Adirondack Chairs may be the absolute WORST chair for anyone. Any chair where your ass is below your knees is bad, uncomfortable, taxing on every bone between. They look absolutely awesome out in your yard, but do not sit in one. A nice solid patio chair suits me fine.
@JoeSeadog IME, Adirondack chairs are quite comfortable IF you sit in one that happens to fit your physical shape. But they are all slightly different and finding one that fits you personally is a crap shoot.