Hot water immersion acutely increases postprandial glucose concentrations.

Christof A Leicht,Jane H B Briscoe,Sven P Hoekstra,Lewis J James

doi:10.14814/phy2.14223

Christof A Leicht, Jane H B Briscoe + Show 2 more

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https://doi.org/10.14814/phy2.14223

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Journal: Physiological Reports	Publication Date: Oct 1, 2019
Citations: 19	License type: CC BY 4.0

Affiliation: Loughborough University

Abstract

Chronic hot water immersion (HWI) confers health benefits, including a reduction in fasting blood glucose concentration. Here we investigate acute glycemic control immediately after HWI. Ten participants (age: 25 ± 6 years, body mass: 84 ± 14 kg, height 1.85 ± 0.09 m) were immersed in water (39°C) to the neck (HWI) or sat at room temperature (CON) for 60 min. One hour afterward they underwent an oral glucose tolerance test (OGTT), with blood collected before and after HWI/CON and during the 2 h OGTT. Glucose incremental area under the curve (iAUC) during the OGTT was higher for HWI (HWI 233 ± 88, CON 156 ± 79 mmol·L−1·2 h, P = 0.02). Insulin iAUC did not differ between conditions (HWI 4309 ± 3660, CON 3893 ± 3031 mU·L−1·2 h, P = 0.32). Core temperature increased to 38.6 ± 0.2°C during HWI, but was similar between trials during the OGTT (HWI 37.0 ± 0.2, CON 36.9 ± 0.4°C, P = 0.34). Directly following HWI, plasma average adrenaline and growth hormone concentrations increased 2.7 and 10.7‐fold, respectively (P < 0.001). Plasma glucagon‐like peptide‐1, peptide YY, and acylated ghrelin concentrations were not different between trials during the OGTT (P > 0.11). In conclusion, HWI increased postprandial glucose concentration to an OGTT, which was accompanied by acute elevations of stress hormones following HWI. The altered glycemic control appears to be unrelated to changes in gut hormones during the OGTT.

Highlights

Increasing body temperature, by using hot water immersion (HWI) (Brunt et al 2016; Hoekstra et al 2018) or sauna bathing (Imamura et al 2001; Biro et al 2003; Laukkanen et al 2015), can reduce risk markers related to inflammation and cardiovascular health
Glucose incremental area under the curve (iAUC) during the oral glucose tolerance test (OGTT) was higher for HWI (HWI 233 Æ 88, control trial (CON) 156 Æ 79 mmol LÀ1Á120 min, P = 0.02, Fig. 1)
This was due to a higher iAUC in HWI in the second hour of the OGTT (P = 0.05); iAUC in the first hour of the OGTT did not differ between conditions (P = 0.73)

Summary

Introduction

By using hot water immersion (HWI) (Brunt et al 2016; Hoekstra et al 2018) or sauna bathing (Imamura et al 2001; Biro et al 2003; Laukkanen et al 2015), can reduce risk markers related to inflammation and cardiovascular health. Chronic HWI interventions further show improvements in glucose tolerance in rats being fed a high-fat diet (Gupte et al 2009), and a normalization of glucose excursions in Vervet monkeys (Kavanagh et al 2016). These chronic effects of HWI are similar to responses observed following exercise training (Kr€ankel et al 2019). Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society

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