Project Aquarius 3. Effects of Work Rate on the Productivity, Energy Expenditure, and Physiological Responses of Men Building Fireline With a Rakehoe in Dry Eucalypt Forest

Abstract

Four crews of firefighters built fireline for 7 min periods (with intervening rests), without fire, at self-chosen 'slow', 'normal', and 'fast' rates in Australian eucalypt forests. Individuals differed twofold for energy expenditure (EE, measured as oxygen uptake by the Douglas bag technique) and relative work load (RWL, i.e % of maximum oxygen uptake), and threefold for productivity and efficiency (productivity per unit EE). They maintained their differences in all stages of the test and also while suppressing free-running wildland fires, showing that the work rate adopted was a stable characteristic of the individuals' work behaviour. The technique of raking fireline did not constrain EE but instead allowed firefighters to call upon their maximum work capacity for urgent tasks with no reduction in efficiency. EE, RWL, and heart rate increased linearly with productivity whereas perceived exertion and pulmonary ventilation increased curvilinearly, rising steeply at 'fast' work rates. We suggest that perceived exertion and the ventilatory threshold (the upper limit of comfortable breathing) provide the cues by which firefighters pace themselves at sustainable work rates that balance their fireline productivity against its physiological cost. The findings were highly consistent over four crews, three summers, and two regions and are thus generally applicable to bushfire suppression in southern Australia.

Impact of Different Personal Protective Clothing on Wildland Firefighters' Physiological Strain

“…Wildfire firefighting is an extremely demanding occupation (Ruby et al, 2002 ; Cuddy et al, 2015 ) that mainly takes place during the summer season. Activities performed during wildfire suppression require work with hand tools of different weight (3–20 kg) (Rodríguez-Marroyo et al, 2012 ) and they are usually performed under difficult conditions, such as inhaling smoke (Wegesser et al, 2009 ), working on steep terrain (Brotherhood et al, 1997 ) and in hot environments (Raimundo and Figueiredo, 2009 ; Rodríguez-Marroyo et al, 2012 ). Collectively, all these circumstances contribute to the high physiological strain observed during wildfires suppression (Rodríguez-Marroyo et al, 2012 ).…”

Effect of protective filters on fire fighter respiratory health during simulated bushfire smoke exposure

“…Apart from enduring heat, noise, and the stress of completing precise and physically demanding tasks [Brotherhood et al, 1997;Budd et al, 1997a,b,c,d], fire fighters are often exposed to smoke of varying densities containing elevated concentrations of irritating and toxic gases. Moreover, fire fighters are frequently confronted with situations in which they have little or no knowledge of which chemicals are present at significant levels in their surroundings.…”

Aerobic fitness impacts sympathoadrenal axis responses to concurrent challenges

“…However, responses to mental stress may be associated with increased sensitivity (greater relative increases in HR responses). Previous literature reviews have failed to reach a consensus regarding the impact of CR fitness on CR reactivity to psychological stressors (Brotherhood et al 1997;Claytor 1991;Jackson and Dishman 2006;Schuler and O'Brien 1997;Sothmann et al 1996). The evaluative function of CR fitness is complicated by the use of absolute versus relative change in pertinent variables (i.e., absolute change in HR versus relative change from baseline) and further convoluted by the use of different measures of fitness (i.e., maximal oxygen consumption, percent of maximal oxygen consumption, lactate threshold, ventilatory threshold) by various research groups.…”