Setting pitching loads to reduce elbow stress in young pitchers: Focus on subjective effort and ball velocity

To determine the relationship between pitching intensity based on subjective effort and ball velocity and elbow valgus torque during pitching.

We recruited Thirty-three young baseball pitchers aged ten to fourteen years. The exclusion criteria included that injured, recovering from injury, or cannot currently pitch at full effort. The participants pitched at a distance of 16m or 18.44m at maximum, 75%, and 50% subjective effort, and then pitched at 75% and 50% maximum ball velocity. Pitchers performed 5 pitches for each pitching condition, and the order 75% and 50% conditions was random. Pitchers were outfitted with a wearable sensor sleeve that recorded the elbow valgus torque. Ball velocity was measured using a radar gun. We calculated estimates of the elbow valgus torque at 75% and 50% based on the elbow valgus torque at maximum subjective effort. The elbow valgus torque was compared between estimates and 2 pitching conditions in each 75% and 50% condition using a Dunnett test.

In the 75% pitching condition, there were no significant differences in the elbow valgus torque in either the subjective effort condition (26.5 ± 10.3 Nm) or ball velocity condition (22.1 ± 9.0 Nm) compared to the estimate (23.6 ± 8.4 Nm) (P = 0.342 and P = 0.948, respectively). In the 50% pitching condition, the elbow valgus torque was significantly greater in the subjective effort condition (23.0 ± 9.2 Nm) than in the estimate (15.7 ± 5.6 Nm) (p=0.001). However, no significant differences were found between the estimates and ball velocity condition (12.7 ± 5.6 Nm) (p=0.144).

At 50% pitching condition, pitching by the subjective effort was greater elbow torque than the estimated value, indicating that subjective effort throw overload the elbow. Therefore, the pitching intensity based on ball velocity is desirable to achieve a 50% load on the elbow joint during pitching. At 75% pitching condition, no significant differences were found either the subjective or ball velocity conditions compared to the estimates, both of which are nearly at the intended load.

In the early stages of resuming pitching, especially when setting a 50% loading level, it is important to base the pitching action on the velocity to avoid overloading the elbow.