【听力原文】
From VOA Learning English, this is the Health & Lifestyle report.
Today's program is for people who like to run.
Cold weather during winter months may keep many people from leaving home and running in the open air.
However, a new study shows that the drop in temperature is a good reason to run. In fact, researchers say, running in cold weather helps improve one's performance.
Many people say running in the winter can be difficult. Two reasons are the low temperatures and bitter winds. Yet many runners might find it easier than running in hot weather.
That could be because lower temperatures reduce stress on the body. When you run in cold weather, your heart rate and the body's dehydration levels are lower than in warmer conditions. The body needs less water on a cold day than in warm weather.
This information comes from sports scientists at St. Mary's University in London. John Brewer is a professor of applied sport science at St. Mary's.
For this study, he and other researchers put a group of people into a room they called an "environmental chamber." The researchers then recreated summer and winter weather conditions in the room. The test subjects were asked to run 10,000 meters under both conditions. Brewer says he and his team recorded biological measurements of the runners.
"We've got a group of subjects into the environmental chamber, we've changed the conditions to replicate the summer or winter and we've got them to run a 10k under both of those conditions and taken various measurements on each runner whilst they've been completing their 10k."
Brewer says every movement runners make produces heat. He explains that one way in which we lose heat is by sweating. The body loses heat through droplets of sweat. He says the body also loses heat by transporting the blood to the surface of the skin.
"That heat builds up in the body and can be really damaging unless you can lose that heat. One of the mechanisms by which we lose heat is through sweating, but we also lose heat by transporting the blood to the surface of the skin where it can lose heat out into the external environment. Now, that puts more strain on the heart, particularly in hot conditions because it's much harder to lose heat when the external environment is warm as well."
And that increased strain, adds Brewer, can be considerable. Running in higher temperatures results in faster heart rates.
"We found, for example, that heart rates were about 6 percent higher in the hotter conditions. We found that the runners dehydrated by around 30, 38 percent more in those hotter conditions. And they found it about 30 percent easier -- the test of theirthermal regulation, how they felt, (and) their perception of heat -- was around a third lower when they were running in cold conditions."
The body does not have to work as hard to pump blood to the skin's surface. Brewer says that means running in cooler temperatures requires less energy. He adds that serious runners could cut valuable seconds off their personal best times by choosing to run in the winter.
"If you look at top-level sports, if you look at the likes of Mo Farah running 10Ks and winning world and Olympic championships; the difference between success and failure is seconds, and it's certainly not minutes. We can be very confident that in cooler conditions you can certainly slice a decent percentage of time off your personal best."
Several websites note that the most important thing for people who run in cold conditions is to wear the right clothing. Keeping as dry as possible is most important when exercising in low temperatures. Wear mittens on your hands instead of gloves. Wear shoes that will keep you from falling. And especially, wear more than one layer of clothing to keep sweat away from your skin.
So, if you are a runner, don't let winter weather keep you indoors. Simply get ready for the low temperatures and start running.
I'm Anna Matteo.
Faiza Elmasry reported this story for VOA News. Anna Matteo adapted it for Learning English. George Grow was the editor.
Test your understanding by taking this listening quiz. Play each video clip and then choose the best answer.
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Words in This Story
bitter – ad. intensely unpleasant especially in coldness or rawness
replicate – v. to repeat or copy (something) exactly
10K – n. a long-distance road running competition over a distance of ten kilometers (6.2 miles)
chamber – n. a room used for a special purpose
mechanism – n. a process or system that is used to produce a particular result
strain – n. an injury to a body part or muscle that is caused by too much tension, effort, or use
dehydration – n. to lose too much water
stress – n. physical force or pressure
