Physiological responses and parasympathetic reactivation in rescue interventions: The effect of the breathing apparatus

This study aimed to assess the effect of wearing a breathing apparatus during a simulated rescue intervention on psychophysiological responses and parasympathetic reactivation of firefighters. Thirty-four firefighters participated in this study which consisted of four experimental sessions conducted randomly: a maximal fitness test and three rescue interventions performed (a) with personal protective clothing (PPC); (b) with PPC and the full self-contained breathing apparatus (SCBA), including cylinder, full-face piece, and breathing regulator; and (c) with PPC and only the cylinder of the self-contained breathing apparatus (SCBAc). Physiological (heart rate [HR], breathing frequency [BF]) and perceptual (rating of perceived exertion [RPE]) responses were continuously collected during the three rescue interventions. Parasympathetic reactivation was assessed using HR recovery and variability indexes after experimental sessions. HR responses ranged between 63% and 95% of HRmax, and BF responses ranged between 22 and 55 breaths/min for the different activity tasks. Parasympathetic reactivation indexes were similar for the rescue interventions but lower than after the intermittent fitness test (P = 0.016 - P < 0.0001). Mean HR for both SCBAc (83.2 +/- 4.1%HRmax) and SCBA (83.1 +/- 5.2%HRmax) was higher in comparison with PPC (79.5 +/- 5.3%HRmax). RPE was higher for SCBA than for SCBAc which was higher than PPC. Mean BF for SCBA (34 breaths/min) was lower than PPC (40 breaths/min) and SCBAc (43 breaths/min). Based on HR, BF, and RPE, rescue interventions seem to be psychologically and physiologically stressful. Parasympathetic reactivation after PCC, SCBA, and SCBAc suggests that these conditions induce higher cardiac stress than the maximal fitness test. The study showed that SCBA increased psychophysiological perturbations.