A Revised Algorithm for Estimating Energy Expenditure in Wildland Firefighters with the CSA Activity Monitor

Purpose This study was designed to evaluate the efficacy of a revised algorithm (Heil MSSE 33:S 168, 2001) for transforming data from CSA activity monitors (Model 7164-1.2) into measures of workshift activity (EEACT, kcals shift4) and total (EETQT, kcalsdaf1) energy expenditure in wild land firefighters during extended periods of actual wild land fire suppression.

Methods Two groups of 15 wild land firefighters (Group 1: 4M, 1 F; Group 2: IOM) from different Interagency Hotshot crews volunteered to carry CSA activity monitors in the chest pocket of their work shirts for five (Group 1) or nine (Group 2) consecutive days. The CSA’s were mounted to plastic cards the maintained the monitors’ vertically relative to the torso.. A custom Visual Basic program read the raw GSA data files (1 min epochs) and transformed each data point> 250 counts min for each full work shift (5 days subject) into kcalsmirr1, where kcaismirr1 = (METs) x (0.0175 kcalskg1min T’MET1) x (kg body mass 16 kg pack), and METs wee derived using the Swartz et al, equation (MSSE 32:S450-S456, 2000). Data points < 250 countsmiW1 were assumed to be at 1. 1 METs during rest and 0.9 METs while sleeping (self-reported) EEACT was computed as the sum of activity and resting values during the work shift while EBTOT was the sum of EEACT, sleep EE, non-shift resting EE, and an assumed 10% for dietary induced thermogenesis.

Results Work shift duration was (Mean ± SD) 13.5 ± 0.1 and 13.3 ± 0.5 hours for groups 1 and 2, respectively.

Conclusions Values for EEACT and EETOT are higher than those reported previously by Hell (2001), and slightly higher than reported