Vascular Function after Sauna Bathing in Healthy Older Adults

Abstract

Repeated heat exposure by immersion in warm water improves vascular function in healthy young adults. This observation could explain the health benefits of sauna bathing reported in population‐based studies, in which regular sauna sessions lasting more than 19 minutes were shown to significantly decrease the risk of cardiovascular mortality. However, it is unknown if such sauna durations improve vascular function in older adults. The purpose of this study was to determine if 20 min of sauna bathing acutely improves vascular function in healthy older adults.Six older adults (4 women) without cardiovascular disease and risk factors (age range: 57–71 yrs) underwent a sauna bathing session consisting of 2 bouts of 10 min in a dry Finnish sauna (80°C) separated by 10 min of seated rest outside the sauna. Prior to and following sauna bathing, flow‐mediated dilation (FMD) of the brachial artery in response to reactive hyperemia induced by 5 min of forearm ischemia was assessed by Doppler ultrasound after a minimum of 30 min rest in the supine position in a quiet and thermoneutral environment. The percent change in artery diameter from baseline to peak was used as an index of macrovascular function, whereas post‐occlusive reactive hyperemia (PORH), estimated by the brachial artery flow area‐under‐the‐curve above baseline during the 3 min following ischemia, was used to evaluate microvascular function. Heart rate (HR), mean arterial pressure (MAP), oral temperature (Toral) and mean skin temperature (Tsk) were monitored throughout the study.Sauna caused an increase in HR (55 ± 8 to 86 ± 10 bpm, P<0.01), mean Tsk (33.0 ± 0.5 to 40.7 ± 0.7°C, P<0.01) and Toral (36.7 ± 0.3 to 37.4 ± 0.2°C, P=0.025) while changes in MAP were not statistically different (100 ± 8 to 90 ± 4 mmHg, p=0.137). At the time of FMD assessment, HR (53 ± 5 and 52 ± 5 bpm, P=0.56), MAP (92 ± 6 and 90 ± 5 mmHg, P=0.59) and Toral (36.8 ± 0.3 and 36.9 ± 0.1 °C, P=0.27) were similar before and after sauna bathing, whereas mean Tsk was elevated prior to the post‐sauna FMD assessment (34.3 ± 0.4 vs. 32.9 ± 0.5°C, P<0.01). FMD was similar before and after sauna bathing (4.79 ± 2.21% vs. 4.86 ± 2.73%, P=0.93). PORH was also similar before and after sauna bathing (286 ± 198 vs. 380 ± 168 ml, P=0.18).These preliminary results indicate that macro‐ and microvascular functions are unaffected by two 10 min bouts of sauna bathing at 80°C in healthy older adults.Support or Funding InformationFunded by Fondation de l'Institut de cardiologie de Montréal and by Fonds de Recherche du Québec – Santé.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.