PASSIVE heat exposure acutely improves vascular function and exercise capacity in patients with chronic kidney disease (CKD) according to a pilot crossover trial assessing macrovascular and microvascular responses.
Vascular and Microvascular Responses in CKD
In a randomised crossover study, ten patients with stage G2 to G4 CKD were assessed following far infrared sauna exposure and thermoneutral control. Participants were aged 41 ± 4 years, with six females and estimated glomerular filtration rate of 55 ± 7 mL/min/1.73 m2. Macrovascular function was evaluated using flow mediated dilation. Following passive heating, flow mediated dilation was significantly higher compared with control (3.84 ± 0.61 vs 6.68 ± 0.76%; p<0.01). Microvascular function, assessed via blood flow response to passive limb movement, was also improved (area under curve: 179 ± 29 vs 243 ± 23 arbitrary units; p=0.01). These findings suggest acute improvements in vascular function in CKD. All vascular assessments were conducted after a 60-minute recovery period following each intervention.
Exercise Capacity Following CKD Intervention
Exercise performance, assessed using the six-minute walk test, showed clinically meaningful improvements following heat exposure. Distance covered increased from 632 ± 29 yards under control conditions to 670 ± 30 yards after passive heating (p<0.01), indicating enhanced functional capacity in CKD. The improvement suggests potential relevance for interventions targeting exercise intolerance in this population.
Renal Safety and Clinical Implications in CKD
With regard to renal safety, no significant changes were observed in kidney function or urinary biomarkers of acute kidney injury immediately or 24 hours following intervention. These data suggest that acute passive heat exposure does not adversely affect renal physiology in CKD.
Researchers noted that, to their knowledge, this was the first study to investigate the acute renal, vascular and exercise response to a single session of passive heat exposure in patients with CKD. The observed improvements in vascular and exercise outcomes highlight a potential therapeutic avenue for CKD-related cardiovascular disease, although larger studies are required to confirm clinical benefit. This pilot study provides preliminary evidence to support further investigation of CKD interventions using passive heating strategies.
Reference
Chavez DA et al. Acute effects of passive heat exposure on vascular function and exercise capacity in patients with chronic kidney disease. Am J Physiol Heart Circ Physiol. 2026;330(6):H2001-H2013.
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