04/16/2012 01:44 pm ET Updated Apr 16, 2012

Boston Marathon Heat Wave: How Runners Can Stay Cool

The Boston Marathon kicked off this morning, despite concerns about the unseasonably warm weather. With temperatures expected to rise to 84 degrees at a time of year when most participants were expecting something more temperate, many were concerned about problems like heat stroke.

In fact, organizers were so concerned, they offered a deferment to the 27,000 participants, according to an AP report.

"We're asking runners who haven't run previously to think about tomorrow and maybe coming back next year," Boston Mayor Tom Menino told attendees of a pre-race dinner, according to the AP. "We don't want to have any accidents out there, or anybody overtaken by the heat."

Heat stroke occurs when the body temperature rises above 105.1 degrees, according to Dr. Lewis Maharam, a sports medicine specialist and the running columnist for the New York Daily News. Interestingly, he says that the sometimes-fatal condition isn't necessarily associated with an extreme external temperature. Being simply unadjusted to the temperature -- or poorly trained, so that the exertion is too great -- can lead to a medical emergency. He recently wrote:

[I]t doesn't necessarily need to be warm for runners to get heat stroke. When a participant over-reves [sic] their engine and tries to run too fast at too fast a pace, they can raise their body temperature. I have seen heat stroke on a 70 degree day and also on very hot days where the runner was not used to the heat and still pushed to a time too fast for them.

So while we can't control the weather, as summer approaches, marathoners can do their part to train properly and condition themselves for potential heat waves. Here are a few tips:

- Start hydrated: drink enough water so that your urine is a pale yellow color. For more, check out our hydration chart.

- Avoid caffeine: Caffeine can make the body work overtime, according to this Princeton University explainer. Stick with electrolyte-rich drinks that hydrate and replace the salt and other nutrients you're losing as you sweat.

- If you're sick, stay on the sidelines: The Boston Athletic Association co-medical director Pierre d'Hemecourt cautioned participants with recent colds, flus or food poisoning to sit this one out.

- Slow down: A hot day is no time to go for a personal best. Stick to a comfortable pace throughout the marathon so that you're maintaining an exertion rate that your body is used to.

Above all, pay attention to yourself: if you start to feel sick, stop at a medical station to have a professional evaluate you.