Determination Of Total Energy Expenditure Of Dog Sled Drivers During A 1049-mile Iditarod Race

Abstract

The Iditarod dog sled race provides a unique opportunity to study the rate of human energy expenditure during extended exercise with the added challenges of sleep deprivation, extreme cold and the management of a large team of dogs. In addition, the distribution of macronutrients and the fitness of the driver are important in order to guide the team through steep and icy conditions during a multi-day race. PURPOSE The purpose of this study was threefold: (a) to assess the total energy expenditure (TEE) of the musher, (b) to determine the distribution of macronutrients ingested during the race and (c) to estimate the fitness level of the dogsled driver (musher) prior to the race. METHODS Five mushers from the Iditarod sled dog race were recruited as research subjects to receive doubly labeled water, with three agreeing to monitor food intake. Four out of the five subjects completed the entire race. Pre-race estimate of aerobic fitness (VO2peak) using a multi-stage bench stepping protocol were also determined. RESULTS Doubly labeled water data demonstrated an average TEE of 20.8 MJ·d−1 (4972 kcal·d−1) from Anchorage to Nome for our male subject, with an average of 11.8±1.7 MJ·d−1 (2808±397 kcal·d−1) for the female subjects during the race. Food records suggested an average distribution of macronutrients of 1.5±0.4, 3.9±0.4 and 1.7±0.9 g·kg−1 for protein, carbohydrates and fats, respectively. Estimated VO2peak was 66.2 ml·kg−1·min−1 and 50.0±8.4 ml·kg−1·min−1 for the male (n = 1) and female subjects (n = 4), respectively. CONCLUSION These data demonstrate that dogsled drivers, with an above average estimated VO2peak, maintain consistent, high daily total energy expenditure (TEE) throughout all phases of the race.