True or false: debunking 10 swimming myths

We’ve all heard that you shouldn’t swim on a full stomach. But is it true? Can you get sunburn under water? Is it dangerous to jump into cold water? We debunk some of the most common swimming-related myths.

Text: Katharina Rilling; photo: Sanitas

In a case of better late than never, summer finally seems to be putting in an appearance this year. As temperatures rise, many people look forward to cooling off by jumping into the pool. It’s as much part of summer as drinking a beer whilst floating in an inflatable or chips at the pool. Myths abound when it comes to summer swimming. Is it really dangerous to jump straight in cold water when you’re hot or to swim on a full stomach? And can you get sunburn under water– or not?

1. Don’t swim on a full stomach.

Yes and no. ”This is probably one of the best-known bathing rules. But it’s not entirely true”, says Philipp Binaghi from the Swiss Lifesaving Society (SLRG). “That’s why this rule was adapted years ago. We now emphasise: Don’t go swimming with a completely full or completely empty stomach. Anyone who’s just eaten wouldn’t think about running a marathon and no one would think about climbing a mountain over 3,000 metres high without breakfast.” A healthy amount of common sense is needed. “After a big meal, you feel sluggish because your body needs the energy for digestion. The brain is then supplied with less blood and the swimmer could become nauseous and dizzy. At worst, you can pass out in the water and drown silently.”Conversely, you should not swim on a completely empty stomach because this can lead to hypoglycaemia and hunger pangs. 

2. Only non-swimmers or poor swimmers can drown.

False! “Even the best trained body can suffer weakness or cramps,” warns Binaghi. That’s why you shouldn’t swim long distances alone. It’s also important to know your own limits: “Am I fit? Is what I am about to do safe and good for me? Does it match my skill set? Good swimmers know their own limitations and will have a good time in the water,” says the SLRG spokesman.Anyone who is planning on swimming should stay away from alcohol or any kind of drugs, because if you’re under the influence, it’s easy to overestimate your abilities. “Another problem is that alcohol expands the blood vessels. When you’re swimming, the blood then cools down fast and travels from the arms and legs into the core of the body as the blood circulates. This increases the risk of circulatory collapse.”

3. Jumping into cold water can cause a heart attack.

In extremely rare cases. “This danger does exist if you jump directly into cold water when you are very hot. But it really is extremely rare,” says Binaghi. “As the veins constrict abruptly, the blood can no longer circulate properly. In the worst case, this leads to cold shock, unconsciousness or even a heart attack.” It is remarkable, however, that this happens mainly to younger people, whose circulation is more agile than that of older people.

One thing is certain: a big difference in temperature is very stressful for the body, and it can react with muscle cramps and circulatory problems. That’s why you should take a cold shower before swimming or at least enter the water slowly, dipping your arms one after the other into the water and then wetting your face and upper body.  

4. The skin is protected against sunburn under the water.

False. In fact, the opposite is true: UV radiation even intensifies under the surface of the water. According to the academic journal Quarks, about 40% of UV radiation still penetrates at a depth of half a metre. So it’s essential that you wear sun cream when you’re swimming.

5. If your lips are blue, get out of the water.

True. “You shouldn’t wait until your lips are blue, because this is usually a sign that you are too cold,” says Binaghi. “This isn’t good for your body regardless of whether you are on land or in water.” Swimmers should then first dry off well and get warm.

Important: Children in particular cool down quickly and often forget time and the feeling of cold when they’re in the water. When children start to shiver, it’s high time they take a longer break from swimming.

6. You can see and hear someone drowning from the side of the pool or on the shore.

False. “People don’t tend to drown the way they do in films: there’s no shouting for help or flailing around. In fact, drowning is a silent death,” says the SLRG. In most cases, anyone drowning isn’t in a position to draw attention to themselves. Since the mouth is below the surface of the water when drowning and only emerges from the water for a brief moment, the time for exhaling, inhaling and calling for help is too short. This is because the respiratory system automatically focuses on ensuring we can breathe first before enabling speech. 

Waving is also often not possible, because the arms are instinctively stretched out to the side and pressed down on the water surface. This protective function is designed to keep the body above the surface of the water. Drowning victims can’t consciously control their arms. Binaghi emphasises: “The body is upright in the water. Someone drowning can normally only keep their head above the water for 20 to 60 seconds before they go under, which means the lifeguard doesn’t have much time.”

But, of course, a person who is shouting and waving for help may also be in serious trouble. “People experiencing difficulties in the water like this are not in immediate danger of drowning and can participate in their own rescue and reach for lifelines or life rings.”

7. Don’t worry: it’s most dangerous in the sea.

False! “The danger basically depends on the person and how they behave in and around the water. There are environmental conditions, including the type of body of water you’re in, that can have an impact on the risk potential. But ultimately, each person is responsible for their own personal risk management”, explains Binaghi. In other words: there are dangers in bodies of water, but the level of risk depends on how you handle them.”

In Switzerland, most drownings happen in lakes (2019: 24), closely followed by rivers (2019: 23). In comparison, relatively few people drown in outdoor pools (2019: 1).

8. Wet swimwear causes bladder infections

True. Summer is a great breeding ground for bacteria. If you spend a long time shivering in wet swimwear or sitting on the cold stone tiles at the edge of the pool, you can catch an unpleasant bladder infection. When the abdomen cools down, the blood vessels constrict and the blood flow to the mucous membranes is reduced. This increases the risk of infection. That’s why you should always change into dry clothes after swimming.

9. If you swallow water from the pool, you’ll get diarrhoea. 

Sort of. At an outdoor pool yesterday and in bed with diarrhoea today? Although filter systems and chemicals such as chlorine help keep germs in check and the water quality is strictly monitored, there is always a risk of infection. As a result, visitors to an outdoor pool may get an upset stomach or an ear or eye infection. The risk is higher when the water is shallow and warm, such as on the lakeshore or in a paddling pool. So you should try and keep children and babies from swallowing water.

10. You shouldn’t go swimming if you’re pregnant.

False. Swimming during pregnancy is refreshing, keeps you fit and is kind on the body, which makes it perfect for mums-to-be, particularly in the later months of pregnancy when mobility decreases and weight increases. It is important that expectant mums don’t exert themselves too much. For reasons of hygiene, they should stay away from the jacuzzi as the water is often not changed for a long time. Women are susceptible to vaginal infections during pregnancy due to their hormonal changes.