Stress hormones and vascular function in firefighters during concurrent challenges.

The purpose of this study was to examine the effects of concurrent physical and mental challenge on stress hormones and indicators of vascular function in firefighters. Twelve professional firefighters exercised at 60% VO(2max) while participating in a computerized Fire Strategies and Tactics Drill (FSTD-fire strategies condition [FSC]), and again at the same intensity without the mental challenge (EAC). No differences in the amount of work performed between conditions existed, although the FSC resulted in greater perceptions of overall workload. Epinephrine and norepinephrine demonstrated significant interaction effects with elevated levels during the FSC. Cortisol responses were significantly elevated across time and for the FSC. Positive correlations were found between cortisol and interleukin-6, endothelin-1, and thromboxane-B(2), and a negative correlation between interleukin-6 and thromboxane-B(2). These results suggest that concurrent challenges results in exacerbated responses of stress hormones and suggests mechanisms that could contribute to the prevalence of cardiovascular events among firefighters.

Cardiorespiratory responses of firefighters to a computerized fire strategies and tactics drill during physical activity.

Firefighters are subjected to a combination of physical and mental challenges in the course of their occupational responsibilities. However, due to the ecological factors involved with firefighting, it makes it extremely difficult to examine physiological and psychological changes that occur as a result of these combined challenges. The purpose of this study was to examine the efficacy of a computer-based Fire Strategies and Tactics Drill (FSTD) in eliciting psychological and physiological measures of stress in professional firefighters. In one session, participants exercised at 60% VO(2max) for 37 min (exercise alone condition, EAC), and in the other session the firefighter exercised for an equal amount of time and responded to the FSTD (dual challenge condition; DCC) while exercising. Cardiorespiratory (heart rate [HR], respiration rate [RR], minute ventilation [V(E)], oxygen consumption [VO(2)], ventilatory efficiency [V(E)/VO(2)], and respiratory exchange ratio [RER]) and psychometric measures (State Anxiety Inventory [SAI] and Ratings of Perceived Exertion [RPE]) were obtained throughout the experimental protocols. The NASA Task Load Index was used to assess perceived physical and mental load during each condition. The results demonstrated that the participants perceived overall workload to be higher in the DCC. Repeated measures ANOVAs revealed no differences between the EAC and DCC for VO(2) or RER, but the DCC did elicit significantly greater elevations in HR, RR, V(E), and V(E)/VO(2) compared to the EAC. These results suggest that the FSTD utilized in this study provides an effective method for examining the physiological and psychological responses of firefighters in a research laboratory environment.