In January 2017, the United States Marine Corps (USMC) introduced heightened pull-up requirements as part of revised standards for the Physical Fitness Test (PFT), with a goal of improving combat readiness. While these standards were intended to address the physical demands of contemporary military operations, they also raise concerns about potential adverse health impacts, particularly related to upper body musculoskeletal injuries (MSKIs), among active-duty male Marines. An open cohort study of all active-duty male Marines was used to assess the incidence of upper body MSKIs from fiscal years 2014 to 2023. Data was obtained from the Military Health System Data Repository (MDR) using relevant ICD-9 and ICD-10 codes for upper-extremity injuries. Single group interrupted time series (ITS) analyses were performed to evaluate trends in injury rates (per 10,000 male Marines) before and after the policy intervention, stratified by age, race/ethnicity, body mass index (BMI), and military rank. From 2014 to 2023, the overall upper-body MSKI rate among male Marines increased from 9.0% to 9.4%. Prior to the PFT policy change, injury rates exhibited a significant downward trend (ƅ1=-5.09, p <.0001), however, following the policy change, this trend reversed, showing a significant increase in upper-body injury rates (b3=5.11, p < .0001). A decrease in injury rates was observed immediately after the increased pull-up requirement, but this change was not statistically significant (b2=-4.00, p=0.4307). After accounting for baseline and immediate effects, significant trends in upper-body injury rates following the PFT policy change were also observed by age, BMI category, and rank. After the PFT policy change, significant increasing injury rates were noted in ages less than 20 years (b1+b3=0.88, p=0.0007) and decreasing rates in ages 40-49 (b1+b3=-1.21, p=.0461). Immediately following the PFT policy change, a large change in injury rates was observed in male Marines with obesity (b2=-17.01, p=0.0349), and the decreasing trend remained steady after accounting for baseline and immediate effects (b1+b3=-1.09, p=0.0059). The analysis by rank revealed significant increasing injury rates among senior enlisted only in the period after the policy change (p=.0123), but no significant immediate effect was observed (p=.5965). There were no significant findings of post-intervention injury rates from other categorical divisions assessed, including no racial or ethnic changes in rates. The 2017 increase in pull-up requirements was associated with a reversal of previously declining trends in upper body MSKIs among male Marines. These findings suggest that the policy change may have inadvertently contributed to increased upper-body MSKI in some groups of male Marines. Future policy modifications should strike a balance between fitness objectives and injury prevention strategies to optimize operational readiness and long-term musculoskeletal health in military personnel.