starting pitcher Jhoulys Chacin with a slightly closed foot position.

Improper mechanics, such as the six highlighted above, increase the amount of stress placed through the shoulder and inner elbow, which in turn increases the risk for labral tearing and UCL sprain, among other injuries. These six mechanical faults can be avoided - or at least limited - with proper coaching, training, and minimizing pitcher fatigue, such as by establishing a firm maximum pitch count or innings limit. Below is again the image of Berrios displaying proper biomechanics (note: item six - minimal trunk lean at maximum shoulder external rotation - is not pictured as he has not reached that point in his throwing motion yet).

For a more dynamic visualization, I encourage you to watch the videos that Twins’ pitcher Lewis Thorpe posted to his Twitter feed the other day. Try to see if you can pick out the six phases of the pitch as well as the avoidance - or lack thereof? - of the six faulty mechanics.

https://twitter.com/ljthorpe33/status/1241026457918472198

MORE FROM TWINS DAILY

— Latest Twins coverage from our writers

— Recent Twins discussion in our forums

— Follow Twins Daily via Twitter, Facebook or email