PROJECT SUMMARY/ABSTRACT The fire service has one of the highest rates of occupational injuries incurring a large economic burden. Sudden cardiac death, and strains and sprains from slips, trips and falls and overexertion are frequently cited as the most common fatal and non-fatal injuries. Recent research has demonstrated that high-intensity interval training (HIIT) and multi-factorial neuromuscular training programs that include dynamic stretching, core stability, balance, and medicine ball exercises can specifically target the primary risk factors of these injuries, while improving firefighter performance. However, 75% of firefighters fail to achieve minimum physical activity recommendations, with those exercising on-duty experiencing surprisingly high rates of exercise-related injuries. In addition, with only 27% of fire departments implementing fitness programs, novel strategies are needed to improve implementation efforts of safe and evidence-based exercise that address key barriers to worksite exercise adherence. Preliminary work from our team has demonstrated that a ?train-the-trainer? (TRAINER) model, including professional supervision, can reduce the risk of injury in similar populations (i.e. military cadets). The objective of the current proposal is to determine the feasibility and obtain preliminary data on the initial changes and intervention fidelity to a TRAINER delivered integrated exercise routine (including a neuromuscular warm-up and HIIT) at fire stations. The main hypotheses are that firefighters will adhere to the TRAINER delivered integrated exercise program as intended and will exhibit clinically important improvements in primary risk factors for cardiovascular disease (CVD) and strain and sprain injuries. A two- arm cluster randomized feasibility and proof-of-concept study of a 6-week TRAINER intervention will be conducted with 40 career firefighters clustered by fire station. This study is innovative because 1) it includes an exercise strategy that facilitates on-duty exercise adherence and targets the primary fatal and non-fatal injuries in the fire service, and 2) explores a novel use of the TRAINER model to improve the implementation efforts of exercise programs at fire stations. In Aim 1, our multidisciplinary team will examine the feasibility of the TRAINER delivered integrated exercise program in firefighters. We will determine recruitment and retention rates, the willingness to be randomized, and the adherence to and acceptability of the 6-week intervention. In Aim 2, we will determine intervention fidelity and short-term changes in risk factors for CVD and strain and sprain injuries. The expected outputs and outcomes of this innovative project are critical to further Research to Practice (r2p) efforts in the fire service. Furthermore, a unique strength of this R03 includes the strong support from a leading tactical fitness organization with a national network of certified fitness professionals to enhance the dissemination of this project nationwide in a future large-scale trial. This proposal directly addresses 3 primary strategic goals (# 1,3, and 6) outlined in the Public Safety sector and cross-sector agenda items that include the reduction of CVD, musculoskeletal injuries, and fall-related injuries.