Cardiovascular autonomic modulation during passive heating protocols: a systematic review.
Level 1 - systematic review of randomized trials
Systematic review of randomized/controlled physiological trials evaluated with RoB-2
PubMed 36343372 · doi:10.1088/1361-6579/aca0d9
What was done
A systematic review searching MEDLINE, LILACS, EUROPE PMC, and SCOPUS was conducted to evaluate the effects of passive heating protocols on cardiovascular autonomic control in healthy adults. Eligible studies assessed cardiovascular autonomic regulation using spontaneous methods including heart rate variability (HRV), systolic blood pressure variability (SBPV), and baroreflex sensitivity (BRS). Risk of bias was appraised using the Cochrane RoB-2 tool.
What was found
Twenty-seven studies were included in the qualitative synthesis (the abstract reports no pooled numerical effect sizes or total participant count). Whole-body heating protocols reduced cardiac vagal modulation in 14 studies, and 2 studies reported both increased sympathetic modulation and vagal withdrawal. In contrast, local heating protocols and sauna bathing appeared to increase cardiac vagal modulation. Most whole-body heating studies reported reduced BRS, though overall BRS findings remain controversial due to methodological differences in heating protocols and analytical methods.
Why it matters
This review clarifies that cardiovascular autonomic responses differ markedly by thermal modality, with whole-body heat stress inducing vagal withdrawal and sympathetic shift, while local heating and sauna exposure appear to enhance vagal tone.
Limits
The abstract reports only qualitative synthesis with no meta-analytic effect sizes or overall participant sample size. Findings exhibit substantial methodological heterogeneity across heating protocols and baroreflex assessments, and are restricted to healthy adults.
Cited by
- supports Sauna use increases parasympathetic activity, improves heart rate variability, affects blood pressure, and mimics aerobic cardiovascular exercise.