Firefighters engage in physically demanding tasks, often in unstable environments. Optimal firefighter physical fitness is vital to ensuring their safe and efficient work performance and reducing the risk of health problems. Growing evidence suggests that cardiac events are the primary contributor to line-of-duty fatalities among firefighters [1,2,3], and firefighting as an occupation is associated with an elevated risk of injuries and certain cancers [4,5]. Cardiorespiratory fitness (CRF), a measure of the circulatory and respiratory systems’ ability to transport oxygen to the body’s cells during physical activity [6], is an important health indicator for firefighters as it is inversely associated with these adverse firefighter health conditions [7,8,9,10].

The US-based National Fire Protection Association (NFPA), a non-profit organization that develops firefighter health and safety standards through its Standard on Comprehensive Occupational Medical Program for Fire Departments (NFPA 1582), recommends that firefighters maintain a minimum CRF of 12 metabolic equivalents (METs), or 42 mL/kg/min of oxygen, aligning with CRF requirements for essential firefighting tasks including climbing, lifting, extricating, carrying, and dragging—all often performed while wearing heavy turnout gear [11]. This CRF benchmark has been used to characterize firefighter physical demands since the 1990s [12]. The NFPA advises fire departments to provide job-related fitness counseling for firefighters below the 12 METs CRF recommendation, prescribe an aerobic fitness program for those under 10 METs, and consider restricting essential firefighting tasks along with the fitness program prescription for those below 8 METs [13].

Volunteer firefighters comprise 65% of the US fire service [14]. However, large cross-sectional studies show that about 75% of US volunteer firefighters are unable to meet the NFPA CRF recommendation, compared to 61% of career firefighters [15,16]. Although volunteer firefighters tend to respond to fewer firefighting calls compared to career firefighters and generally serve in rural and low-population-density suburban communities (less than 25,000 people), volunteer firefighters have similar firefighting responsibilities as career firefighters [14]. Volunteer firefighters also generally spend less time in their fire stations due to their full-time jobs [17]. Their length of service, changes in ranks and duties, and competing responsibilities may contribute to their lower CRF.

The NFPA recommends fire departments provide periodic health screenings and physical examinations for firefighters, including physical fitness evaluations [13]. However, volunteer fire departments generally have limited resources to provide their members access to recommended routine occupational health monitoring and evaluations [14,17,18]. A US-based qualitative study of volunteer firefighters’ perspectives on factors influencing their physical fitness reported that work and family responsibilities and the unpredictability of calls deprioritized physical activity, while department fitness resources and advocates promoted physical activity [19].

Evidence suggests that volunteer fire departments face challenges in providing fitness-related support to their volunteers, despite departmental support being associated with improved fitness [18]. Research on the combined impact of fire department-level factors and individual firefighter characteristics on firefighter CRF is lacking, especially among volunteer firefighters, an understudied majority of the US fire service. There is a need for such studies to provide guidance on promoting and maintaining fitness among volunteer firefighters and their departments. Therefore, this study aims to investigate associations between volunteer firefighters’ CRF and individual factors (e.g., fire service experience), as well as their volunteer fire departments’ characteristics (e.g., fitness resources and training).

CAPS researchers enrolled 569 incumbent volunteer firefighters from 41 volunteer or combination departments. Thirty-seven fire departments (90.2%) provided fire department-level data that could be linked to 533 (93.7%) survey responses from CAPS-enrolled volunteer firefighters. Most participants (94.3%) were enrolled during or after 2021.

The participants were predominantly male (90.2%) and non-Hispanic white (92.1%), with an average age of 43.6 years (range: 18 to 82 years) and average fire service experience of 18.6 years (range: <1 to 60 years). Most were employed (83.3%) and 78.1% were employed full-time. Three-fourths of the participants had some college education or higher (74.9%). About one-third (35.1%) held some form of leadership rank at their fire department (Table 1).

This study is one of the first to examine volunteer firefighter and fire department characteristics in the context of CRF. Significant gaps were found in a recommended cardiovascular health indicator for these firefighters and as their department’s infrastructure for supporting CRF. Over 79% of the volunteer firefighters in this study did not meet the NFPA’s 12 METs recommendation for firefighter duty, suggesting that most volunteers in this study may have challenges performing firefighting tasks that are physically demanding. Just over a third of volunteer fire departments had a designated health, safety, and wellness person or committee, along with resources for fitness maintenance. Only half of the departments provided routine physical examinations to their members and recruits, which NFPA recommends occur annually.

