Effect of cold exposure on fuel utilization in humans: plasma glucose, muscle glycogen, and lipids

• Published in: Journal of applied physiology (1985) 2002-07, Vol.93 (1), p.77-84
• Main Authors: Haman, Francois, Peronnet, Francois, Kenny, Glen P, Massicotte, Denis, Lavoie, Carole, Scott, Chris, Weber, Jean-Michel
• Format: Article
• Language: English
• Subjects: Adult; Algorithms; Area Under Curve; Biological and medical sciences; Blood Glucose - metabolism; Body Temperature - physiology; Body Temperature Regulation - physiology; Calorimetry, Indirect; Cold Temperature; Fatty Acids, Nonesterified - blood; Fundamental and applied biological sciences. Psychology; Glucose; Glycogen - metabolism; Heat; Humans; Insulin - blood; Lactic Acid - blood; Lipid Metabolism; Lipid Peroxidation; Lipids; Male; Metabolism; Metabolism - physiology; Muscle, Skeletal - metabolism; Oxidation-Reduction; Oxygen Consumption - physiology; Plasma; Thermoregulation. Hibernation. Estivation. Ecophysiology and environmental effects; Vertebrates: anatomy and physiology, studies on body, several organs or systems
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/japplphysiol.00773.2001

1  Département de Biologie and 3  École des Sciences de l'Activité Physique, Université d'Ottawa, Ottawa, Ontario K1N 6N5; 2  Département de Kinésiologie, Université de Montréal, Montréal, Québec H3C 3J7; 4  Département de Kinanthropologie, Université du Québec à Montréal, Montréal, Québec H3C 3P8; and 5  Département des Sciences de l'Activité Physique, Université du Québec à Trois-Rivières, Trois-Rivières, Québec, Canada G9A 5H7 The relative roles of circulatory glucose, muscle glycogen, and lipids in shivering thermogenesis are unclear. Using a combination of indirect calorimetry and stable isotope methodology ([U- 13 C]glucose ingestion), we have quantified the oxidation rates of these substrates in men acutely exposed to cold for 2 h (liquid conditioned suit perfused with 10°C water). Cold exposure stimulated heat production by 2.6-fold and increased the oxidation of plasma glucose from 39.4 ± 2.4 to 93.9 ± 5.5 mg/min (+138%), of muscle glycogen from 126.6 ± 7.8 to 264.2 ± 36.9 mg glucosyl units/min (+109%), and of lipids from 46.9 ± 3.2 to 176.5 ± 17.3 mg/min (+376%). Despite the observed increase in plasma glucose oxidation, this fuel only supplied 10% of the energy for heat generation. The major source of carbohydrate was muscle glycogen (75% of all glucose oxidized), and lipids produced as much heat as all other fuels combined. During prolonged, low-intensity shivering, we conclude that total heat production is unequally shared among lipids (50%), muscle glycogen (30%), plasma glucose (10%), and proteins (10%). Therefore, future research should focus on lipids and muscle glycogen that provide most of the energy for heat production. energy metabolism; shivering thermogenesis; heat loss; plasma glucose oxidation; stable isotopes