Repeated core temperature elevation induces conduit artery adaptation in humans

Key pointsr A recent 30 year prospective study showed that lifelong sauna use reduces cardiovascular-related and all-cause mortality; however, the specific cardiovascular adaptations that cause this chronic protection are currently unknown.r We investigated the effects of 8 weeks of repeated hot water immersion ('heat therapy') on various biomarkers of cardiovascular health in young, sedentary humans.r We showed that, relative to a sham group which participated in thermoneutral water immersion, heat therapy increased flow-mediated dilatation, reduced arterial stiffness, reduced mean arterial and diastolic blood pressure, and reduced carotid intima media thickness, with changes all on par or greater than what is typically observed in sedentary subjects with exercise training.r Our results show for the first time that heat therapy has widespread and robust effects on vascular function, and as such, could be a viable treatment option for improving cardiovascular health in a variety of patient populations, particularly those with limited exercise tolerance and/or capabilities. AbstractThe majority of cardiovascular diseases are characterized by disorders of the arteries, predominantly caused by endothelial dysfunction and arterial stiffening. Intermittent hot water immersion ('heat therapy') results in elevations in core temperature and changes in cardiovascular haemodynamics, such as cardiac output and vascular shear stress, that are similar to exercise, and thus may provide an alternative means of improving health which could be utilized by patients with low exercise tolerance and/or capabilities. We sought to comprehensively assess the effects of 8 weeks of heat therapy on biomarkers of vascular function in young, sedentary subjects. Twenty young, sedentary subjects were assigned to participate in 8 weeks (4-5 times per week) of heat therapy (n = 10; immersion in a 40.5°C bath sufficient to maintain rectal temperature ࣙ 38.5°C for 60 min per session) or thermoneutral water immersion (n = 10; sham). Eight weeks of heat therapy increased flow-mediated dilatation from 5.6 ± 0.3 to 10.9 ± 1.0% (P < 0.01) and superficial femoral dynamic arterial compliance from 0.06 ± 0.01 to 0.09 ±0.01 mm 2 mmHg −1(P = 0.03), and reduced (i.e. improved) aortic pulse wave velocity from 7.1 ± 0.3 to 6.1 ± 0.3 m s −1(P = 0.03), carotid intima media thickness from 0.43 ± 0.01 to 0.37 ± 0.01 mm (P < 0.001), and mean arterial blood pressure from 83 ± 1 to 78 ± 2 mmHg (P = 0.02). No changes were observed in the sham group or for carotid arterial compliance, superficial femoral intima media thickness or endothelium-independent dilatation. Heat therapy improved endothelium-dependent dilatation, arterial stiffness, intima media thickness and blood pressure, indicating improved cardiovascular health. These data suggest heat therapy may provide a simple and effective tool for improving cardiovascular health in various populations.

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“…; Carter et al . a ), suggesting that passive heat therapy may induce long‐term CV protective effects through similar mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Passive heat therapy improves endothelial function, arterial stiffness and blood pressure in sedentary humans

Brunt

Howard

Francisco

et al. 2016

The Journal of Physiology

212

264

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“…Several studies have explored the impact of repeated exposure to elevations in antegrade shear stress via training, heating, or in vitro manipulation of antegrade shear 7, 13, 14, 15, 16, 17. These studies consistently report a dose‐dependent increase in arterial caliber and improvement in endothelial function, possibly through upregulation of endothelial nitric oxide synthase 1, 18.…”

Section: Introductionmentioning

confidence: 99%

Impact of 2‐Weeks Continuous Increase in Retrograde Shear Stress on Brachial Artery Vasomotor Function in Young and Older Men

