Cold water swimming: is it bad for your heart?

Cold water swimming can improve blood pressure and fat levels in the blood when practised regularly by those in good general health. However, if you have a heart condition, there are risks you should consider and discuss with your doctor or nurse specialist before starting swimming.

Our heart works harder when we’re moving through water than when we’re on land. And the colder the water, the harder the heart must work. Just entering very cold water can lead to a ‘cold shock’, which can cause a faster heart rate, higher blood pressure, and shortness of breath.

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While more research is needed into the effects of cold water on the body, we do know it can lead to hypothermia and raise our stress hormone levels, increasing the risk of abnormal heart rhythms (arrhythmias) and possibly even cardiac arrest.

Guidance from the Association of Chartered Physiotherapists in Cardiac Rehabilitation suggests that water temperatures between 26-33°C (79-91°F) are safest for people with heart conditions. As most sea water around the UK is unlikely to reach these temperatures, swimming in a heated pool is likely to be a safer option.

Although cold water swimming may not be suitable for everyone, that doesn’t mean all swimming is off the table if you have a heart condition. But you should always check with your doctor or nurse specialist about how to exercise safely in water, especially if you are new or returning to swimming.

Tips for swimming safely with a heart condition

You should only swim when you are feeling well and allow at least one hour to pass after a meal before you get in the pool, lake or sea.

When swimming, enter and exit the water gently, preferably at the shallow end, to gradually get used to the change in temperature and depth. As with any exercise, it’s important you warm up and cool down, so start and finish your swim at a slower pace and build up and down gradually.

Avoid swimming on your own by going with a friend or as part of a group. This gives the security of having someone to look out for you during your swim, as well as the additional social benefits of exercising with others.