Energy Cost and Energy Sources During a Simulated Firefighting Activity

Abstract

This study aimed to 1) analyze the energy requirement (VO2eq) and the contribution of the aerobic (VO2ex), anaerobic alactic (VO2al), and anaerobic lactic (VO2la-) energy sources of a simulated intervention; 2) ascertain differences in mean VO2 and heart rate (HR) during firefighting tasks; and 3) verify the relationship between time of job completion and the fitness level of firefighters. Twenty Italian firefighters (age = 32 ± 6 yr, VO2peak = 43.1 ± 4.9 mL·kg·min) performed 4 consecutive tasks (i.e., child rescue; 250-m run; find an exit; 250-m run) that required a VO2eq of 406.26 ± 73.91 mL·kg (VO2ex = 86 ± 5%; VO2al = 9 ± 3%; VO2la- = 5 ± 3%). After 30 minutes, the recovery HR (108 ± 15 beats·min) and VO2 (8.86±2.67mL·kg·min) were higher (p < 0.0001) than basal values (HR = 66 ± 8 beats·min; VO2 = 4.57 ± 1.07 mL·kg·min), indicating that passive recovery is insufficient in reducing the cardiovascular and thermoregulatory strain of the previous workload. Differences (p < 0.001) between tasks emerged for mean VO2 and HR, with a lack of significant correlation between the time of job completion and the firefighters' aerobic fitness. These findings indicate that unpredictable working conditions highly challenge expert firefighters who need adequate fitness levels to meet the requirements of their work. Practically, to enhance the fitness level of firefighters, specific interval training programs should include a wide variety of tasks requiring different intensities and decision-making strategies.

Psychophysiological Responses of Firefighters to Emergencies: A Review

“…Various studies [6,62,63] have determined that immersion in the smoke (search and rescue) is the most challenging task faced by the firefighters. Perroni et al [17] by analyzing simulated emergencies (i.e., child rescue; 250 m run; search and rescue; 250 m run) of 20 Italian firefighters have shown that VO 2 consumption of the search and rescue was 56 ± 6% compared to the total energy requirement of a simulated emergencies and was 67 ± 16% compared to VO 2max evaluated in laboratory.…”

“…HR increases during very hard work carried out for a shorter period of 15 min [9][10][11], and for a longer period [70], and remains high during the recovery phase [16,17]. Indeed, Perroni et al [17] showed that the values of HR and VO 2 increased during the simulated emergencies and they remained elevated after 30 Rodrıguez-Marroyoa et al [72] analyzed the HR of firefighters during real wildfire suppression according to the type of attack performed (direct, indirect or mixed). They found significantly higher HR in direct and mixed versus indirect attacks and demonstrated that wildfire firefighting depends on the tactics chosen for performing the task.…”

“…Various studies [1,[5][6][7][8][9][10][11][12][13][14][15][16][17] documented that the combination of physical activity, unpredictable conditions, warm clothing and/or exposure to external heat sources causes an increased physiological and psychological stress. In addition, firefighters wear protective clothing (PC) and self-contained breathing apparatus (SCBA), which are heavy, thick, multilayered and bulky (i.e., 23 kg).…”

“…Although physical stress and the workload of a real emergencies are difficult to measure, several authors have claimed that the firefighting causes a heart rate (HR) close to the maximum values [5,12,16,17] with decrease in the stroke volume [12], and increase in the core temperature [5,11,12], in the levels of blood lactate [10,16,17] and psychological stress [3,5,11,12]. For this reason, it is recognized [25,26] that firefighters must possess the physiological characteristics that enable them to respond to the emergencies.…”

Effects of Emotional Stress on Neuroendocrine and Autonomic Functions in Skydiving

“…Salivary α-amylase levels increase under stressful conditions known to increase plasma catecholamines [19][20][21][22]. The levels of α-amylase in the body have been used as an effective measure of stress, including social stress, such as performance in front of an audience [23][24][25], testing [26] ,competition [27,28], and physical stress [29][30][31]. Noninvasive measurement of activity in the SN system is also possible via skin conductance.…”