Dr Dhirendra Singhania, director of interventional cardiology at Yashoda Medicity, warned that cold plunges cause blood vessels to constrict, sharply increasing blood pressure and heart stress.
Conversely, sauna heat causes blood vessels to dilate and heart rates to accelerate, which can lead to dehydration through sweating if adequate hydration is not maintained.
The cardiologist advised caution when transitioning rapidly between extreme heat and cold, noting that people with existing heart conditions should consult doctors and stop immediately if warning signs appear.