Should you wait an hour after eating before swimming?

Tuesday, November 17, 2009

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It's long been a classic old wives' tale that you can't go swimming directly after you've eaten. But is this true?

Reporter Michael Slater and some volunteers will help find out what happens when swimming and eating are combined.

What's the basis behind not going swimming within an hour of eating? Sports nutritionist Dr Helen O'Connor believes it comes from the fear of getting a stitch or cramp and that if you've got a stitch when you're swimming you might drown.

The theory goes that after a meal, there's an increased blood flow to the stomach and intestines to absorb nutrients. This means there's less blood to deliver oxygen and to remove waste products from exercising muscles.
Dr Helen adds that "there's a bit of competition going on there between the blood and oxygen wanting to go to your stomach to be digested versus your exercising muscle during exercise."

However, there is disagreement to this view. Retired marathon swimmer Susie Maroney believes the whole swimming after eating theory isn't true.

"I think it doesn't matter if you're fit or unfit, you can still have a hamburger and go for a swim — it won't hurt you!" she says.

Susie holds the world record for swimming without flippers for 200km from Mexico to Cuba in just 39 hours.

"During those swims, I got really seasick so Mum made sure I had my favourite little cupcakes while I was swimming ... I had to have nice food as well," says Susie.

So Susie says to not worry about it, while the nutritionist thinks you shouldn't eat and swim. But who's right?

Let's put it to the test.

Michael invites six volunteers of different shapes, ages and fitness levels over for a swim, and of course, lunch. They'll be closely watched by lifeguard Will to ensure that everyone's doing okay in the water.

Before hitting the pool, everyone tucks into lunch:

Angela, Kelly, Simon and Louise are going light on cereal, skim milk and fruit.

While the big eaters wolfing down burgers, chips and milkshakes are Chris, Hugh, Aimee and Michael.

  • Kelly: "I think we're going to be fine with the fruit and cereal, the healthy stuff. But I think the other guys might have a bit of a problem."
  • Hugh: "I used to competitively swim and I used to eat before I went training and people used to laugh at me and go, you'll be sick. I never got sick so…"

After lunch it's time to jump into the pool and get swimming for the next hour.

During their pool time they won't just be taking it easy and will participate in some pool racing and games.

At the end of the hour we'll be able to see if anyone experienced any cramps, stitches or ill feeling along the way.

At 45 minutes into the test, no one has flaked yet, so when the hour is up it appears that everyone has passed the test ... or have they?

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An hour later

Aimee took the burger and fries option. "I feel pretty good but I'm a bit full. My belly's a bit not so good." She kept swimming but felt it was against her better judgement.

Aimee isn't the only one who swam against their judgement.

Kelly ate the healthy food but is having some trouble. "I ate a fair bit of the healthy stuff. The fruit wasn't too bad, but the cereal, I think the milk's made me a bit bloated."

So one of the healthy eaters has gone down with a stomach cramp.

All in all three of the participants were feeling pretty uncomfortable in the pool.

There are a couple of other doctors who share Dr O'Connor's view, that swimming after eating is not a good idea.

Doctors Darren Morton and Robin Callister have extensively studied exercise-related transient abdominal pain (ETAP) — more commonly known as stitches.

"If I was personally going to go for a run or swim or any kind of exercise, I would be steering away from the burgers and chips," says Dr Morton.

Dr Callister adds that you are most likely to get a stitch if you've consumed food or drink fairly shortly before you exercise. So it's not how much you eat, but what you eat that can determine your chance of getting a stitch.

"The composition of the food or drink has an impact on the rate at which it empties out of the stomach, so carbohydrates are typically emptied faster than fats or proteins," says Dr Callister.

Carbohydrates typically pass through your stomach in under an hour, while proteins and fats take up to four hours. Susie Maroney obviously had to eat during her marathon swims, but she mainly limited her intake to easily digestible foods like bananas and baby foods.

To eat, or not to eat?

So eating just before swimming can possibly increase our chances of experiencing exercise-related temporary abdominal pain. But there are some people who deliberately eat prior to swimming, or eat during swimming (such as Susie Maroney).

Therefore, this myth really comes down to common-sense about how fit you are, what you eat and what kind of swimming you'll be doing.

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