Gravity has always been defined as continuous force acting down on your muscles, joint and connective tissues, and it has never acted up even for a second. Sometimes it increases at certain positions you make, like lifting heavy objects or sitting down, affecting your spell, which might make this force be 2 or 3 times more than normal.
That makes sense when any adult human tries to measure his height at the morning to find it for example 65 inches, while if he tried to measure it again by the end of the day, he'll find it 64 inches, and the next morning he tries to measure his height again he'll find it 65 again as normal, this is a clear evidence that adults height in the morning decrees by 0.75-1 inches than at night, that happens because their spines have been compressed all through the day due to the gravitational compression that affects their spines, also affecting knees & hips. Moving forward we find that the number of inches lost becomes about 2 inches when people get much older.
Actually losing an inch or gaining it is not an important thing to care about for a lot of people, but this change actually means a lot, because it explains the reason of having all the pains at the end of your day, it's because of the gravitational compressions done on your neck, back, spine and joints. That was the beginning of thinking to have a special kind of treatment using gravity as the main role player in this process.
Inversion therapy is a way of treatment for back pains, simply by hanging upside down or with a certain angle, or make some downward yoga poses, making your body in a reversed position to gravity compared to normal, it actually not only removes pains, but also it helps blood to flow easily and improvements posture, these are some of the outnumbered benefits that you gain while being treated with inversion therapy. Inversion therapy technique has a very ancient history that goes back to Hippocrates, the Greek physician, when he realized that gravity could be useful for treating some pains and injuries, but this therapy was known to people only in 1960. If you tried to think deeper in the technique used, you'll notice that there's still compression on the spine, so where's the benefit? Actually, the new inversion techniques solved that problem, they invented inversion tables or boots, which hangs you upside down from your feet or ankles, therefore giving you spine, joints & connective tissues the ability to relax.