If NFPA CRF recommendations for fire departments were applied, nearly a third of the CAPS-enrolled volunteer firefighters in this study should not perform essential firefighting tasks and 60% of participants would require aerobic fitness programs [13]. The degree to which participants in this study did not meet the 12 METs CRF recommendation was similar to that in other large US-based cross-sectional studies involving volunteer firefighters [15,16]. The CAPS volunteer firefighters also had a similar prevalence of overweight or obesity (81.9%) compared to a prior estimate for volunteer firefighters (78.4%) [16].

In the US, volunteer fire departments predominantly serve communities with under 25,000 people [14]. This study found that volunteer firefighters in departments serving larger communities had lower average CRF. While these departments tend to have more resources, they may also have more members, including older firefighters, which could contribute to lower average CRF. However, at the individual level, we observed a positive association between CRF and the number of calls responded to per month. This suggests that more active firefighters, regardless of department size, may have higher CRF, potentially due to greater physical demands or engagement in exercise to maintain readiness.

The 2020 US Fire Department Needs Assessment conducted by the NFPA found that 71% of surveyed volunteer or mostly volunteer departments lacked a basic firefighter fitness program, compared to 27% of career or mostly career departments. Similarly, 58% of volunteer departments did not provide medical or physical evaluations to their members, compared to 22% of career departments [18]. In comparison, our study found that a lower proportion (59.5%) of volunteer fire departments did not offer firefighter fitness resources or programs, suggesting a potential improvement. Additionally, the proportion of departments in our study that provided some form of routine physical examination (56.8%) was similar to the NFPA estimate (58%). Interestingly, despite the evidence supporting the benefits of these department programs, this study did not show any major associations between them and volunteer firefighter CRF [30]. In contrast, a US-based cross-sectional study compared career fire departments with fitness programs to those without these programs and observed that firefighters from departments with fitness programs had lower odds of being obese, five times greater odds of meeting the NFPA CRF benchmark, and generally had better fitness compared to those in departments without fitness programs [30]. A qualitative study of CAPS participants found that volunteer firefighting duties are challenging to balance with the work–life commitments and hinder participation in job-related physical fitness activities [19].

This study has some limitations. First, the small number of fire departments may hinder our ability to observe any true differences, especially in the multivariable analyses. Second, there may be selection bias due to the sampling approach, with fire departments having leadership and members potentially being more aware of health issues related to firefighting and more likely to enroll. This has the potential to increase reported physical activity levels and therefore increase the estimated CRF. In contrast, CAPS data collection occurred during and immediately after the COVID-19 pandemic, which may have reduced firefighters’ physical activity and increased their BMIs, thereby lowering their estimated CRF. The effect of the COVID-19 pandemic was not assessed in this study. Third, a CRF estimation model was used instead of direct measurement methods, as it is more cost-effective and practical for assessing large samples of volunteer firefighters. This model specifically relies on the PAR, which is used by CAPS and FFCCS researchers to assess firefighters’ physical activity levels. Although the CRF estimation model has been validated, it has lower precision for estimating CRF between 11 and 13 METs for firefighters [25] and uses a sex-related slope that may not fully generalize to females, so some caution is warranted when interpreting CRF among 40% of volunteer firefighters with CRF above 10 METs, and none of the female CAPS participants, who made up 9.8% (n = 52) of the CAPS sample, met the 12 METs recommendation. Fourth, while this study did assess whether fire departments had one or more health, safety, and wellness personnel or a committee, it did not assess this further (e.g., number of personnel or when committee/position was created), which impacted our ability to interpret the finding that CAPS departments with such person or committee were similar in terms of CRF measures to departments without them.

This study also has notable strengths. It includes geographic variation and representation from both rural and suburban departments. CRF was categorized using established recommendations from the NFPA (≤8, >8 to <10, and 10 to <12 METs), and volunteer firefighter estimated CRF was reported based on these levels, in addition to the recommendation for optimal firefighter CRF (≥12 METs). Furthermore, this study explores volunteer firefighter- and fire department-specific characteristics, identifying critical aspects of volunteer firefighters’ fitness improvement and maintenance.

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/fire8080319/s1, Table S1: Estimated cardiorespiratory fitness levels by demographic, fitness, and fire service characteristics of incumbent members of volunteer fire departments enrolled in CAPS (n = 533), 2019–2023. Table S2: Estimated cardiorespiratory fitness levels of CAPS-enrolled incumbent volunteer firefighters by fire department characteristics (n = 533), 2019–2023. Table S3: Associations between volunteer firefighter and fire department characteristics and firefighter estimated cardiorespiratory fitness as assessed by mixed effects multivariable linear and logistic regression models restricted to participants in non-leadership roles (n = 344).