Bone mass changes are site-specific rather than evenly distributed throughout the skeleton with the tendency that weight-bearing bones are more affected than non-weight-bearing bones.
这种变化在骨骼内并非平均分布，而是有部位特异性，承重骨比非承重骨受影响更为严重。
2
Swimming is such a perfect option because it meets all of those requirements and it's non-weightbearing, too!
游泳就是这样一项很好的选择，因为游泳可以满足上述要求，而且不负重。
3
It stimulates the cardio-respiratory system and it's non-weightbearing.