CS #2: King-of-the-Mound Competition
It's easy to see how throwing mechanics can have a direct impact on ROM patterns. Many people view throwing mechanics and think it should be individualized based on how a specific individual learned to throw, or whether or not someone is having success within a certain pattern. But the fact of the matter is that there is a very objective approach when it comes to classifying some mechanical patterns as superior to others. Patterns that yield a similar velocity result with less wear-and-tear are more efficient, and therefore are superior to patterns that don't. We quantify this through a DVS Score, and in order to continue to validate it's effectiveness in doing so, we observe correlations between a DVS Score and injurious ROM patterns defined by research. The most recent of these observations is CS #2, which is outlined below.
CS #2: king-of-the-mound competition
A player's ROM patterns are widely considered to be one of the best ways to quantity injury risk in the throwing athlete. Furthermore, a pitcher’s mechanical pattern has been shown to play a role in the amount of stress transmitted to the shoulder and arm during throwing. However, much of the data available in this regard relates to the professional/adult population, with little insight into the effects on the youth population. Therefore, it’s the purpose of CS #2 to observe the correlation between ROM and a DVS Score (i.e. mechanical efficiency) within the youth population.
As the subjects in this study all have DVS Scores of at least 17 (Average 19), which is considered to reflect a relatively efficient mechanical pattern, their arms will undergo less stress during throwing, and therefore experience less injurious ROM patterns. This will be assessed by looking at the trends of Dominant Total Arc Motion Deficit (DTAMD), which is currently the research-gold-standard for quantifying throwing-related injury risk. More specifically, we expect that DTAMD will trend in a positive, less injurious direction relative to other accounts found within the literature (see Reinold et al in "Discussion" section).
- Setting: Controlled, High-Intensity Bullpen
- Number of Subjects: 16
- Average Age of Subjects: 15
- Average # of High-Intensity Throws: 45
- Average Ball Velocity: 70 mph
- Max Ball Velocity: 84 mph
- Average DVS Score: 19
16 asymptomatic male baseball pitchers with a minimum DVS Score of 17, and an average DVS Score of 19, participated in the study. Passive ROM measurements were recorded using a digital inclinometer for shoulder Total Arc Motion (TAM), Internal Rotation (IR), and External Rotation (ER) on both the throwing and non-throwing arms. For each shoulder, the limb was moved passively in each direction until maximal motion occurred. In order to ensure each shoulder achieved its full range of motion, the examiner used a combination of capsular end-feel and visualization of compensatory movement. The humeral head was not stabilized in order to allow for natural shoulder motion to occur. For each measurement of internal rotation and external rotation, the scapula was securely stabilized on the table. Measurements were taken at rest prior to throwing, and then post measurements were taken immediately after completion of throwing. As this was conducted with a competition setting, players that successfully advanced to the following stages inherently threw more pitches. However, maximum number of pitches per individual was not documented; rather, an overall "pitch-count average" of 45 pitches was calculated based on each thrower's demands.
Subjects in this study experienced a 0.5º increase in DTAMD relative to pre-throwing measurements.
Keep in mind here that the measurement were looking at (DTAMD) becomes injurious when it becomes less than -5. In other words, if the throwing arm becomes limited relative to the non-throwing arm by 5º or more, the chance of sustaining a throwing-related injury increases significantly. Therefore, patterns that trend in a positive direction (i.e. away from -5) relative to pre-throwing DTAMD measurements indicate that the body effectively handled the stress generated from throwing.
Taking a closer look at the table above, fix your eyes on the "DTAMD CHANGE" column. This number indicates the overall change, whether it be positive or negative, that each pitcher experienced in DTAMD from pre to post throwing. Although you see some individuals did indeed trend in a negative direction, which isn't desirable, the average "DTAMD CHANGE" for each pitcher was 0.5º. This indicates that on average, these players supported the demands of throwing relatively well.
In summary, we see that this same correlation between DVS Score and ROM risk factors holds true at the youth/adolescent levels as well, as DTAMD showed a slight positive increase from pre to post throwing. This is the exact opposite of what is to be expected after high-intensity throwing based on the evidence that exists. On that note, it's worth mentioning that even though the studies we use for comparison purposes used professional pitchers, which corresponds to higher ball velocities than the ones seen in CS #2, the perceived stress is relative based on their maturity, muscular development, and body weight.
In conclusion, the theme of what we’re showing is pretty straight forward. If you are throwing with a mechanical pattern that transmits less overall stress onto the throwing arm, you will be able to better handle the demands of throwing as shown in this study. Now, this doesn’t mean that just because you have good mechanics, you can throw as much as you want, or leave behind proper training and recovery techniques. However, mechanical efficiency provides you with a greater leash, which will allow you to throw more, throw more often, and extend you’re career. Elite level players that go through the system unscathed may do so for a variety reasons, a primary one being genetics, but they certainly aren’t doing themselves any favors as far as their mechanics go.