Why So Many Arm Injuries Happen Early in the Season

Arm injuries cluster at the start of the season. MLB's injury study found that more than 40% of injured-list placements for elbow injuries from 2010 to 2024 came in March or April, as reported by the Associated Press. One major league pitching coach quoted there put it down to pitchers not building up correctly.

If that happens to professionals with full medical staffs, it happens to high school pitchers who go from an indoor winter to a three-game week in March.

What goes wrong

The arm adapts to the work it is given. Trouble comes from a gap between what it has been prepared for and what it is suddenly asked to do. Common versions:

• Little or no throwing over the winter, then full-intensity bullpens in the first week of practice
• Plenty of flat-ground throwing but no time on a mound
• Short bullpens, then a 70-pitch outing in the first scrimmage
• Max-effort radar gun sessions before the arm is built up

How to build up

Give yourself six to eight weeks before the first game that matters.

• Start with volume at low intensity. Catch play at easy effort, building the number of throws and the distance first.
• Add intensity gradually. Move toward harder throws only after the arm handles the volume without lingering soreness.
• Get on the mound early enough. The slope changes the stress on the arm. Start with short, controlled bullpens and add pitches each week.
• Build pitch count in steps. If your first start might be 60 pitches, you should have thrown close to that in a bullpen or live session beforehand.
• Bring in off-speed pitches in order. Fastball command first, then changeup, then breaking balls.
• Keep lifting. Strength work continues through the ramp-up. It changes shape; it does not stop.

Signs you are going too fast

• Soreness that is still there two days later
• Pain in the elbow or the front of the shoulder, as opposed to general muscle fatigue
• Velocity or command dropping within a session earlier than usual

Any of these means hold the current level, or step back, before adding more. Pain that persists should be checked by a doctor or physical therapist.

The pitchers who are healthy in May are usually the ones who were patient in January.