Firefighting is associated with an increased risk for cardiovascular events, which account for approximately 45% of line of duty deaths reported by the National Fire Protection Association. The increased cardiovascular risk during firefighting is likely related to increased cardiovascular work due to the physical demand, high heat burden, and poor environmental exposures. This study measures cardiovascular health and fitness annually in active firefighters. We believe this study will allow us to start filling an important gap in our knowledge about the change in firefighter cardiovascular health throughout their career. Observing the cardiovascular health and fitness of firefighters over time may allow us to identify predictors of adverse cardiovascular episodes or events and determine future avenues by which to help alleviate or alter these predictors to improve the health and safety of active firefighters.