As summer temperatures rise, unless our shoes are laced by 7am, our outdoor workouts get the boot. But for those who can’t bear the thought of trading the running trail for the treadmill, here’s some good news: A new study has determined how to optimize your workout stamina in spite of sweltering heat. The key is pre-cooling.

According to researchers, runners who draped cold towels around their necks, dipped their arms into cold water, slurped on slushies and wore cooling vests and (get this) frozen underwear 20 minutes pre-workout had a slower increase in body temperature over the course of their run. This, in turn, helped them run faster.

For the study, scientists tested 12 men who ran for 30 minutes on a treadmill on three separate occasions, gathering information on the participants’ core and skin temperatures, heart rates and blood lactate levels.

Before the first test, the men sat in a heated lab, sipping a room-temperature sweetened beverage for 20 minutes prior to running.

On the second test, the participants drank 16 ounces of a slushy 20 minutes before their run, which significantly lowered their core temperatures. (The researchers used slushies because sugar mixed with ice lowers the temperature of the resulting beverage more than if it were shaved ice alone.)

For the final test, the participants draped cold, wet towels around their necks, placed one arm into cold water, wore a frozen cooling vest and put on underwear with frozen ice packs attached at the thighs. This was done 20 minutes prior to their run as well. Unsurprisingly, the skin temperatures of the 12 men dropped considerably.

The results showed that the men could sustain a higher relative intensity during the early part of their run after drinking the slushie or cooling their skin. However, by the end of each run, the participants’ core and skin temperatures were nearly identical showing that the pre-workout cooling was short-lived.

 “If you can make people feel cooler, they generally run faster,” said lead researcher Carl A. James, a doctoral candidate at the University of Brighton. The researchers suggest that if you want to have the cooling effects linger for a longer period of time try icing your skin instead of your stomach.

If you’re an outdoors fitness enthusiast, will you give this pre-cooling experiment a try this summer? Which method will you test out—cold towels, frozen underwear or all of the above? Sound off in the comments below.



The New York Times: Slushies vs. Frozen Underwear for Hot-Weather Workouts