Is running bad for your knees? It’s a common concern, but most evidence suggests that it’s largely beneficial for the joints.

One of the main reasons that people think running is bad for your knees is because of the pressure—or load—it places on the joints. Interestingly, the overall “force exertion(施加)” for walking and running might be equal over similar distances. A small study published in Medicine and Science in Sports and Exercise showed the reason for this. In the study, researchers asked 14 adults to walk or run on a moving platform that recorded data on the amount of force, or load, each step had. Results showed that the force exerted on the knees while running was as much as three times higher than while walking—but this was offset by the time runners spent in the air and the length of their stride(步伐). The overall force exerted on the knees when running or walking over the same distance was fairly similar.

And while the joint impact caused by running has long been a concern, it has never been shown to increase the risk of knee osteoarthritis(膝骨关节炎). In fact, multiple studies have shown that runners are less likely to develop osteoarthritis than non-runners. There are various theories for why this is the case. Some researchers suggested that runner’s lower risk of developing a bad case of osteoarthritis because of their lower BMI. And some found that running positively changed the interior environment of the knee. More research needs to be done here, but it seems that running has a protective, beneficial effect on knee joints, rather than a detrimental one.

Running is free, accessible and easy to do. And it won’t increase your risk of knee problems. You do, however, need to take the right precautions(预防措施), such as always wearing the correct shoes, making a weekly exercise plan, and doing some strength training. 

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1.What can we know about the small study?

A 14 old people took part in it.

B The participants just needed to run.

C It helped us put aside a common concern.

D All participants recorded data by themselves.

解析：选C。C细节理解题。根据第一段的“It’s a common concern”和第二段的“Interestingly, the overall “force exertion(施加)” for walking and running might be equal over similar distances. A small study published in Medicine and Science in Sports and Exercise showed the reason for this.”可知，“跑步对膝盖有害吗？”这是一个大多数人都会关心的问题，人们认为跑步对膝盖不好的主要原因之一是跑步会给关节带来压力或负荷。有趣的是，在相似的距离内，步行和跑步给膝盖带来的总的“压力”相近，所以跑步并没有给关节带来很大损害，而一个小型的研究证明了这一点。故选C。

2.Why non-runners are more likely to get osteoarthritis than runners?

A Due to the more force their knees get.

B Because of non-runners’ higher BMI.

C For the healthier condition of their knees.

D Because they hurt their knees while walking.

解析：选B。B细节理解题。根据第三段的“Some researchers suggested that runner’s lower risk of developing a bad case of osteoarthritis because of their lower BMI.”可知，跑步者患骨关节炎的可能性较不跑步的要小，原因之一是他们更低的体重指数BMI，即不跑步者体重指数往往更高。故选B。

3.What does the underlined word “detrimental” mean?

A Romantic.

B Dynamic.

C Sustainable.

D Damaging.

解析：选D。D词义猜测题。根据划线部分前面的“running has a protective, beneficial effect on knee joints”及“rather than”可知，跑步似乎对膝关节有保护作用，而不是“有害”。故选D。

4.Who may be interested in the passage?

A Technology fans.

B Sports lovers.

C Shoe sellers.

D History researchers.

解析：选B。B推理判断题。本文告诉我们“跑步伤膝盖？”这一经典偏见如何被打破，属于运动方面，因此运动爱好者会感兴趣。故选B。