PROJECT SUMMARY Cardiovascular disease is the leading cause of on-duty deaths among firefighters. Firefighters incur acute health risks including injury, fatigue, heat stress, and cardiovascular strain while protecting our communities. Appropriate physical fitness is an essential part of reducing these risks. Poor physical fitness, including low cardiorespiratory fitness and high body mass index, can contribute to increased risks of adverse cardiovascular, respiratory, and cancer (colorectal, prostate) outcomes, all major concerns among firefighters. The United States has 1.1 million firefighters, 67% of whom are volunteer firefighters. However, most firefighter heath research is conducted among career (paid) firefighters. While volunteer firefighters train for, and perform the same tasks as career firefighters, they differ in key ways that may lead to lower physical fitness maintenance. Volunteer firefighters are always on call for emergency responses, do not spend extended time in the fire station, and are expected to maintain training while balancing their primary employment and family life, reducing opportunity for fire-department promoted health programs. In this proposal, we investigate the predictors and barriers of physical fitness among volunteer firefighters, which are critical for developing health promotion programs targeted at this understudied majority. The proposed mixed-methods project will be conducted within the research infrastructure of the New Jersey Firefighter Cancer Assessment and Prevention Study, and will use previously collected survey data on firefighting and behavioral factors, and focus group data on individual- and fire-department level factors affecting physical fitness among volunteer firefighters. Volunteer firefighters will be compared to career firefighters from the national Fire Fighter Cancer Cohort Study. The proposed project has three specific aims: (1) To identify factors associated with physical fitness among firefighters and assess differences among volunteer and career firefighters; (2) To qualitatively explore potential individual- and fire-department level influences on physical fitness among volunteer firefighters; and, (3) To employ a mixed-methods analysis by triangulating quantitative and qualitative data regarding factors associated with physical fitness among volunteer firefighters. Multivariable regression analysis will be used to assess effects of behavioral factors and firefighter service exposures on physical fitness among volunteer firefighters compared with those for career firefighters. Thematic analysis will be used to generate an in-depth understanding of the barriers and promoters of physical fitness among volunteer firefighters. A convergent mixed-methods analysis will integrate quantitative and qualitative findings to explore how and why health behaviors and volunteer firefighting characteristics influence physical fitness. By investigating the predictors and barriers of physical fit...