Concerned parents subject their children to a steady barrage of health warnings, but none are so frequently repeated - or as dire - as those concerning swimming soon after eating. It goes something like this; if you're foolish enough to take a dip within an hour of your last meal, you'll be seized with cramps that will leave you unable to move and condemned to an early, watery grave. Surely there's some medical truth in a belief that's persisted for so long? Advocates of the swimming-plus-food-equals-quick-death theory have what sounds like a scientific explanation to back it up. After a meal, the body automatically boosts the flow of blood to the stomach and intestines to aid digestion and the absorption of nutrients. But when other muscles are being exercised - as they would be when someone's trying to stay afloat - blood is diverted to these muscles, leaving the digestive system deprived of oxygen and the stomach vulnerable to severe cramps that could make it tough for a swimmer to keep his or her head above water. This isn't an entirely outlandish scenario - plenty of doctors, and the water safety experts at the Red Cross, have stated that a half-digested meal 'could make [swimmers] more susceptible to cramping and exhaustion'. But an equal number of medical experts beg to differ. As early as 1961, expert physiologists such as Arthur Steinhaus were calling the cramping theory 'questionable'. More recently, Richard Fedorak, the head of gastroenterology - that is, the science of the digestive system and its disorders - at Canada's University of Alberta Hospital, dismissed the link between eating and drowning as a 'myth', noting our bodies contain more than enough oxygen to keep our stomachs and plenty of other muscles happy at any given time. Other aspects of the old belief are even more problematic. Even if a swimmer's unfortunate enough to be struck with a bout of cramp, there's little chance this would result in a fatality - most cramps quickly pass or can be eased by deep breathing or stretching the affected muscle, something most swimmers would do instinctively. Snopes.com, a website devoted to the debunking of old wives' tales, points out there hasn't been a single recorded case of a swimmer drowning (or coming close to doing so) as a result of eating before swimming. The other debatable part of the parental warning is the timing - one hour seems to be the standard amount of time diners are supposed to wait before taking a dip, but variations on the story put the danger zone anywhere from 30 minutes to three hours. According to the Red Cross, there's no set period swimmers should wait as the amount of time it takes to properly digest a meal is a highly 'individual variable' that depends on factors such as a person's height, weight and metabolism. So it seems that when it comes to swimming on a full stomach, mum and dad really don't know best. If there's anything parents should warn their children of before a dip, it's alcohol - the American Academy of Pediatrics cites a study that indicates booze is a factor in more than 40 per cent of drowning deaths.