Selected hormonal and immunological responses to strenuous live-fire firefighting drills

Abstract

This study investigated the effects of strenuous live-fire firefighting drills and a 90 min recovery period on selected hormonal, immunological and psychological variables. Apparently healthy, male, professional firefighters (n = 11) performed three trials of standardized firefighting tasks in a live-fire training structure. There was significant leukocytosis immediately post firefighting activity that persisted following recovery, although there was a variable response among the leukocyte subsets. Most notable was the decrease in number and percentage of lymphocytes following 90 min of recovery. Plasma levels of ACTH and cortisol were significantly elevated post firefighting activity and cortisol remained elevated following 90 min of recovery. Elevated cortisol immediately following activity was related to reduced feelings of energy. These data demonstrate the magnitude of the physiological and psychological disruption following strenuous firefighting activity and suggest that immune function may be altered following such activity. This is a finding that may have practical consequences for this group of first responders.

Acute effects of firefighting on arterial stiffness and blood flow

“…To our knowledge, this is the first study to examine arterial stiffness under such conditions. Short-term fire-suppression activities have been shown to elevate core temperature as well as decrease plasma volume 7 and stroke volume. 4 We observed an average increase in core temperature of > 2°C, which is twice as great as seen after aerobic exercise.…”

“…4,5 Environmental conditions involving live fire and high ambient temperatures 6 coupled with strenuous activity in fully encapsulating firefighting personal protective equipment cause substantial elevations in core temperature following even short-term firefighting activity. 4,7 Intense physical exertion has independently been shown to trigger sudden cardiovascular events, particularly in those who are sedentary. 8 It is thought that the combination of high levels of heat stress and physical exertion lead to sudden cardiac events in susceptible firefighters.…”

Physiological Determinants of the Candidate Physical Ability Test in Firefighters

“…Heart rates in excess of 95% of maximum (53,55,72,74,89,92), rates of oxygen consumption approaching maximal oxygen uptake (VO 2 max) (10,34,89,92), and significant activation of the sympathoadrenal axis (64,76) have been recorded during simulated or live firefighting tasks. Thus, fire fighting suppression activities may be a significant physiological stress and high levels of fitness are required by the firefighter.…”

Physiological and psychological responses in Fire Instructors to heat exposures

“…The effects of simulated acute heat exposures may reduce immune function, in the short 27 term, (Sheppard et al 1986;Smith et al 2005) and it is likely to have longer term 28 consequences, especially if there is insufficient time for recovery between bouts of heat 29 exposure. As well as this firefighting personnel appear to be at greater risk of 30 respiratory (Sheppard et al 1986) and cardiovascular diseases (Fernhall et al 2012) (Sheppard et al 1986;Fernhall et al 2012).…”