A marathon runner's sports performance is highly efficient when the runner is adequately hydrated. An excess or deficit of fluids can lead to fatal consequences. Running creates excess heat. This leads to sweating- a coping mechanism of the body to cool down. The blood fluid becomes thicker as a result of the decline in fluid content in the body. Greater force is required to pump blood through the veins. This overloads the heart eventually leading to a heart attack.

"When training for a marathon, runners must drink water at regular intervals. This is to avoid dehydration especially with such variables like warm weather, running intensity, rate of sweating. Dehydration is common, leads to muscle cramps due to fluid and electrolyte loss and so must be avoided," says Dr. Santosh Dora, Senior Cardiologist, Asian Heart Institute.