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Oxidative fuel selection and shivering thermogenesis during a 12- and 24-h cold-survival simulation
- Source :
- Journal of Applied Physiology. 120:640-648
- Publication Year :
- 2016
- Publisher :
- American Physiological Society, 2016.
-
Abstract
- Because the majority of cold exposure studies are constrained to short-term durations of several hours, the long-term metabolic demands of cold exposure, such as during survival situations, remain largely unknown. The present study provides the first estimates of thermogenic rate, oxidative fuel selection, and muscle recruitment during a 24-h cold-survival simulation. Using combined indirect calorimetry and electrophysiological and isotopic methods, changes in muscle glycogen, total carbohydrate, lipid, protein oxidation, muscle recruitment, and whole body thermogenic rate were determined in underfed and noncold-acclimatized men during a simulated accidental exposure to 7.5°C for 12 to 24 h. In noncold-acclimatized healthy men, cold exposure induced a decrease of ∼0.8°C in core temperature and a decrease of ∼6.1°C in mean skin temperature (range, 5.4-6.9°C). Results showed that total heat production increased by approximately 1.3- to 1.5-fold in the cold and remained constant throughout cold exposure. Interestingly, this constant rise in Ḣprod and shivering intensity was accompanied by a large modification in fuel selection that occurred between 6 and 12 h; total carbohydrate oxidation decreased by 2.4-fold, and lipid oxidation doubled progressively from baseline to 24 h. Clearly, such changes in fuel selection dramatically reduces the utilization of limited muscle glycogen reserves, thus extending the predicted time to muscle glycogen depletion to as much as 15 days rather than the previous estimates of approximately 30–40 h. Further research is needed to determine whether this would also be the case under different nutritional and/or colder conditions.
- Subjects :
- Adult
Blood Glucose
Male
Physiology
Cold exposure
030209 endocrinology & metabolism
Shivering thermogenesis
Oxidative phosphorylation
Biology
Body Temperature
Young Adult
03 medical and health sciences
Oxygen Consumption
0302 clinical medicine
Physiology (medical)
Dietary Carbohydrates
Humans
Muscle, Skeletal
Selection (genetic algorithm)
Shivering
Thermogenesis
030229 sport sciences
Lipid Metabolism
Lipids
Cold Temperature
Biochemistry
Energy Metabolism
Skin Temperature
Oxidation-Reduction
Glycogen
Body Temperature Regulation
Subjects
Details
- ISSN :
- 15221601 and 87507587
- Volume :
- 120
- Database :
- OpenAIRE
- Journal :
- Journal of Applied Physiology
- Accession number :
- edsair.doi.dedup.....47029eb303cf3aa908d02ebe2f1be5fe