Heat thermotherapy to improve cardiovascular function and cardiometabolic health: A systematic review and meta‐analysis

Heat thermotherapy (HT) is reported to promote cardiovascular (CV) and cardiometabolic health benefits. This systematic review and meta‐analysis (CRD42020193669) empirically investigated the efficacy of HT in improving CV and cardiometabolic parameters by assessing responses to single versus multiple HT bouts. Databases (EMBASE, MEDLINE, and Web of Science) were searched up to January 2025 for HT studies investigating CV and cardiometabolic parameters. Inclusion criteria were adults aged ≥18 years, a passive heating stimulus with no exercise involved, and a control group comparison. Fifty‐one papers were included in the meta‐analysis, and publications were separated into HT single‐bout (1 heating bout) and HT multiple bouts (>1 heating bout). After removing outliers, HT reduced diastolic blood pressure in single (n = 20, −2 mmHg [−4, 0], I² = 76%) and multiple bouts (n = 9, −3 mmHg [−6, −1], I2 = 56%) in comparison to control conditions. Mean arterial pressure was reduced in single (n = 22, −5 mmHg [−8, −3], I² = 63%) and multiple bouts (n = 6, −4 mmHg [−6, −2], I² = 49%). Systolic blood pressure was reduced in multiple bouts (n = 8, −5 mmHg [−9, −1], I² = 73%), whereas only single bouts improved flow‐mediated dilation (n = 11, 0.31 g [0.06, 0.56], I² = 0%), and total peripheral artery shear rate (n = 11, 4.09 g [2.87, 5.30], I² = 71%; all P < 0.05). C‐reactive protein, heat shock proteins and arterial stiffness did not change after single or multiple bouts (all P > 0.053). This meta‐analysis found HT improved some acute and chronic CV parameters, with the magnitude of improvement largely unaffected by an individual's health status or HT intervention duration.