The parent project (“Fire Recruit Health Study”) for the present cross-sectional study started in early 2019 at two New England Fire Academies which train career firefighters. The aim of the “Fire Recruit Health Study” is to describe the food and fitness environment in New England fire training academies along with the baseline health/fitness of fire recruits, as well as the health changes which occur across the course of these 15 to 16 weeks training programs. In addition, the study seeks to look at subsequent health changes after joining a career fire department as a probationary firefighter. This effort will help identify opportunities and challenges to improve recruits’ health behaviors in future lifestyle intervention phases of the project.

The parent study was approved by the Institutional Review Board of Harvard T.H. Chan School of Public Health (IRB18–1902), and written informed consent was signed by all participants prior to their inclusion in the research.

During the first week of the academy, consented recruits completed an on-line, baseline questionnaire (Qualtrics platform) using their cell phone or a tablet, which included information on general and behavioral health, physical activity, sleep behaviors, cigarette smoking, and dietary information. Physical activity was assessed using a validated and standardized self-reported physical activity questionnaire.²⁴ Dietary data were collected via the English version of the PREDIMED questionnaire,²⁵ a validated 14-item questionnaire of Mediterranean diet adherence, which consists of 12 questions about food consumption and two questions about food intake habits. Height was measured to the nearest 0.6 cm (0.25 in.) in standing position with a stadiometer (seca). Body weight was measured to the nearest 0.11 kg (0.25 pound) with bare feet and underwear on a Bioelectrical Impedance Analysis scale (Tanita or InBody), which then automatically calculated body mass index (BMI) as the weight in kilograms divided by the square of height in meters and estimated body fat percentage.²⁶

Baseline adherence to Mediterranean lifestyle was assessed using the MEDI-Lifestyle score described in Table 1. The MEDI-Lifestyle score consists of seven dichotomously assessed items present in a Mediterranean healthy lifestyle (including: weight control [non-obese BMI], not smoking, Mediterranean diet, physical activity, limited tv-watching, adequate sleeping, and napping). A value of 0 or 1 was assigned to each of the seven Medi-Lifestyle components. Participants were assigned a value of 1 for each of the following: no smoking in the last 6 months, moderate-high physical activity (more than 16 METs-h/wk), high adherence to Mediterranean diet pattern (PREDIMED more than or equal to nine points),¹⁷ BMI less than or equal to 30 kg/m², time watching television (less than 2 h/d), adequate sleeping (between 7 and 8 h/d) and taking naps throughout the day (siesta or after lunch short nap); otherwise participants were assigned a value of 0. The total MEDI-Lifestyle score ranged therefore, from 0 to 7 (with 7 reflecting the highest adherence to a Mediterranean healthy lifestyle and 0 the lowest).

Hypertension (HTN): Blood pressure was assessed at baseline, 7 to 8 weeks, and 15 to 16 weeks. At each assessment, blood pressure was measured in a sitting position after at least 5 minutes resting in a seated position using an automated and calibrated sphygmomanometer (Omron, Kyoto, Japan) following the guidelines from the Report of the Working Group of the American College of Cardiology and American Heart Association on Clinical Practice Guidelines.²⁶ At each visit, an average of three readings (each taken at 1-minute intervals) was recorded. These averaged blood pressure readings were taken on more than or equal to two occasions and then averaged again over the more than or equal to two different visits to define each recruit’s blood pressure level as per the guidelines. Under the current criteria and for this study, the cut off for Stage 1 hypertension was an average systolic blood pressure more than or equal to 130 mm Hg or average diastolic blood pressure more than or equal to 80 mm Hg.²⁶

Aerobic capacity: Our team estimated the maximum oxygen absorption (VO₂ max) from each recruit’s timed 1.5 mile run during the baseline academy fitness assessment using the Jack Daniels formula.(VO₂ max=VO₂/percent max, where percent max=0.8+0.1894393×exp(−0.012778×time)+0.2989558×-+0.2989558×exp(−0.1932605×time)VO₂=−4.60—4.60+0.182258×velocity+0.000104×velocity² where time is the race time, and is race velocity in m/min)²⁷

The cut off for high versus low capacity was then established according to the median VO₂ max obtained for the recruit population.

The baseline questionnaire also included socio-demographic variables (eg, age, sex, educational level, marital status) as well as behavioral health information (The Beck depression inventory, the Patient health questionnaire, and the Posttraumatic Stress Disorder Checklist [PCL-5]).^10,28,29 The latter were used to collect trauma and depression symptoms. Academy training staff supervised and documented baseline push-up capacity (number performed in 1 min/single trial) and pull-up capacity (number in single trial).

Adherence to Mediterranean lifestyle was categorized based on the MEDI-Lifestyle score as low (0 to 2 pts.), medium (3 to 4 pts.), or high (5 to 7 pts.). The lowest category was used as the reference group for the analysis. Descriptive statistics were used to describe socio-demographic, anthropometric, mental health, and lifestyle characteristics of participants. Results are presented as stratified by the MEDI-Lifestyle adherence groups. To obtain descriptive statistics results, we used Pearson chi-squared tests for the binary and categorical variables, and one-way analysis of variance tests for the continuous variables.

The associations between the MEDI-Lifestyle and HTN and high aerobic capacity were assessed using logistic regression models. Odds ratios (OR) and 95% confidence intervals (CI) were calculated. Models were also created considering the index score as a continuous variable. To control for possible confounding factors, a multivariable model adjusted for age and sex was also calculated.

Secondary analyses were conducted to assess the individual contribution of each specific MEDI-Lifestyle component factor on the probability of prevalent HTN or high aerobic capacity at baseline. Logistic regression models were adjusted for the other components of the MEDI-Lifestyle score. The reference category was the absence of a healthy lifestyle (score 0 for each component factor). Additional analyses were performed by replacing total time watching television by total sitting time as the sedentary behavior component for calculating the MEDI-Lifestyle score.

All P values presented are two-tailed and a P < 0.05 was considered statistically significant. Statistical analyses were conducted using Stata SE12.0 (Stata Corporation, College Station, TX).