The medium-term changes in performance and physiological and anthropometric characteristics following prolonged...

This study investigated the performance, physiological, and anthropometric changes in a 28-year-old female following an 1130 km Antarctic ski expedition. Data showed that the participant performed low-intensity ski trekking (LIST, ∼62% maximal heart rate) ∼9 h·day^-1 for 46 days of the total of 49 expedition days. Estimations indicated that the mean energy intake during the trek (∼15 MJ·day^-1/∼3589 kcal·day^-1) was ∼75% greater than that prior to the event (∼8.6 MJ·day^-1/∼2048 kcal·day^-1), and dietary energy distribution of carbohydrates, fats, and proteins changed from a ∼53/30/17 ratio pre-expedition to a ∼43/48/9 ratio during it. Body mass decreased by 11%, while lean mass was maintained. Time to exhaustion during a short (∼5 min) and long (>40 min) incremental ski trek simulation on a treadmill increased by 29% and 3.6%, respectively. Absolute V̇O_2max (L·min^-1) was unchanged, but relative V̇O_2max (mL·kg^-1·min^-1) increased by 17%. Blood glucose concentration decreased by 8.5%, while lipid levels increased by 11%-35%. Creatine kinase, aspartate aminotransferase, and alanine aminotransferase decreased by 21%, 18%, and 13%, respectively. Thyroid stimulating hormone (TSH) increased by 59%. In conclusion, medium-term prolonged LIST can lead to weight-induced endurance performance enhancement and may improve muscle cell resiliency. A low protein intake during such an event does not appear to affect lean mass negatively, despite a substantial weight loss. Reduced carbohydrate consumption and increased fat intake in relative (%) terms during a medium-duration ski trek can decrease blood glucose concentration and raise lipid levels, respectively. TSH may remain elevated several days after such an expedition, reflecting raised metabolism.