Understanding Workload & Arm Health
A plain-language guide to the workload metric PitchSight tracks and how to keep a throwing arm healthy — written for athletes, parents, and coaches.
What is Acute:Chronic Workload Ratio (ACWR)?
Acute:Chronic Workload Ratio compares an athlete’s recent training load (the past 7 days) to their longer-term average load (the average of their last 4 weeks) to estimate whether they’re being pushed too hard, too fast. For throwers, workload can be measured in pitch counts and/or high-intent throws — and a spike in acute load relative to chronic load has been associated with increased injury risk, particularly at the shoulder and elbow.
The idea isn’t that any single high-effort outing is dangerous, but that the body needs time to adapt: a sudden jump from a “normal” week to a much heavier one can outpace the tissue’s ability to keep up. ACWR gives coaches, parents, and clinicians an early, objective signal — a “yellow flag” — to build in recovery before that mismatch turns into an injury.
While ACWR isn’t a perfect predictor, it’s one useful piece of a bigger monitoring picture — which is why PitchSight pairs workload data with a physical exam and imaging.
How to protect the player’s arm
- Follow pitch count rules. Every league sets limits on pitches per game — make sure they’re followed, including across multiple teams or private pitching coaches. All high-intent pitches add to the stress on the player’s arm, so coaches should communicate about workloads.
- Ensure proper rest. After pitching, the player needs rest days before throwing again. The number of rest days depends on how many pitches were thrown — see USA Baseball / Pitch Smart guidelines.
- Take time off. Young throwers should take at least 3 months off from high-intent throwing each year. Pitching year-round substantially increases injury risk.
- Don’t play through pain. Elbow pain during or after throwing — especially on the inside of the elbow — is a warning sign. Consider getting an evaluation with a sports-medicine PT or physician.
- Watch total volume. Playing on multiple teams increases total throwing volume and injury risk — make sure coaches and parents communicate.
- Play multiple sports. Cross-training builds overall athleticism and reduces the likelihood of overuse injury.
- Build overall fitness and mechanics. Strong legs, core, shoulders, and forearms help protect the arm. Proper mechanics — using the lower half of the body to create velocity — along with a regular arm-care (shoulder and forearm strengthening) program have been shown to reduce stress on the elbow in young pitchers.
- Use the Pitch Count Portal. Track pitch counts and your Acute:Chronic Workload Ratio (ACWR) — your 7-day workload compared to your previous 28-day average. Research shows that outside the 0.7–1.3 range, injury risk increases. Track velocity, tissue response, and more, and share with coaches across multiple teams, private pitching coaches, trainers, and healthcare providers.
This page is general educational information, not medical advice. For concerns about a specific athlete, consult a qualified sports-medicine professional.