Expert: Dr. Gary Mak - Specialist in cardiology and President of the Hong Kong Association of Sports Medicine and Sports Science
- A proper amount of water supplement is important to marathon runners
- Start increasing water supplement 2 days before the race
- On the race day, you should start drinking water about 2 hours before the race. You may also drink a certain amount of water every 20 – 30 minutes depending on the temperature and humidity
- You should also drink water after the race in order to help recovery.
- Water intoxication usually happens to non-professional runners who need more than 4 hours to complete a marathon run and drink too much water during running. The over-consumption of water causes the sodium levels of blood to drop.
- The over-consumption of water can, in severe cases, result in brain edema or heart edema which will eventually cause coma or death.
- Therefore, if your running time is more than 90 minutes, you are recommended to drink some electrolyte beverage to prevent water intoxication. The supplement process should depend on your running duration and body weight.
- As a reference, it is acceptable if you lose 1 kg after race. But if you weigh more after race, that means you have absorbed too much water.