Physiological Effects Observed In Police Academy Cadets During Simulated Occupational Stress In A Hyperthermic Environment

Abstract

First responders (e.g., police) may be exposed to physical occupational stressors in the line of duty which may place them at risk for acute cardio-metabolic events (e.g., myocardial infarction). Environmental challenges may exacerbate this risk. PURPOSE: To observe the impact of a hyperthermic versus thermoneutral environment on physiological responses in police cadets performing a simulated occupational task. METHODS: Using an environmental chamber, 10 police cadets (22.2 ± 2.3 years), completed two occupational task exercise conditions in hyperthermic (HT, 380C) and thermoneutral (TN, 220C) environments on separate days. During each condition, participants completed a 10-minute treadmill walk at 70%-80% of their maximal heart rate followed by a 5-minute 50 lb sandbag lift. Participants had 10 seconds to lift the sandbag onto a table then another 10 seconds to place it back on the ground. The walk and lift were completed two times each per condition. Heart rate (HR), ratings of perceived exertion (RPE), and core temperature (T) were recorded immediately before entering the chamber (baseline), in the chamber at the conclusion of the occupational task (post-exercise), and outside the chamber after 10 min of rest (recovery). Two condition (HT, TN) by three time point (baseline, post-exercise, recovery) repeated measures ANOVAs were utilized to assess all dependent variables. Post-hoc analyses were performed using t-tests. RESULTS: Significant (F ≥ 8.6, p ≤ 0.003) condition by time interactions were observed for all dependent variables. There were no differences (t ≤ 2.0, p ≥ 0.07) across conditions in HR (76 ± 11 bpm TN, 82 ± 14 HT), RPE (6.4 ± 1 TN, 7.1 ± 2.4 HT), or T (37.2 ± 0.30C TN, 37.5 ± 0.20C HT) at baseline. However, each of these variables were significantly (t ≥ 2.3, p ≤ 0.05) greater post-exercise (104 ± 12 bpm TN, 146 ± 16 bpm HT; 8.9 ± 2.4 RPE TN, 13.4 ± 3.1 RPE HT; 37.6 ± 0.30C TN, 38.3 ± 0.30C HT) and during recovery (78 ± 12 bpm TN, 92 ± 13 HT; 6.7 ± 1.2 RPE TN, 7.7 ± 2.2 RPE HT; 37.4 ± 0.20C TN, 38.0 ± 0.30C HT) in the HT versus the TN condition. CONCLUSION: Concomitant occupational tasks and heat stressors increased physiologic and perceived measures of exertion and body temperature in police cadets beyond that of the occupational tasks alone.