Bone density contributes to the strength of the bones; and their density changes in response to body weight and to weight-bearing exercise.

骨密度代表骨的强度，骨密度依随体重和负重锻炼而相应升降变化。

youdao

I always see some people riding the bicycle to exercise their bodies, they are group and look so fit, I can tell from their body shapes.

我总是看到一些人骑自行车来锻炼他们的身体，他们是一群人，看起来很健美，从他们的体型就可以看出来。

youdao

They can build their body through exercise.

他们可以通过运动来健身。

youdao

He counsels people that the best time to exercise is the one that works with their body clock and fits with their schedules.

FORBES: Best Time To Hit The Gym

One finding so far: How people interpret their body's sensations during and after exercise plays a large role in whether they enjoy it.

WSJ: Hard-Wired to Hate Exercise?