It is the thermal shock that is dangerous, not the “digestion cuts”

It is the thermal shock that is dangerous, not the “digestion cuts”

A group of children play in the pool at a summer camp in Villanueva de la Cañada (Madrid).A group of children play in the pool at a summer camp in Villanueva de la Cañada (Madrid).

Every summer, in the hours closest to meals, there are boys and girls by the pool or on the sand, impatiently waiting for something to digest. When this process is complete, they can finally bathe, which can take anywhere from 30 minutes to 2 hours depending on the parent and the abundance of the food. What happens if they dive prematurely? The name of the threat is known: Digestion Cut. If digestion is disrupted, conventional wisdom says you can drown.

This idea of ​​waiting a while after eating before taking a bath is also present in other countries, although the popular explanations do not refer to an interruption in digestion. Some warn that cramping is more likely, so being in the water would be dangerous. Others argue that since almost all of the blood is concentrated on the digestive process, less reaches the muscles of the arms and legs, making swimming difficult.

There is no scientific evidence for either claim. According to a review of the scientific literature on the subject, published in the International Journal of Aquatic Research and Education in 2011, “there are no documented cases where eating before swimming has resulted in or contributed to drowning, whether fatal or nonfatal.” . The text indicated that it could be a myth, but we continue to hear the recommendation.

“It’s a bit of an urban (and rural) legend to call it that because it has little to do with digestion,” says Jesús Sueiro, spokesman for the Galician Association of Family and Community Medicine (AGAMFEC). “It has more to do with thermal shock when you suddenly come into very cold water. There is a circulatory collapse, hypotension or a drop in blood pressure, a kind of syncope. Dizziness can occur, even vomiting, and if you’re in the water at that point, there could be drowning due to unconsciousness,” he explains. By getting in carefully, slowly and gradually and letting the body acclimate, the risk is already eliminated.

meals and exercise

However, the insistence on basing everything on food is not entirely unfounded. Andrés Sánchez Yagüe, Head of the Communications Committee of the Spanish Foundation for the Digestive System (FEAD) and Head of the Endoscopy Service at the QuironSalud Marbella Hospital, explains that in a way digestion stops. “What we commonly know as a gastric cut is a phenomenon medically called hydrocution. In this phenomenon, what happens is that in the face of a sudden temperature change due to skin contact with cold water, digestion stops to redirect blood flow from the digestive tract to the skin. So yes, in the digestive incision, the digestion process stops,” he assures. The danger, he explains, is that “digestion disorders include vomiting, which on a full stomach can trigger passage of the stomach contents to the lungs, which would facilitate drowning.”

The director of the Spanish School of Rescue and First Aid, Alberto García Sanz, points out that they distinguish between two different phenomena. What we popularly call a digestive cut is actually poor digestion, he explains. “After we’ve eaten, the digestive system needs a higher concentration of blood and oxygen, which makes us sleepy, for example, while there are fewer supplies in the brain. When we perform a physical activity, the muscle groups involved in that activity also require oxygen and blood supply, increasing respiratory and cardiovascular rates. To the detriment of what? To the detriment of this digestive activity,” he affirms. Here, however, water has nothing to do with it: any physical activity on a full stomach can cause gastrointestinal discomfort, nausea, vomiting or dizziness. If this happens to us while we’re running, nothing happens; if we swim we can drown.

On the other hand, García Sanz speaks of hydrocution, which is actually a thermodifferential shock. “If we suddenly dive without having taken a shower, there is a temperature change at the moment of contact with the water, a thermodifferential shock. Loss of consciousness can occur and we drown. We couldn’t have eaten,” he clarifies.

The term hydrocution was coined by the French professor G. Lartigue in the 1950s as an analogy to electric shock. It is an execution by water, but there is no scientific consensus on the specific physiological process that causes syncope to occur, although it is suggested that the culprit is temperature change, not digestion.

For prevention, focus on temperature

This phenomenon, which forces us to wait to bathe after eating, is actually a combination of three factors: temperature, physical activity and diet. The former already poses a risk in itself: if we suddenly step into cold water after a long period of sunbathing or exercising, i.e. if we have a high body temperature, the thermal shock is greater and can cause fainting This could also happen to us if we take a cold shower after exercising, but here the greatest danger would be “that if we lose consciousness, we’ll hit ourselves,” explains García Sanz.

The food thing comes into play when you associate it with physical activity. “The general recommendation is not to do physical exercise after eating (this is why athletes eat several hours before a game or competition) or anything that can cause physiological stress, including going into the water suddenly and causing a temperature shock water is cold (below 24ºC it is more or less considered cold),” says Luis Miguel Pascual, research director at That is, if you go into the water right after eating, but there is not much difference in temperature between the water and the body, or you do it gradually and your intention is to just soak there and not do any physical activity, there would be no risk (about the normal in the water).

Expert insists we should stop talking about indigestion because there’s no scientific evidence post-meal bathing is dangerous. What is potentially dangerous is this thermal differential shock and this is where prevention should focus to avoid uninformed risks. “I don’t avoid the risk of staying in the sun for two hours to digest and then abruptly jumping into the water,” said Juan Jesús Hernández, a doctor and technician from the Red Cross health department. Between January 1 and July 31 this year, 222 people died from drowning, according to the Royal Spanish Federation of Rescue and First Aid. The causes are not mentioned, but drowning after thermal differential shock is one of those that we can prevent.

The important message, Hernández stresses, is to get in the water little by little, get wet little by little, and consider if we’re overheating. In swimming pools, always shower beforehand because when we jump in, the temperature change is more abrupt. “In fact, this situation, hydrocutions, is much more common in the pool than on the beach, which I’m increasingly entering,” he says.

Not everyone will go into shock when making this sudden change in temperature, but Luis Miguel Pascual from explains that it is always necessary to take precautions. “If you’re driving a car on a road and a corner unexpectedly catches you too fast, it’s not the same driving a modern car as it is driving an older one, with bad brakes, no ABS… it adds factors risky. The same thing is happening here,” he says.

He adds that it is also very important to monitor children as the main risk factor for them is “failure of adult supervision”. And then everything we already know: “Avoid poorly guarded areas, follow directions, etc.” Also in cases where the person loses consciousness, you don’t see anyone fighting in the water, they just go to the bottom, so the risk is greater when the mouth and nose are submerged, especially if nobody notices and acts quickly. It is much better to do everything possible not to get into this situation.

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