JENNIFER HUTCHEON is on the verge of running the Manitoba Marathon's half marathon on Sunday for the first time after participating in the relay last year.
There's a steep curve when it comes to ratcheting up the distance, and Hutcheon wants to be prepared for the rigours of a 13.1 mile run, more than double what she ran in 2008.
"You want to walk away from it," says Hutcheon, 22. "You want to be celebrating, you want to continue with your day.
"You don't want to feel like you've abused your body for the past two to three hours."
One element of training that Hutcheon nearly overlooked was proper hydration.
"When you're doing it, you think I'm going to go into the zone, and I'm just going to run," says Hutcheon. "I definitely would have been at risk for hyponatremia."
Hyponatremia occurs when the body is overhydrated, and Dr. Dean Kriellaars of the Sport Medicine Council of Manitoba estimates that about 600 to 700 of the Manitoba Marathon's 5,200 runners will reduce their performance by drinking too much during the race.
"They'll have muscle cramps and weakness. They're going to think they're dehydrated," says Kriellaars. "It's a hidden problem, and that's because a lot of people overhydrate."
Kriellaars says dehydration is the more common problem.
"Both of them reduce performance," says Kriellaars. "If you're dehydrated as low as two to three per cent, you might be 10 to 20 per cent down in your performance."
Two per cent dehydration is about a kilogram of weight loss, or a litre of fluid. At 18 Celsius, the average 70 kg person sweats about 0.79 litres per hour, and 0.89 litres per hour at 28 degrees.
According to sport dietitian Jorie Janzen, runners can adapt to improper hydration but it doesn't lead to peak performance.
"The more you train, your body will adapt," says Janzen. "But once you put the right ingredients into what you want to do, all of a sudden, you're even better."
One adaptation runners should make is to the temperature, which is expected to hit a high of 27 C on Sunday. With the newfound hot weather, runners may not have practised running the recommended four to 10 times in a hot environment. In these cases, Kriellaars suggests that runners slow their pace by about 30 seconds per mile.
"A lot of people say 'I've got to get my time to qualify for Boston,'" says Kriellaars. "But that's on a perfect race day."
Reach the recommended hydration zone
With the Manitoba Marathon coming up on Sunday, here are some tips on staying within the recommended hydration zone on race day:
Leading up to the race, consume two to three litres of fluid per day. This can include water, sport drinks, tea, coffee, soup, and juicy foods like fruit.
On race day, drink 500 to 600 millilitres of fluid with a pinch of salt two hours before the race, and 200 to 300 ml 10 to 20 minutes before. Urinate before the race.
During the race a 50 kilogram person should have a serving of water at two of every three stations while a person weighing 70 kg should have one serving at each station. Have a sport drink serving at every fifth station. A serving is about 100 ml.
After the race drink about 500 ml over a steady period of time and have a salty snack.