ISSN:
1439-6327
Keywords:
Body temperatures
;
Energy metabolism
;
Heat balance
;
Heat production
;
Human
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary Energy substrate mobilization has been suggested as being a limiting factor for the rate of cold-induced thermogenesis (M), and consequently in delaying hypothermia. The evidence supporting this hypothesis in humans, however, is not convincing and the hypothesis has yet to be tested in a rigorous manner using a full heat balance analysis (partitional calorimetry). The goal of this study was therefore to re-investigate whether enhancing energy substrate mobilization by feeding cold-exposed subjects would improveM and affect heat debt (S; the minute-by-minute balance ofM and heat losses) as well as rectal (T re) and mean skin temperatures $$\bar T_{sk} $$ . Nine healthy semi-nude fasted subjects were exposed to 5° C (3 h at rest, 1 m · s−1 wind) on three occasions following the ingestion at min 0 and 90 of either: (1) a placebo, (2) 710 kJ of pure carbohydrates (100%-CHO), or (3) 710 kJ of a high-carbohydrate bar (High-CHO). As expected in the cold,T re andT sk decreased whereasM, S and heat losses increased (P〈0.01). However, there were no differences between treatments, including the finalT re [mean (SEM); 36.4 (0.2); 36.5 (0.3) and 36.5 (0.2)°C for the placebo, 100%-CHO and High-CHO tests, respectively]. During the 100%-CHO treatment, rates of carbohydrate oxidation were the highest and fat oxidation the lowest (P〈0.05), whereas the High-CHO treatment caused smaller changes. The results demonstrate that in the cold, enhancing energy substrate mobilization by ingesting substrates in the form of a supplement containing either mainly or only CHO does not cause detectable changes inM, heat loss,S or body temperatures, compared to the ingestion of a placebo. Under the present conditions, the results do not support the theory that energy substrate mobilization is a limiting factor for cold-induced thermogenesis in humans.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00864222
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