Análise dinâmica da resposta metabólica e desempenho de bombeiros militares durante tarefa simulada de resgate de vítima em ocorrência de incêndio em edifício: subidas de escada em ritmo autosselecionado e velocidade crítica operacional

Abstract

Purpose: The objective of this study was to analyze the influence of the pace of stair climbing on the metabolic performance of firefighters when rescuing a victim in a building. Methodology: Ventilation per minute (VE), oxygen consumption (VO2), metabolic equivalent (MET), carbon dioxide output (VCO2), respiratory exchange ratio (RER = VCO2/VO2), heart rate (HR) and oxygen pulse (PuO2 = VO2/HR) were examined with the portable metabolic system; performance responses in the rescue; rating of perceived exertion (RPE) and musculoskeletal pain and discomfort in 18 participants, male military firefighters, selected for convenience. First, they performed a maximal ergospirometry test and then they were distributed through a randomized and balanced draw in the other phases of tests: a) Stair climbing tests at a self-selected personal pace (Auto) as fast as possible and b) Stair climbing tests at a critical speed (VC) pace. The times obtained at distances of 10 and 20 floors (2nd phase) were submitted to the linear regression procedure to determine the critical operational speed (slope coefficient) using the equation VC = [(N20 – N10) / (t20 – t10)]. Results: The ergospirometry test revealed a peak oxygen consumption (VO2peak) of 56.2 ± 11.5 ml.kg-1. Min-1 (mean ± SD). In the Auto 10, Auto 20, VC 10 and VC 20 tests, VO2peak was 52.8± 8.4; 57.3 ± 8.4; 51.0 ± 10.0 and 51.7 ± 8.0 ml. kg-1. Min-1 (95.8%; 103.5%; 92.1% and 93.8% of VO2peak) respectively and Hrpeak was 164.0 ± 17.0; 170.1 ± 21.5; 160.0 ± 10.8 and 169.4 ± 11.4 bpm (90.6%, 93.9%, 88.4% and 93.5% of Hrpeak), respectively. The three-way repeated measures ANOVA, considering the significance level at p ≤ 0.05, showed that if the firefighter climbs at a critical operational speed, the firefighter will have a better performance on the floor of the accident, since the rescue time (seconds) was 50.65 ± 14.01 and 56.00 ± 14.24 for VC 10 and VC 20 vs 58.91 ± 11.86 and 70.28 ± 19.27 for Auto 10 and Auto 20, respectively. In addition, overall the difference in the average drag speed between 10 and 20 floors climbing at the selfselected speed was 7.7%, while at VC it was 3%. The RPE in VC 10 < Auto 10 at the end of the ascent (p = 0.017) and after rescue (p = 0.001). After recovery, musculoskeletal pain and discomfort in the middle back and lower back regions in the Auto 10 > Auto 20 and in the VC 10 test was greater in the right ankle, right foot, and left foot. Conclusion: The pace of climbing stairs to rescue a victim interferes with the firefighter’s metabolic responses; the time of stair climbing and the total time were shorter in the self-selected strategy; the rescue speed was higher when the VC was adopted and climbing twenty floors in the self-selected strategy requires a higher VO2, revealing that the critical operational speed seems to be an adequate alternative for stair climbing pace.