Back problems? Joint stiffness? To relieve the pain take two Sarah Keys:
The Body in Action (Allen & Unwin, Crow's Nest, 2006)
The Back Sufferers' Bible (Vermilion, London,2000)
She's Australian (Crow's Nest is apparently in New South Wales) and the books can be hard to get hold of, but they're worth the trouble of finding. Actually it's not that much trouble if you use a service like Abebooks.
The exercises Sarah Key prescribes worked for both Paddy and me. I tried them when I had back pain a couple of years ago, and they helped me get rid of it. More recently, when my right wrist started hurting from my too-rigid grip on the fencing foil, the relevant exercises fixed that. I only have recourse to the books for specific problems, but Paddy does the exercises several times a week because he finds they keep his joints supple and pain free.
Paddy, who used to work as a doctor, says Sarah Key is obviously fascinated by anatomy as her books give excellent functional descriptions of the joints. (For all I know the knee bone's connected to the T-bone, but I trust his college gold medals - one of them was for anatomy).
Prince Charles, much battered from his polo days, wrote the Forward to TBSB, but don't let that put you off; he too commends the clarity of the explanations and the effectiveness of the exercises themselves.