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Source: From Hydration to Hyperhydration
Thirty years ago, marathons and other physical endurance events were reserved for top athletes. Since prolonged intense physical exertion can cause excessive sweating, the importance of adequate fluid intake to avoid the occurrence of dehydration is emphasized in these endurance athletes.
“In the 1990s, the American College of Sport Medicine recommended that athletes drink as much as possible, and the US military encouraged its soldiers to drink 1.8 liters of water per hour when the temperature exceeded 30 degrees Celsius,” recalls. Dr. Marc Gosselin, an emergency physician specializing in sports medicine and the medical director of Ironman Mont-Tremblant for six years. “At that time, the dangers of overhydration were unknown. We now know that these recommendations can be exaggerated and dangerous: overhydration can lead to hyponatremia, a medical condition that can lead to various physiological disorders, coma and even death.
According to the doctor who lectured on the subject, the American military’s directive resulted in 125 hospitalizations and at least 6 deaths from hyperhydration between 1990 and 1996. Marathon runners also died of hyponatremia: a first in the Valley. Giants Marathon in California in 1993, followed by Kelly Barrett in the Chicago Marathon in 1998 and Cynthia Lucero in Boston in 2002. In 2007, a 22-year-old died of overhydration at the London Marathon.
A study published in 2005 New England Journal of Medicine It has been determined that approximately one-sixth of marathon runners develop some degree of hyponatremia. It would be slow marathon runners, those who sweat little and who drink a lot of water who would be most at risk. Hyponatremia claims victims in other disciplines. For example, three years ago, a young American football player in Georgia died after drinking 15 liters of water and sports drink in a short period of time at the encouragement of his coach who thought he was doing the right thing.
“We put so much emphasis on hydration that we now encourage people to drink as much as possible before, during and after sports. Do you have cramps? My graduation! Fatigue? My graduation! Those who sell sports drinks also pick up on this message. This means that in a short period of time, athletes can drink 4-5-6 liters or more of fluid. It can be very dangerous! “, Dr. Gosselin underlines that every Ironman should treat people who are too drunk and sometimes hospitalize them for several days.
A dangerously low sodium level
The term hyponatremia refers to low levels of sodium in the blood. When we drink too much water in a short period of time, the kidneys don’t have time to excrete water and sodium levels in the blood drop quickly.
“The effect is worse during prolonged physical activity, because the body produces an antidiuretic hormone that causes it to retain more water,” explains Dr. Gosselin. “This is called training-related hyponatremia. “Although in normal times the kidneys can eliminate between 800 and 1000 ml per hour, in marathon conditions, antidiuretic hormone can reduce urine output to 100 ml per hour, can we read in the newspaper? Scientific American. Thus, even with profuse sweating, a person who drinks too much water will have a net gain of water.
Training-related hyponatremia can occur during athletic activity or up to 24 hours after an endurance event. A rapid drop in sodium levels in the blood can cause nausea, malaise, headache, vomiting and, in the most severe cases, convulsions, coma and even respiratory arrest. “You have to treat these people quickly with hypertonic saline, a strong sodium concentration. But the best is prevention,” says Dr. Gosselin.
Drink when thirsty and in moderation
As training-related hyponatremia is now better known, fluid intake recommendations for both high-level athletes and weekend sports enthusiasts have been revised in recent years. For example, the International Marathon Medical Directors Association (IMMDA) recommends that runners aim for a ad-lib Between 400-800 ml of fluid per hour. Higher doses for fast runners competing in hot conditions and smaller doses for slower walkers or runners in cooler conditions.
For his part, Dr. Gosselin invites athletes to trust their thirst. “Unless you have a specific medical condition, thirst is a reliable mechanism to tell us when we should drink or not. He refers to a statement signed by international authorities in 2015, which recommends that athletes follow their thirst.
Also, the IMMDA recommends consuming sports drinks with added electrolytes during events of 10 km or longer or that last longer than 1 hour 30 minutes. Hyponatremia may also occur. »
The sports expert finally recalls the importance of adequate training to acclimate the body to the sporting event, as well as the weather conditions on the day of the event. “Endurance events are stressful on the body and everyone reacts differently. The more you know about your own body, the better you will be able to gauge how much fluid you should be taking in a given situation. »
During a sporting event, it is important to stay well hydrated while avoiding excessive drinking before, during and after the event. Experts recommend drinking between 400 ml and 800 ml of water or, quite simply, depending on how thirsty you are!