Have a friend flex your foot, bending it down toward your knee.

让一个朋友对着你的膝盖弯曲你的脚。

youdao

The unshod runners' style causes more flex in the foot's springlike arch ankle and knee and engages more foot and calf muscles blunting the impact on the body and making for a more comfortable "ride."

赤足的姿势引起了足部海面拱体、踝骨和膝盖更大的弯曲，更多地利用了足部和腿肚上的肌肉的力量，从而减弱了冲击对人体产生的影响，使人跑起来更舒服些。

youdao

If you are on the correct spot, a muscle should flex as you move your foot up and down.

如果你在正确的地点后，肌肉要当你沿着弯曲你的脚向上和向下。

youdao

Ossur, an Icelandic orthopedics company, which supplies South African athlete Oscar Pistorius with his carbon fiber running blades -- called the Flex Foot Cheetah -- is one of the leading innovators in hi-tech lower-limb devices.

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It was on a new track in the northeastern corner of Italy that the double-amputee from South Africa trained last year for his Olympic debut, running lap after lap on his Cheetah Flex-Foot blades in preparation for his trip to the world's biggest sporting event.

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Shoes should flex where your foot bends, said Noreen Oswell, a podiatrist at The Foot Center at the Cedars-Sinai Medical Towers in Los Angeles.

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