Non-shivering thermogenesis is differentially regulated during the hibernation season in Arctic ground squirrels.

Arctic ground squirrels are small mammals that experience physiological extremes during the hibernation season. Body temperature rises from 1°C to 40°C during interbout arousal and requires tight thermoregulation to maintain rheostasis. Tissues from wild-caught Arctic ground squirrels were sampled over 9 months to assess the expression of proteins key to thermogenic regulation.

Negative Energy Balance Does Not Alter Fat-Free Mass During the Yukon Arctic Ultra-The Longest and the Coldest Ultramarathon.

The objective of this study was to determine alterations in caloric balance, body composition, metabolites, and cytokines in athletes participating in the Yukon Arctic Ultra. Ten participants traveling on foot in the 2017 692-km event were recruited for the study. Measurements and samples were obtained at pre-event, 278 km (C1), 384 km (C2), and post-event.

Essential amino acid-enriched meal replacement promotes superior net protein balance in older, overweight adults.

Background & Aims: Older individuals are susceptible to the loss of muscle and accumulation of fat. To address this problem, we have compared protein kinetics following consumption of an essential amino acid (EAA)-enriched meal replacement (EMR) to consumption of a high-protein meal replacement beverage (Bariatric Advantage, BA) using stable isotope methodology.

Methods: Eight older (67 ± 2), obese (35 ± 2 kg/m) female and male participants completed two studies using a randomized, crossover design in which they ingested each meal replacement.

Alaska Mountain Wilderness Ski Classic: Alterations in Caloric Expenditure and Body Composition.

Introduction: The Alaska Mountain Wilderness Ski Classic is a self-supported ultramarathon cross-country skiing event that traverses one of the mountain ranges of Alaska each winter. Unique aspects of this event challenge athletes with a significant amount of physical and mental stress while in the chronically cold conditions of the Arctic. Assessment of energy requirements or body composition has never been performed during this event.