Thijssen

Schreuder²,

Newcomer

et al. 2015

JAHA

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BackgroundAlthough acute elevation in retrograde shear rate (SR) impairs endothelial function, no previous study has explored the effect of prolonged elevation of retrograde SR on conduit artery vascular function. We examined the effect of 2‐weeks elevation of retrograde SR on brachial artery endothelial function in young and in older men.Methods and ResultsThirteen healthy young (23±2 years) and 13 older men (61±5 years) were instructed to continuously wear a compression sleeve around the right forearm to chronically (2 weeks) elevate brachial artery retrograde SR in 1 arm. We assessed SR, diameter, and flow‐mediated dilation in both the sleeve and contralateral control arms at baseline and after 30 minutes and 2 weeks of continuous sleeve application. The sleeve intervention increased retrograde SR after 30 minutes and 2 weeks in both young and older men (P=0.03 and 0.001, respectively). In young men, brachial artery flow‐mediated dilation % was lower after 30 minutes and 2 weeks (P=0.004), while resting artery diameter was reduced after 2 weeks (P=0.005). The contralateral arm showed no change in retrograde SR or flow‐mediated dilation % (P=0.32 and 0.26, respectively), but a decrease in diameter (P=0.035). In older men, flow‐mediated dilation % and diameter did not change in either arm (all P>0.05).ConclusionsThirty‐minute elevation in retrograde SR in young men caused impaired endothelial function, while 2‐week exposure to elevated levels of retrograde SR was associated with a comparable decrease in endothelial function. Interestingly, these vascular changes were not present in older men, suggesting age‐related vascular changes to elevation in retrograde SR.

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“…Tinken et al reported, in both brachial and popliteal arteries, that a distinct time-course of adaptation occurred, with initial enhancements in function superseded by structural remodeling . Subsequent studies Naylor et al 2011;Birk et al 2012;Hunt et al 2013;Carter et al 2014) have largely endorsed the notion that changes in the regulation of arterial function occur rapidly, within perhaps three or four sessions of exercise (Wang et al 1993;McAllister and Laughlin 1997). The consequent up-regulation of functional pathways can contribute to arterial remodeling, which, once expressed, allows function to return toward baseline levels.…”

Section: Exercise Training and Structure-function Interactionmentioning

confidence: 99%

“…In the studies described above (Tinken et al 2010b;Naylor et al 2011;Birk et al 2012;Carter et al 2014), and some earlier work (Laughlin 1995;Tinken et al 2008), temporal relationships between changes in arterial function and structure were assessed (Fig. 5).…”

Section: Exercise Training and Structure-function Interactionmentioning

confidence: 99%

Effects of Exercise on Vascular Function, Structure, and Health in Humans

Green

Smith

2017

Cold Spring Harb Perspect Med

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120

101

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Physical activity has profound impacts on the vasculature in humans. Acute exercise induces immediate changes in artery function, whereas repeated episodic bouts of exercise induce chronic functional adaptation and, ultimately, structural arterial remodeling. The nature of these changes in function and structure are dependent on the characteristics of the training load and may be modulated by other factors such as exercise-induced inflammation and oxidative stress. The clinical implications of these physiological adaptations are profound. Exercise impacts on the development of atherosclerosis and on the incidence of primary and secondary cardiovascular events, including myocardial infarction and stroke. Exercise also plays a role in the amelioration of other chronic diseases that possess a vascular etiology, including diabetes and dementia. The mechanisms responsible for these effects of exercise on the vasculature are both primary and secondary in nature, in that the benefits conferred by changes in cardiovascular risk factors such as lipid profiles and blood pressure occur in concert with direct effects of arterial shear stress and mechanotransduction. From an evolutionary perspective, exercise is an essential stimulus for the maintenance of vascular health: exercise is vascular medicine.

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Repeated core temperature elevation induces conduit artery adaptation in humans

Cited by 66 publications

References 29 publications

Passive heat therapy improves endothelial function, arterial stiffness and blood pressure in sedentary humans

Passive heat therapy improves endothelial function, arterial stiffness and blood pressure in sedentary humans

Impact of 2‐Weeks Continuous Increase in Retrograde Shear Stress on Brachial Artery Vasomotor Function in Young and Older Men

Effects of Exercise on Vascular Function, Structure, and Health in Humans

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