麻豆影院

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CU-麻豆影院 researchers discover optimal range of slopes for extreme uphill running
Dec. 16, 2015听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听听 Rodger Kram
Racing on foot uphill on steep inclines is never easy, but researchers at CU-麻豆影院 have discovered a range of slope angles that actually erase the advantages of running versus walking while ascending at a constant speed, says Rodger Kram, an associate professor in the Department of Integrative Physiology and a co-author of the study.
CUT 1 鈥淎t these steep angles you can either walk or run because the speeds are pretty slow. And we were curious as to whether it would be better to walk or to run. (:09) And especially in this range of optimal angles walking uses less energy and it would be less tiring than running at that same speed.鈥� (:18)
The study is believed to be the first to examine the metabolic costs of human running and walking on such steep inclines. The research focused on the challenges posed by vertical kilometer races, or VK, which have grown in popularity in recent years in the U.S. and Europe. Athletes must run or walk up steep slopes ranging between 10 degrees and 30 degrees in order to ascend 1,000 meters over a distance of less than 5 kilometers, or about 3.1 miles.
CUT 2 鈥淲e thought that there would be sort of a 鈥楪oldie Locks Angle,鈥� that is there would be an angle where it was best and if you went any steeper then that would be disadvantages. So we thought that there was going to be a single angle. And we though it was going to be about 30 degrees based on these races that are done in Europe. The records tend to be set on about 30 degrees. (:20) But what we found was there鈥檚 kind of a broad plateau of angles - between about 20 degrees and 35 degrees - where it doesn鈥檛 really matter.鈥� (:29)
Researchers also recorded the athletes鈥� strides using high-speed cameras and found that the mechanical differences between running and walking begin to disappear on extreme slopes. Runners on flat ground experience an 鈥渁erial鈥� phase during their stride when both feet are off the ground but runners on steep inclines shorten their stride and make more rapid steps while keeping one foot in contact with the ground at all times.
CUT 3 鈥淩unning involves an aerial phase where you鈥檙e flying through the air. You don鈥檛 have any feet on the ground. But at these steep angles when we ask these people to run they still had at least one foot on the ground. We used high-speed video and recorded the rate that they took steps and from that we could calculate how long their steps were. (:17) When people walked and ran at the same speed on these fairly steep angles they took longer, slower strides when walking then when running. So that鈥檚 how we distinguished walking and running by the rhythm of their steps.鈥� (:30)
To conduct the study Kram says they had to build their own special treadmill 鈥� one that would reach a 45-degree angle. But they found that angels steeper than 30 degrees created special problems for runners and walkers.
CUT 4 鈥淎 typical gymnasium treadmill they only go to about 9 degrees of incline. We made the world鈥檚 steepest treadmill, basically. We went to 45 degrees. We found that people couldn鈥檛 balance when we had the treadmill inclined to 45 degrees. (:14) We also found that people were slipping on the belt if we just used the belt as is. So we had to take this grip tape from skateboards. It鈥檚 basically sandpaper with a sticky backing to it and we attached that to the belt of the treadmill so that people had enough grip at 35, almost 40 degrees.鈥� (:30)
Kram says the next phase of the study will examine how trekking poles effect running and walking uphill. He says they have become very popular with VK racers. The study was recently published in the Journal of Applied Physiology. For more information visit /news/features/cu-boulder-researchers-discover-o....
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