A:Answer To begin with have only had chair two weeks
Totally satisfied with purchase. Bought it at half price.
Now to address your issue.
Imagine sitting in normal chair, press a button, back of chair starts to lower, feet start to raise.
The back will lower to approximately but not equal to 90 degrees, the feet will raise to that level.
It does not invert you and this is the max, when you lower back, halfway between 90 and start position you can use that position.
(sort of a recliner)
So, start position, recline position, not exactly 90 position.
Hope this helps
There are a few videos on You tube that further illustrate
