In addition to cooling us down, sweating is one of our bodies’ natural means of eliminating toxins. So does this mean the more we sweat, the better we feel? Not necessarily, say most experts. Though fitness instructors may be raising thermostats in exercise classes across America, the latest trend of hot workouts appears to offer more risks than rewards. Warmer environments (say, between 75 and 90 degrees Fahrenheit) can help prevent injury (by increasing blood flow to muscles). But our hearts work in overdrive when we go hard in the heat. Plus, we lose key nutrients through excess sweat and up our chances of dehydration when working out in too-hot temps.

The Takeaway: Unless you want to spend most of the day prepping for and recovering from fluid loss, think twice before heading to that hot workout class.

Make It Happen Like a Greatist: Still curious about a hot workout class? Drink at least 20 ounces of H20 before entering that hot room.

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