Job, Trey DWCross, Matthew RCronin, John B2025-09-222025-09-222025-06-11International Journal of Sports Physiology and Performance, ISSN: 1555-0265 (Print); 1555-0273 (Online), Human Kinetics, 1-7. doi: 10.1123/ijspp.2024-05301555-02651555-0273http://hdl.handle.net/10292/19834Purpose: The objective of this study was to explore the effects of training using wearable resistance (WR) applied above the elbow of the throwing arm on throwing velocity, arm speed, shoulder internal and external rotation, strength, and range of motion in baseball pitchers. Methods: College baseball pitchers (N = 17) participated in a volume-matched 6-week throwing program, twice per week, unloaded (quasi-control) or with WR added to the upper arm (intervention). Arm speed was measured with an inertial sensor, throwing velocity via radar gun, shoulder rotator peak force (Fₘₐₓ) with a strain gauge, and range of motion by a goniometer, before and after training. Linear mixed-effects models were used to examine differences between groups, time (pre and post), and their interaction with random intercepts for participants. Results: A significant effect from pretesting to posttesting was observed in external-rotation range of motion (η²ₚ =.456, P = .005) and tended to increase more in the control group (interaction, η²ₚ =.261, P = .047). Otherwise, no other statistically significant differences were observed. Conclusion: This was the first WR training study with pitchers, and the lack of clear improvement using upper-arm WR loading was notable. Future researchers should explore the efficacy of lower-arm loading and/or potentially increase training volume as a means of stimulating adaptation.This is the Author's Accepted Manuscript of an article published in the International Journal of Sports Physiology and Performance © 2025 Human Kinetics, available at DOI: 10.1123/ijspp.2024-05301106 Human Movement and Sports Sciences1116 Medical Physiology1701 PsychologySport Sciences3202 Clinical sciences3208 Medical physiology4207 Sports science and exerciseloaded throwingshoulder strengthpitchingresistance trainingthrowing velocityJournal ArticleOpenAccess10.1123/ijspp.2024-0530