Swimming: what the research says

There is some evidence that swimming may help fitness, blood pressure and hip or knee joint pain. Many studies were small, and several tested water exercise in general rather than swimming itself.

What it is

Swimming at your own pace in a pool, the sea or a lake. The NHS counts it as vigorous activity, and this page is about your own swimming, not aquatic therapy or hydrotherapy.

What the research says

• Fitness: In 29 controlled studies of regular pool swimming in non-competitive swimmers, heart and lung fitness improved clearly, in healthy adults too. Many of the studies were small. Some evidence it may help · Lahart and Metsios, 2018 · NHS, 2024
• Blood pressure: In 14 trials with 452 healthy adults, regular exercise in water lowered blood pressure (about 8 mmHg systolic and 3 mmHg diastolic). Results varied a lot between trials, and many used water exercise rather than swimming laps. Some evidence it may help · Igarashi and Nogami, 2018
• Hip and knee joint pain: For people with hip or knee osteoarthritis, a Cochrane review of 13 trials (1,190 people) found that exercise in water brought a small, short-term easing of pain and a small gain in everyday function. No serious harms were reported. The trials tested water exercise in general, not swimming itself. Some evidence it may help · Cochrane, 2016
• A longer life: In large population studies, people who swim tend to live longer, for example 28% lower risk of death over the study period in 80,306 British adults. These studies show a link, not proof. Limited evidence · Oja et al., 2017 · Oja et al., 2024

Is it safe?

Cold open water is a shock to the body. In the first minutes it can make you gasp and lose control of your breathing, which can lead to drowning even in strong swimmers. Enter cold water slowly and never swim alone in open water. Leuci et al., 2026

Don't drink alcohol before swimming, and avoid swimming alone. WHO, 2026

If you have not exercised for some time or have a medical condition, talk to your GP before you start. NHS, 2024

Your own practice complements medical care and never replaces it. Please don't stop or change any treatment without talking to your doctor.

Sessions that fit alongside

Sissoo practitioners offer sessions some people combine with swimming, such as massage: Yoga & Movement Therapy · Body Therapies

Checked 12 November 2026. Next check by May 2027. How we rate the evidence.