http://orcid.org/0000-0003-4688-7252
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ABSTRACT
Increasing physical activity remains the most widely publicized way of improving health and wellbeing. However, in populations that benefit most from exercise (EX), adherence is often poor and alternatives to EX are important to bring about health improvements. Recent work suggests a role for passive heating (PH) and heat shock proteins (HSP) in improving cardio-metabolic health. The aim of this study was to investigate the expression of HSP70 and interleukin-6 in response to either EX or PH and the subsequent effect on glucose control. Fourteen males volunteered and were categorized lean (BMI 23.5 ± 2.2 kg·m−2) or overweight (29.2 ± 2.7 kg·m−2) and completed 60 minutes of either moderate cycling at a fixed rate of metabolic heat production (EX) or warm water immersion in 40°C water (PH). Extracellular HSP70 increased from baseline in both conditions with no differences between PH (0.98 ± 1.1 ng·mL−1) or EX (0.84 ± 1.0 ng·mL−1, p = 0.814). IL-6 increased following both conditions with a two-fold increase after PH and four-fold after EX. Energy expenditure increased by 61.0 ± 14.4 kcal·h−1 (79%) after PH. Peak glucose concentration after a meal immediately following PH was reduced when compared with EX (6.3 ± 1.4 mmol·L−1 versus 6.8 ± 1.2 mmol·L−1; p < 0.05). There was no difference in 24-hour glucose area under the curve (AUC) between conditions. These data indicate the potential for thermal therapy as an alternative treatment and management strategy for those at risk of developing metabolic disease where adherence, or ability to EX, may be compromised.
Abbreviations
| AMPK | = | 5′ adenosine monophosphate-activated protein kinase |
| AUC | = | Area under the curve |
| BMI | = | Body mass index |
| BP | = | blood pressure |
| BSA | = | body surface area |
| CGM | = | Continuous glucose monitor |
| CI | = | confidence interval |
| CV | = | coefficient of variation |
| eHSP | = | extracellular heat shock protein |
| ELISA | = | enzyme-linked immunosorbent sandwich assay |
| ES | = | effect size |
| EX | = | Exercise trial |
| HDL-C | = | High-density lipoprotein cholesterol |
| = | Metabolic heat production | |
| HSP | = | Heat shock protein |
| iHSP | = | Intracellular heat shock protein |
| IL-1ra | = | Interleukin 1 receptor antagonist |
| IL-6 | = | Interleukin 6 |
| IL-10 | = | Interleukin 10 |
| JNK | = | c-Jun N-terminal kinase |
| LDL-C | = | Low density lipoprotein cholesterol |
| LEAN | = | Lean participant group |
| OW | = | Overweight participant group |
| PH | = | Passive heating trial |
| SD | = | Standard deviation |
| SEM | = | Standard error of mean |
| T2DM | = | Type 2 diabetes mellitus |
| Tb | = | body temperature |
| Tc | = | core temperature |
| Tm | = | muscle temperature |
| Tsk | = | skin temperature |
| TG | = | Triglyceride |
| = | carbon dioxide production | |
| = | oxygen uptake | |
| = | Maximum volume of oxygen uptake | |
| ΔT | = | change in temperature |
Disclosure of potential conflicts of interest
No potential conflicts of interest were disclosed.
Acknowledgments
The authors would like to thank; Prof George Havenith for granting access to the Environmental Ergonomics Research Centre and Dr Caroline Smith for her insightful discussion and comments during the preparation of the manuscript.
Funding
The research was also partly supported by the National Institute for Health Research (NIHR) Diet, Lifestyle & Physical Activity Biomedical Research Unit based at University Hospitals of Leicester and Loughborough University. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health.
