CS #3: 1 game, 90 pitches, 21 DVS Score

cs #3: 1 game, 90 pitches, 21 dvs score

 

INTRODUCTION

As part of the ongoing series of looking at the relationship between DVS Score and injurious Range-of-Motion (ROM) patterns, I wanted to publish a brief study that we conducted last week. The study is outlined below, and unlike other Case Studies we've done in the past, this one was performed in a game setting. Although throwing a bullpen at 100% intensity is certainly stressful, it's not quite the same as throwing in a game. It's not uncommon for players to throw 2-3 miles per hour harder in a game than they would in a bullpen setting simply due to the extra adrenaline. Therefore, we were able to account for this difference as the subject threw in a a highly competitive, game atmosphere with playoff implications at stake.  

For those that aren't familiar, 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 adolescent population. Therefore, it’s the purpose of CS #3 to observe the correlation between ROM and a DVS Score (i.e. mechanical efficiency) as it relates to a high school pitcher . 

HYPOTHESIS

Based on the fact that the subject in this study has a DVS Score of 21, he will endure less relative stress during throwing, and therefore not exemplify any injurious ROM patterns associated with high intensity throwing. 

METHODS

Subject with a 21 DVS Score

  • Setting: Game
  • Location: Southern Durham High School
  • Number of Subjects: 1
  • Age of Subject: 17
  • Number of High-Intensity Throws: 90
  • Average Ball Velocity: 84 mph
  • Max Ball Velocity: 87
  • DVS Score: 21

One asymptomatic male baseball pitcher with a DVS Score of 21 participated in this 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 in a game setting, pitch-count could not be dictated. As such, the subject completed throwing at 90 total pitches. 

Results

Post throwing, the subject showed only a 1º decrease in DTAM (Dominant Total Arm Motion Deficit) compared to his pre-throwing measures. Additionally, the subject only lost 1º in DTAMD relative to his pre-throwing measures, and at no point does the subject exhibit any injurious ROM patterns relative to DTAMD, GIRD (Glenohumeral Internal Rotation Deficit), and GERD (Glenohumeral External Rotation Deficit).

BREAKDOWN

For those that aren't familiar, DTAMD (Dominant Total Arc Motion Deficit) is the throwing arm's relationship to the non-throwing arm. If the throwing arm has less total motion than its counterpart, we classify that as a negative number. If it has more, it's a positive number. When DTAMD becomes less than -5, it is considered injurious and the chance of sustaining a throwing injury significantly increases. Furthermore, it's important to understand that the body restricts motion when it becomes stressed and overused. Therefore, if an individual doesn't undergo a significant reduction in motion after throwing, regardless of the ROM pattern, it's safe to infer that they handled the stress from throwing relatively well. 

discussion

Once again, we can infer that this individual's mechanical efficiency played a large role in how he was able to handle the stress from high intensity throwing. To compare the results of this study with those of similar studies, you can refer to CS #1, under the "Discussion" section. Also, keep in mind that that this individual threw roughly 30-40 more pitches than the pitchers did in those comparison studies, which speaks even larger volumes about his mechanics. And yes, this individual may not be throwing as hard as most professionals, but the perceived stress is relative based on maturity, muscular development, and body weight.

Conclusion

Overall, if a pitcher with a lower relative DVS Score throws in a game, we would expect that pitcher to exhibit more injurious ROM patterns post throwing based on the associated stress. On the contrary, a pitcher that throws with greater mechanical efficiency and a higher DVS Score would be expected to undergo less stress, and therefore exhibit less injurious ROM patterns after throwing. CS #3 is a reflection of that. After throwing 90 pitches in a highly competitive game atmosphere, the culture would expect an individual to exhibit at least a few injurious-like symptoms. This is especially true towards the end of the season, as in the case with this particular pitcher, in which multiple starts, practices, and throws have accumulated throughout the year. However, with a DVS Score of 21, he likely manages stress relatively well compared to the average, and his ROM patterns are a reflection of that.

 

-Will