When college baseball players do certain shoulder exercises with bands, their serratus muscle (a key shoulder blade muscle) works harder if they move in a specific direction and add shaking motions — no matter how the band is set up.

When college baseball players do shoulder exercises with small back-and-forth movements, their shoulder and upper back muscles work harder than when they hold still or use light resistance—about 15% to 25% more.

Doing a specific shoulder exercise with a resistance band at a certain angle helps baseball players use the right shoulder muscles more and the wrong ones less, which might protect their arms from injury.

When college baseball players do shoulder exercises at a 90-degree angle, their rotator cuff muscle (infraspinatus) works harder if they move in a diagonal plane (scapular) instead of a side-to-side plane (frontal). The muscle shows nearly 70% of its max activity in the diagonal move, suggesting it’s a better way to strengthen that muscle.

When college baseball players do a specific shoulder exercise with two rubber bands instead of one, it makes a key rotator cuff muscle work harder — about 35% as hard as it can possibly work.