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The general response to acute cold stress is vasoconstriction and increased heat production (M) via shivering. Both skin and internal body temperatures (Tc) must be lower than a fixed threshold before shivering (ΔM = M-Mbasal) occurs. Several thermoregulatory models include ΔM algorithms as a ƒ(Tc, Tsk). Other models include ΔM as a ƒ(% body fat (%BF), lean body mass (LBM)). We examined how well 3 models predict ΔM for a given cold stress in a data set of resting women and men prior to their sojourn for a year in Antarctica. Six women and 29 men (%BF ranges 10-46%) resting semi-supine, unclothed except for underwear + smock (RT =0.022 m2·K·W-1), were exposed for 2 h to cold air. Fifteen men and 5 women completed a cold stress test (CST group: Ta=5.7±0.6SD °C;rh = 50%;V=0.2m·s-1) and a separate group of 14 men and 1 woman completed a cool test (Cool group: Ta = 8.4±1.3SD °C). Extensive peripheral (Tsk and finger temperatures) vasoconstriction occurred during the CST and less so in the Cool, elevating mean resting temperature pill level (Tc) by +0.15-0.2°C for the first 30min followed by a mean decline in Tc of -0.01°C/min. ΔM (W·m-2) at 5 time points was compared against 3 model predictions: (1) Tikuisis and Giesbrecht (Tik-G), 1999: ΔM = 156·(37-Tc) + 47·(33- Tsk) - 1.57·(33- Tsk)2 ·%BF-0.5; (2) Stolwijk and Hardy (S-H), 1977: ΔM = [13·(Tc -37) +0.4·(Tsk-34)]·(Tsk-34) and (3) Tikuisis et al., (Tik), 1991: ΔM/LBM = {0.0422·(35.4-Tsk)2}/(%BF)0.506. Root mean square deviation (RMS) comparing ΔM vs each model output is shown in the Table.
| Data vs Model |
RMS (W·m-2)
Men (N=14) |
RMS (W·m-2)
Men(N=15) |
RMS (W·m-2)
Women (N=5) |
| obsΔM vs Tik-G |
28.4±8.2
Cool group |
26.6±13.2**
CST group |
29.6±15.1
CST group |
| obsΔM vs S-H |
23.2±16.3
Cool group |
34.9±14.1**
CST group |
33.8±15.6
CST group |
| obsΔM vs Tik † |
23.7±15.7
Cool group |
22.9±9.3
CST group |
15.2±3.1
CST group |
[**RMS Comparison between models P<0.0001; all others NS. †Normalized to W·m-2. No women in Cool group]. RMS from the Tik-G was < then the S-H prediction in the CST group of men. All predictions were equal in RMS in the Cool groups. For %BF ≤ 20%, Tik-G was highly correlated with integrated mean body temperature (Tb,I) derived from partitional calorimetry (R2=0.89; P<0.001; ΔM(Tik-G) = -33.5·(Tb,I) + 1226). ΔM calculated from cold-air models incorporating %BF, Tc and Tskinputs serve as reliable predictors of shivering response over a limited cold stress for both men or women.
Stolwijk, J.A.J., and Hardy, J.D., 1977. Control of body temperature. In:Handbook of Physiology-Reactions to Environmental Agents. Am.Physiol. Society, Rockville, MD, Chapter 4, pp 45-68.
Tikuisis, P., and Giesbrecht, G.G. , 1999. Prediction of shivering heat production from core and mean skin temperatures. Eur. J. Appl. Physiol. 66,221-229.
Tikuisis,P, Bell, D.G., and Jacobs, I., 1991. Shivering onset, metabolic response, and convective heat transfer during cold air exposure. J.Appl. Physiol. 70,1996-2002.