Eaten, hydrated, slept: the questions to ask yourself before a swim

Before you think about the water, think about yourself. Four quick questions: when you last ate, when you last had a drink, how you slept and how stressed you feel. They take seconds to answer honestly.

When did you last eat?

You may have heard that you should wait an hour after eating before you swim. Current evidence doesn't support that. The American Red Cross's scientific advisory council looked at the question and concluded that swimming within an hour of eating doesn't increase the risk of drowning. It reported minimal side effects at different intervals after a meal, and noted that no major medical or safety organisation currently recommends waiting. The NHS list of what causes leg cramps doesn't mention food at all, and none of the UK safety pages we checked for this guide set a waiting time either.

Treat the hour as a comfort preference, not a safety rule. If you like a gap after a big meal, keep it.

What does matter is not going in on an empty stomach. Northern Ireland's government advice on eating and exercise suggests a high-energy snack, such as a banana or some dried fruit, before a long session, and diluted fruit juice, squash or a sports drink if you can't face food.

When did you last have a drink?

The Northern Ireland guidance says to drink plenty before you start exercising rather than waiting until you feel thirsty, and that what you drink for exercise comes on top of the usual 1.2 litres, or six to eight glasses, you need each day anyway.

The NHS lists the signs of dehydration as including thirst, a headache, feeling dizzy or light-headed, and feeling tired. It also names not drinking enough as one of the causes of leg cramps. If cramp is your worry, the NHS points at fluids rather than food. Water or diluted sugar-free squash are good choices.

"A drink" here means water, not a pint. The NHS lists drinking too much alcohol among the causes of dehydration, and RLSS UK says alcohol and drugs reduce awareness, impair judgement and increase risk.

Did you sleep well?

Sleep shapes how you handle stress and make decisions, and cold water adds extra pressure on top (more on that in cold water shock).

The NHS's signs that you're not getting enough sleep include feeling very tired, irritable or sleepy during the day, and finding it hard to focus or cope with everyday tasks. Focus is exactly what you're relying on when you decide how far to go and when to turn back.

The NHS also says a few nights of bad sleep are usually nothing to worry about. After one rough night, keep the swim short, stay close to your way out, and get out earlier than you'd planned if you're not feeling it.

The Outdoor Swimming Society adds another angle. It lists being tired, along with hangovers, stress and being recently ill, among the things that can lower your resilience to illness picked up from the water.

Are you feeling particularly stressed?

If you are, take care. Stress can leave you feeling tired or colder than normal, so keep an eye on how you feel. It also gets in the way of good decisions. The NHS describes the same thing: stress can leave you struggling to make decisions, with racing thoughts or a sense of being overwhelmed.

You don't have to stay at home. Make it a short dip to take in what's around you, and leave fitness swimming for somewhere more controlled, like a pool. If the swim is how you unwind, let it be a gentle one. And if your breathing starts to run away from you in the water, learn the technique in panic in the water before you need it.

Adding it up

Twelve hours without food or drink is a reason not to swim on its own. The rest add up. A long gap since your last meal, a bad night and a stressful week are three reasons for caution between them, before you've even looked at the water.

Wild doesn't score you. The spot page shows the conditions, and this part is yours. Ask yourself the four questions before you get changed, answer honestly, and let the answers shape the swim: shorter, closer to the edge, or another day.

Then check your bag against the open water kit list, and read Before you get in: the swimmer check for the rest of the check, including the rule that sits over everything: if in doubt, get out.

Sources

1. American Red Cross, Should You Eat Right Before Swimming?
2. NHS, Leg cramps
3. nidirect (Northern Ireland government), Eating well and keeping active
4. NHS, Dehydration
5. London Fire Brigade, Think before you drink
6. Royal Life Saving Society UK, RLSS UK's Don't Drink and Drown campaign
7. NHS Every Mind Matters, Sleep problems
8. NHS Every Mind Matters, Stress
9. Outdoor Swimming Society, 10 WAYS TO STAY WELL SWIMMING

This guide is general information, not a substitute for local knowledge or training. Conditions change: check them on the day, and if in doubt, don't go in. Images on the blog are illustrations, not pictures of specific spots.