Hydration and proper nutrition are key to success when doing a long run like the 10km Sun Run, which takes place this weekend.

That's why new research is being done to see what runners are more at risk for health issues.

Ron Porter is about to run his 10th marathon.

"It's really about the challenge. To go out and improve myself and improve my times."

But before this event, he and hundreds of other runners are giving their vital signs and a few drops of blood to researchers.

Dr. Michael Mohseni and his team at the Mayo Clinic are analyzing runners' blood samples to find out how hydration affects sodium levels and kidney function.

"We want to see what kind of hydration strategy they're using. And then looking at what adverse outcomes they might encounter after running the race," he says.

Sodium is an electrolyte. It works with other substances to stabilize cell membranes and keep your muscles functioning properly.

If your sodium level drops too low from drinking too much water or excessive sweating you can develop what's called hyponatremia.

Symptoms include nausea, vomiting, seizures and in severe cases death.

Runners may also develop a decrease in kidney function from dehydration.

Dr Mohseni's research will reveal which runners may be more prone to developing these problems

And with this information more recommendations can be made on how runners should prepare.

It's similar research done on sports drinks that showed runners who drink liquid fortified with electrolytes and energy do better than runners who drink water alone.

Research that will help runners stay healthy and hopefully improve their performance.

A good rule of thumb when it comes to a run and hydration is:

Drink one cup of fluids prior to activity

1/2 to 1 cup every 15 minutes during activity

2 cups after activity

Try sports drinks with a 6 to 8 per cent carbohydrate concentration -- these include drinks like Gatorade or Powerade.

You definitely want a good meal the night before to build up your energy, something with lots of veggies, grains and lean protein like chicken and vegetables over whole wheat pasta. Then -- Sunday morning before the run -- you'll want a low-fat, mostly carbohydrate meal with a bit of protein for endurance -- something like a fruit and yogurt smoothie if you don't have much time.

If you've got the luxury of a couple of hours aim for a 1/2 bagel with banana and peanut butter or whole wheat toast and eggs with a piece of fruit.