Why Every Baseball Player Needs a Weekly Arm Assessment

Strength and length are critical ingredients to accelerating and decelerating the throwing arm.  Firstly, appropriate muscle length provides the range of motion to load the arm like a catapult, and secondly strength maintains the position of the arm in the shoulder socket from layback to ball release.

To ensure arm health and the highest level of performance, arm strength and range of motion need weekly assessment to provide early warning signs and valuable training insights.  But currently, only professionals and a handful of the top collegiate athletes get these evaluations, and it’s usually only at three times: 1) pre-season, (2) mid-season, and (3) end of the season.

In this article, we’ll talk about why and how increased testing is needed for throwing athletes at all levels.

Early Season Range of Motion Changes

A critical time point for assessment in pitchers is early in the season because it’s the most challenging as far as health. For example, opening months show the greatest surgical interventions for the elbow across all levels of play (2, 3). 

Early in the season, velocity is generally the lowest as players return from time off but gradually builds back as the season progresses.  Increased external rotation range of motion is a major change that adds pitch velocity is that external rotation of the shoulder improves.

The graph below has been adapted from previous research. You can see the range of motion increases early in the season, levels out around the midseason point, and maintains into the postseason (4) This increase in external rotation is known to help improve velocity (5).

Strength & Length Must Grow Together

Small changes in range of motion can provide benefit, but an increase in range of motion beyond 10 degrees without a simultaneous increase in strength can be problematic.

If strength is not increased to match the increase in length, loading on the shoulder and elbow can overwhelm the muscle, tendon, and ligament tolerance to strain. Pre-season throwing arm weakness is attributed to time off, but it’s made even worse from the cumulative fatigue that occurs with throwing as the season progresses.

Even after one bout of pitching, post-game shoulder flexion (raising the arm) and internal rotation (rotating the arm forward) strength drops for pitchers. An adapted graph from Mullaney et al. illustrates throwing arm weakness by over 15% because of repetitive pitching (6).

Strength Loss Creates Velocity Loss

In-game velocity decreases are as much as 5 mph in starting pitchers that are matched with strength declines (7). Velocity loss is protective to the athlete to match potential declines in tissue tolerance due to strength loss. Ball velocity loss can also offer elbow protection from the increased external rotation that occurs with decreased strength.

Despite the reduced risk to the throwing arm, throwing slower will not help pitchers experience success in baseball. Batters have more time to react, which improves their chances of barreling the ball.

Weekly Testing is the Perfect Guide

After reading these facts, you may ask yourself, what should I do to ensure sustained, high-level performance while mitigating risks?  We believe the best solution is to provide a continuous assessment to ensure that strength improves while keeping an eye on range of motion changes.

The ArmCare.com training platform provides a regular strength and range of motion assessment to customize a player’s program. Without correcting strength and range of motion imbalances a player’s likelihood of injury increases along with reduced performance.

ArmCare essentially takes the guesswork out of the training equation and adjusts training and workloads to match the demands of the season.

KEY CONCEPTS

• Velocity, range of motion, and strength fluctuate game to game all season long.
• Rapid increases in range of motion create risks if not matched with strength gains.
• Strength decreases following heavy workloads.  This results in a decrease in velocity and an increased injury risk to the elbow and shoulder. 
• Regular assessment and personalized training are paramount to monitor a player over the course of the season.

References

1. Burkhart SS, Morgan CD, Kibler W Ben. The disabled throwing shoulder: spectrum of pathology Part I: pathoanatomy and biomechanics. Arthrosc J Arthrosc Relat Surg. 2003;19(4):404-420.
2. Erickson BJ, Nwachukwu BU, Rosas S, et al. Trends in medial ulnar collateral ligament reconstruction in the United States: a retrospective review of a large private-payer database from 2007 to 2011. Am J Sports Med. 2015;43(7):1770-1774.
3. Camp CL, Conte S, D’Angelo J, Fealy SA. Epidemiology of ulnar collateral ligament reconstruction in Major and Minor League Baseball pitchers: comprehensive report of 1429 cases. J Shoulder Elb Surg. 2018;27(5):871-878.
4. Chan JM, Zajac J, Erickson BJ, et al. Upper Extremity and Hip Range of Motion Changes Throughout a Season in Professional Baseball Players. Am J Sports Med. 2020;48(2):481-487.
5. Crotin R, Bhan S, Karakolis T, Ramsey D. Fastball velocity trends in short-season minor league baseball. J Strength Cond Res. 2013;27(8):2206-2212. doi:10.1519/JSC.0b013e31827e1509
6. Mullaney MJ, McHugh MP, Donofrio TM, Nicholas SJ. Upper and lower extremity muscle fatigue after a baseball pitching performance. Am J Sports Med. 2005;33(1):108-113.
7. Murray TA, Cook TD, Werner SL, Schlegel TF, Hawkins RJ. The effects of extended play on professional baseball pitchers. Am J Sports Med. 2001;29(2):137-142.