Shoulder Strength In Division I Baseball Pitchers Over the Course of the Season

Authors

Zachary T. Sylvester, Hackensack Meridian School of MedicineFollow
Richard J. Boergers, Seton Hall UniversityFollow

Abstract

The high rate of injuries in baseball pitchers has been linked to increased pitch velocity. Monitoring arm health through shoulder strength testing may link weakness with dysfunction or fatigue. PURPOSE: To measure shoulder strength at three points during the season (pre, mid, post) and identify shoulder muscle weakness. METHODS: Participants (N=14) were Division I baseball pitchers (age=20.36±2.13; weight=92.36±3.96 kg; height=188.32±4.66 cm). Participants were asked not to stretch or warm up prior to testing. Shoulder strength (flexion [FLX], internal rotation [IR], external rotation [ER], and scapular retraction [SR]) was assessed using an Activforce2 handheld dynamometer. For FLX, participants lay supine with the arm at their side, and the device was placed on the volar wrist. For IR, participants lay supine with the arm in 90/90, dynamometer on the volar wrist, and elbow stabilized. For ER, participants lay prone in 90/90, head facing the researcher, with the device on the dorsal wrist and posterior shoulder stabilized. For SR, participants lay prone with the arm in 90/90, head facing the researcher, with the dynamometer on the distal posterior humerus while the opposite posterior superior iliac spine (PSIS) was stabilized. Participants exerted force for three seconds for three total trials. Peak force was averaged and normalized to player’s weight [Strength (N)/Body Weight (kg)]. Repeated measures ANOVA with Holm’s post hoc analyzed pre-, mid-, and post-season strength differences. Effect size (ω²) is interpreted as small (≤0.01), medium (≥0.06), and large (≥0.14). RESULTS: FLX strength decreased significantly (p=0.008) between pre-mid and pre-post (p_holm=0.050 and p_holm=0.034, respectively) with a small effect size (ω²=0.048). SR strength was significant (p<0.002) and had a medium effect size (ω²=0.121). SR strength decreased significantly with a medium effect size (ω²=0.121) from pre-mid, pre-post, and mid-post (p_holm=0.049, p_holm=0.006, and p_holm=0.004, respectively). IR and ER strength did not significantly differ during the season. CONCLUSION: FLX and SR strength declined significantly across the season, but IR and ER showed no significant change. Monitoring shoulder strength throughout the season is valuable for assessing cumulative fatigue in pitchers.

Recommended Citation

Sylvester, Zachary T. and Boergers, Richard J. (2025) "Shoulder Strength In Division I Baseball Pitchers Over the Course of the Season," International Journal of Exercise Science: Conference Proceedings: Vol. 15: Iss. 7, Article 8.
Available at: https://digitalcommons.wku.edu/ijesab/vol15/iss7/8