Austrian Study Finds Cold Water Immersion Blunts Post‑Exercise Blood Pressure Drop

A six‑week high‑intensity interval training (HIIT) program involving 12 physically active volunteers was split between a cold‑water immersion (CWI) group and a control group. The CWI protocol—one hour at 25 °C after each HIIT session—significantly reduced the post‑exercise hypotension (PEH) response, resulting in a higher mean arterial pressure compared with controls (p = 0.003). Despite this acute difference, neither group showed significant changes after six weeks in plasma volume, blood volume, total hemoglobin mass, or red‑cell volume. Both groups nonetheless improved peak power output. A positive correlation was observed between the magnitude of PEH and plasma‑volume changes, but PEH did not drive long‑term erythropoietic adaptations.