In Reply to Drs McAnaney and Ganti

To the Editor:

We thank Drs McAnaney and Ganti¹ for their interest in and attention to our recent publication in Wilderness & Environmental Medicine.² Their letter to the editor raised some important points. We appreciate the chance to address some of their concerns.

We agree that these data perhaps most accurately describe the energy cost of wildland firefighting. Not only did we collect data in the field on a wide range of crews, but our data also fit within other data from the literature.^3,4 Nonetheless, there were constraints. We agree that predicting energy expenditure via the Pandolf equation was one of these limitations. However, there were only a few published estimation equations available for us to use, and we had to make a best choice. The challenge was that wildland firefighters hike with significantly more load and up higher grades, so their energy expenditures are higher than most equations capture, as was pointed out. We also considered using a recently published equation,⁵ but this equation would not allow us to include a terrain factor. In the end, we predicted the energy expenditure via 3 different estimation equations (ACSM, Pandolf, Ludlow), and we did not find drastic differences. The estimation was slightly out of the range of the original Pandolf equation for the training hike data only. Thus, we feel confident in our energy expenditure estimates for the ingress and egress hike data, the premises for most of our conclusions from this research.

Although we do not dispute that altitude can affect the physiological response to wildland firefighting, we do not feel that it significantly affected this particular data. Global positioning system data for each subject indicated that altitudes averaged 1505±706 (max 3326) m. This elevation would not significantly affect the estimated energy expenditure, which was our primary focus.

We agree that smoke inhalation is also a risk for the wildland firefighters, and in fact, we have published articles on its physiological effects.^6,7 We did not collect specific particulate matter data for the subjects in the current study; therefore, we are unable to speculate on their effects. We are looking at smoke exposure in a separate study and will publish that data in the near future. Nonetheless, there was no reason for us to believe that degree of exposure had a significant effect on energy expenditures estimates for firefighters hiking in the field.

In regard to the last point, we were limited to discussing our data as they related to previously published research. To encompass all the risks to wildland firefighter would go well beyond the scope of what we measured. We are certainly interested in aiding wildland firefighter preparedness; however, the total risk profile can only be addressed in the form of original research in small increments. We are currently pursuing other avenues to address risks to wildland firefighters, such as smoke inhalation, rhabdomyolysis, nutritional and hydration needs, and more. Again, we thank the editors and letter of interest to our study on the metabolic demands of wildland firefighting.

References

McAnaney

Ganti

In response to metabolic demand of hiking in wildland firefighting by Sol et al. Wilderness Environ Med 2019; 30(2), 217.

Sol

J.A.

Ruby

B.C.

Gaskill

S.E.

Dumke

C.L.

Domitrovich

J.W.

Metabolic demand of hiking in wildland firefighting. Wilderness Environ Med 2018; 29(3), 304–314.

Ruby

B.C.

Shriver

T.C.

Zderic

T.W.

Sharkey

B.J.

Burks

Tysk

Total energy expenditure during arduous wildfire suppression. Med Sci Sports Exerc 2002; 34(6), 1048–1054.

Cuddy

J.S.

Sol

J.A.

Hailes

W.S.

Ruby

B.C.

Work patterns dictate energy demands and thermal strain during wildland firefighting. Wilderness Environ Med 2015; 26(2), 221–226.

Ludlow

Weyand

Walking economy is predictably determined by speed, grade, and gravitational load. J Appl Physiol 2017; 123, 1288–1302.

Peters

Ballmann

Quindry

Zehner

E.G.

McCroskey

Ferguson

et al. Experimental woodsmoke exposure during exercise and blood oxidative stress. J Occup Environ Med 2018; 60(12), 1073–1081.

Ferguson

M.D.

Semmens

E.O.

Dumke

Quindry

J.C.

Ward

T.J.

Measured pulmonary and systemic markers of inflammation and oxidative stress following wildland firefighter simulations. J Occup Environ Med 2016; 58(4), 407–413.