Preliminary Physiological And Psychological Characterization Of Career Firefighters Undergoing Smoke Diver Training

Smoke Diver training is an advanced, physically and mentally challenging course focusing on fire suppression and structure fire rescue skills for career firefighters (FF). Little is known about FFs pursuing this certification and how individual descriptors may influence physiological responses to training. PURPOSE: To characterize the general health of FFs undergoing a 5-day Smoke Diver course and to explore associations between health variables and stress biomarkers at rest and following a day of live drills. METHODS: Male FFs (N = 24; M ± SD; age, 31 ± 6 y; body mass index [BMI], 29.2 ± 4.2 kg·m-2) completed a survey to assess demographics, health behaviors (e.g., habitual sleep via Pittsburgh Sleep Quality Index [PSQI], physical activity [PA]), and posttraumatic stress disorder (PTSD) symptom severity (e.g., PTSD Checklist for DSM-5 [PCL-5]). In a subset of FFs (n = 8; age, 33 ± 4 y; BMI, 28.1 ± 3.7 kg·m-2), exploratory correlational analyses investigated associations between descriptives and stress biomarkers (white blood cells [WBC], red blood cells [RBC], hemoglobin [HGB], hematocrit [HCT]) at rest and in response to a full day of live drills (Δ, post-pre). RESULTS: FFs had 9 ± 5 y of service, 89.5% met federal PA guidelines (≥150 min·wk-1 of aerobic exercise and ≥ 2 days·wk-1 of resistance exercise), slept 6.8 ± 0.4 h per night, 74.1% slept poorly (PSQI Global Score = 5.7 ± 2.4; ≥ 5 indicates poor sleep quality), and reported low PTSD symptom severity (PCL-5 score = 5.6 ± 6.6). In our subset (n = 8), higher PSQI Global Scores were associated with high WBCs at rest (r = 0.71, p = 0.05) and changes in stress biomarkers following the live drills: ΔRBC (r = -0.81, p = 0.01), ΔHGB (r = -0.76, p = 0.03), and ΔHCT (r = -0.78, p = 0.02). Higher PTSD symptom severity was also associated with high WBCs at rest (r = 0.83, p = 0.01) and physiological stress post-drills (ΔRBC, ΔHGB and ΔHCT: r = -0.82 to -0.88, p ≤ 0.01 for all). CONCLUSIONS: FFs were, on average, middle-aged, overweight men, who met federal PA guidelines, experienced mild sleep dysfunction, and had low PTSD symptom severity. While a larger and more diverse sample is needed to enhance the generalizability of our results, we found that poorer sleep quality and higher PTSD symptom severity influences physiological stress in Smoke Diver trainees at rest and during live drills.