Changes in metabolic energy measures for daily living activities and exercise in men and women following arduous activity in Antarctica

Abstract

This study reports pre- to post-expedition (pre|post) changes in energy expenditure and substrate utilisation during daily living activities (DLAs including rest, sleep, modest exercise, sedentary work and leisure) and maximum aerobic power (V̇O2max) for participants in the Inspire-22 expedition (6 men, 3 women) who undertook a 47 day unassisted Antarctic traverse from the Ronne Ice Shelf to the South Pole. DLA measurements were carried out during a 36 hour study in a whole-body calorimeter whilst measurements of maximum oxygen uptake (V̇O2max), capillary glucose and lactate during incremental stepping exercise to volitional exhaustion were carried out under normobaric normoxic and hypoxic (14% O2) conditions in an environmental chamber. Non-exercise measures were normalised to non-fat tissue weight; exercise measures, including those in the DLAs, to body weight. Statistical analysis used the Aligned Rank Transform (ART) non-parametric ANOVA technique with covariants pre|post expedition, sex and hypoxia|normoxia as appropriate. There were no systematic differences between pre- and post-expedition energy expenditure but significant differences between men and women for the majority of the DLAs (p<0.05). There was increased carbohydrate utilisation post-expedition for sleep and the two lower intensity exercise levels (p<0.05) but not during rest or the highest intensity exercise (p>0.05); a sex-independent subset of 4 showing much higher utilisation. Women had a lower protein utilisation than men during the DLA exercise activities (p<0.05). V̇O2max was lower in hypoxia than normoxia (p<0.001) and reduced glucose and lactate between pre- and post-expedition measures. There was also a significant interaction between sex and pre|post measurements for V̇O2max and lactate suggesting that adaptation to the environment and high workloads was different between men and women; a suggestion supported by the difference in fat-free tissue measured pre- and post-expedition, but neither sex showed major differences between the pre- and post-expedition measurements.