In July 2015, a 30 year old triathlonist died during an Ironman race.
The cause of his death was cerebral oedema caused by hyponatremia.
Since this tragic event, more and more events managers have realized that not only the importance of hydration should be mentioned, but also the dangers of overhydration (sodium loss) should be highlighted.
The following extract is from the Boston Marathon Event Information.
Recognize the symptoms of overhydration such as water wobbling in your stomach, strong persistent headache, swollen hands and feet, queasiness, nausea, discomfort in your stomach, panting.
When experiencing these symptoms, don't drink more until the first urination.
Why is overhydration (hyponatremia) dangerous?
Exercise-associated hyponatremia occurs when the sodium level in the blood drops under 135mmol/litre (normal level is between 135 and 145).
Sodium in sports drinks might delay it, but the excessive consumption of sports drinks might cause overhydration as well. It affects mainly those athletes, who spend more than four hours on the course and drink too much water or sports drinks before, during, and after the race.
Having too much fluid dilutes sodium concentration in the blood.
If kidneys cannot excrete extra fluid properly (that is we can't get rid of the surplus) this state might cause an increase in the water content of the cells, and lead to the swelling of our brain, which is most sensitive to it, the formation of cerebral oedema which might be lethal in very severe cases.
You should always pay attention to taking solid (or gel) refreshment and salt tablets along with proper fluid replenishment during long distance races.
Considering the above mentioned reasons, ENDURAID focuses on maintaining the proper balance of water and sodium beside the energy supply (carbohydrate replenishment) when devising a refreshment plan.