“Drinking lots of water increases blood plasma which, in turn, decreases the blood’s salt content. If you are consuming a lot of water and also sweating, you can easily lose lots of salt. Consequently, your body will lose the electrolytes that are necessary to keep its brain, heart, and muscles functioning properly,” says Dr S.K. Aggarwal, internal medicine, Indraprastha Apollo Hospitals. Symptoms of hyponatremia include nausea, vomiting, muscle weakness, headaches, and bloating in the face and hands.

Hyponatremia is more common among women athletes than men and was also responsible for the death of a 43-year-old woman who was running in a marathon in the United States a few years ago.
Cases of hyponatremia have been on the rise for the past five years due to the popularity of marathons. “Earlier, only athletes would participate in them. Now, most people who take part are not as competitive and they stop a lot of times to consume water. The more they stop, the more they drink, not realising that what they are doing could be harmful,” says Dr Aggarwal.

“While the average person should drink 400 ml of liquid during a regular exercise routine and 800 ml for competitive exercise (running or intense weight training), gentle exercises (such as a brisk walk) need a lot less,” says fitness expert Leena Mogre.
For professional athletes, however, the amount of water to be consumed is a lot more. They can find out how much water their body requires by weighing themselves before and after a workout. “During extremely intense workouts, it is possible for our bodies to lose half a pound or one. For every pound you lose, you should have 1,500 ml of water,” says Mogre.