I'd like to return to gravity and work on a three-dimensional situation.
回到重力上，考虑一个三维问题。
2
Sitting, as opposed to lying down, further decreases blood return from the lower extremities because of the increased work that must be done against gravity.
坐着比躺着更能降低下肢血液循环，因为坐着要增加做功来克服引力。
3
The G-Tox technique makes gravity your ally by aiding venous return to the heart.