04-08-2025
Exercising in the Heat Can Boost Your Fitness.
Tish Hamilton is a veteran of 59 marathons and five ultramarathons. The 63-year-old former executive editor of Runner's World also lives in Savannah, Ga., where training through summer heat and humidity is a given. And while the conditions are unpleasant, she has come to appreciate them, knowing that come fall, she'll perform at her best.
'I don't think I ever get used to it,' Ms. Hamilton said, 'but I know how good it's going to feel once the humidity breaks.'
It's not in her head. Research suggests that exercising in warm, humid conditions can provide what some call 'poor man's' altitude training — improving performance in endurance sports like triathlon, cycling and running.
In the first few weeks of training in hot conditions, your body sends more blood to the skin's surface to create sweat. This leaves less of it for your muscles, which is one reason you often get tired more quickly in early summer.
But your body adjusts by creating more blood, as well as more red blood cells, over four or five weeks, similar to what happens to your body after three weeks at altitude. You may also experience a boost in your VO2 max, the maximum rate at which your body uses oxygen while exercising.
While you won't necessarily feel the benefits during the thick of summer training, you likely will on the first cool days of fall.
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