Hot water cardiac rehabilitation

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Cardiac rehabilitation (CR) is a medically supervised programme of exercise, education, support, and counselling for people recovering from major heart problems such as heart attack, heart surgery, or heart failure. It aims to reduce the risk of further heart problems and improve overall quality of life. However, only around 50% of patients eligible for CR access it, meaning thousands miss out on its potential benefits due to issues such as cost, travel distance, or physical limitations. Furthermore, roughly 20% of CR participants drop out before completing the programme, meaning many don’t benefit from referral, and remain at-risk of heart problems reoccurring. Hypertension, or high blood pressure, is one of the main factors that increases the chance of heart problems occurring. When blood pressure is high, the heart has to work harder to pump blood, which increases the risk of future complications. For CR to be effective, high blood pressure needs to be well controlled. Hot water immersion (HWI), which involves soaking in warm water for a prolonged period, may be an alternative way of reducing blood pressure and supporting heart health in people with high blood pressure. Research has shown that sitting in lukewarm water (around 36.5°C) for 40 minutes can lower blood pressure, and using warmer water (around 40°C) may offer even greater benefits. Unlike exercise, which can reduce blood pressure over time but can sometimes place extra strain on the heart during the exercise, HWI may provide these benefits more comfortably and safely for people with high blood pressure.

To investigate whether HWI could form part of a CR programme for people with hypertension, Dr Lucas and her team at the University of Birmingham will first assess the safety and effectiveness of different water depths and temperatures on blood flow, heart function, and blood pressure in individuals with hypertension. Once the optimal depth and temperature have been identified, the HWI therapy will be compared with different types of exercise to determine whether it can produce similar benefits. Following this, the HWI will be built into a CR programme and compared to a traditional programme to determine the long-term benefits of adding HWI to CR. It is hoped that this research will provide insight into how HWI can be safely added to CR treatment, giving people with high blood pressure a potentially safer and more comfortable option to support their heart health during recovery.