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Runners gearing up for fall races are starting to feel the heat of training during the middle of summer – when their longest runs are scheduled during some of the hottest weeks of the year.

But most experts agree that runners shouldn’t sweat over the thought of building all that extra mileage in steamy weather, claiming that it really just boils down to teaching the body how to adapt to running in the heat and knowing when to tweak a training schedule.

“I think runners should be flexible,” said Roberto Mandje, an Olympic distance runner and head coach for New York Road Runners, host of the TCS NYC Marathon, a 26.2-mile course that snakes through each of the city’s five boroughs in November.

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“Runners should learn to temper their expectations, and not live or die by one training plan.”

By that, Mandje means that runners need to consider extreme weather conditions before each run, and be willing to alter the plan if necessary. For example, if it’s too hot to maintain the recommended pace on a training run – say, 8 minutes per mile for 15 miles – a runner could shorten the distance to 14 miles so as to compensate for losing as much as 30 seconds per mile.

“In the end, you’ve worked just as hard,” said Mandje, adding that runners can practice their race pace during other intervals in their training. “I think it’s more important to focus on effort and time.”

But for those brave enough to push through those hardest miles under the brutal summer sun, it may lead to an added advantage when toeing the start line for a race like the Chicago Marathon in October.

“It’s a question scientists are debating right now, but there is some evidence suggesting that it does make you stronger, training in the heat,” says Alex Hutchinson, a sports science journalist and author of “Endure: Mind, Body, and the Curiously Elastic Limits of Human Performance.”

Research has shown that running in hot weather not only boosts an athlete’s blood plasma – carrying much-needed oxygen to working muscles – but it also teaches the mind to better temper the pain of pounding the pavement for long distances.

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“You just get used to the suffering,” said Hutchinson, an elite runner himself who has conquered races of 1 mile to a marathon. “You get used to dealing with discomfort and it increases your endurance.”

Still, there are safety risks with running in hot and sticky weather, specifically those that concern a runner’s fuel and hydration levels – but that’s not always as simple as just chugging water and sports drinks at every opportunity during a run, according to some experts.

In some extreme cases, overhydration can cause water poisoning, a potentially lethal condition known as hyponatremia.

Some athletes sweat more than others, so it’s important for runners to learn their hydration needs during training. Studies have found that elite runners can sweat up to 2.6 liters an hour – an impossible amount of fluid to replenish during a run of several miles.

It’s important to drink a moderate amount of fluids during a run – or, to a certain extent, even supplement lost electrolytes with sports drinks and salt tablets – but the key is to hydrate as much as possible between runs, Mandje said.

Still, the most important advice to any runner enduring the high temps of summer is to pay attention to your body – and be careful testing the limits.

“We have a remarkable ability to get out there and handle all sorts of conditions,” Hutchinson said. “As long as you’re willing to listen to the feedback your body is giving you.”

This story originally appeared in the New York Post.