Quote cod'ead="cod'ead"OK you asked for it.
I intend to enroll at my local gym becuase I'd like to get back running again. Up to 20 years ago I'd run 25 miles a week on average then when I quit refereeing, I quit all training too. Quite apart from wanting to turn what was until recently a Party Seven back into a six-pack, I'd also like to get back running again. The main problem with running is I have osteo-arthritis in both knees (the left being marginally worse). Since losing the weight I've realised just how much I have missed getting out on the road, I used to find it very therapeutic, not just physically but mentally too. I used to work off a lot of frustrations by pounding tarmac. I've read on t'interweb that OA shouldn't be a major drawback to running, even at my age and that by exercising and building up the muscles around my knees, that can mitigate any further damage. I also intend to run on grass as opposed to concrete.
Is this a folly or is there a realistic chance of me getting my running shoes back out again?'"
There's a chance, I suppose, though running often isn't thought to be one of the better exercises for those with osteoarthritis in the knees because of the impact on the joints.
You're certainly correct that strengthening the muscles around the joint and doing some aerobic exercise to improve suppleness ought to help the condition, but lower impact activities (swimming/cycling) along with some resistance work tend to be recommended for most people in your position.
That said, much depends on the individual and how severely the condition affects them personally. I think it's always important when exercising to do something you enjoy, as there's a much greater chance of adherence than by doing something you actively dislike. I would advise you to speak to your GP and see whether he/she thinks going back to running is a good idea for you. I would advise extreme caution when running outside though - if your knees are weak, the slightest unevenness in the running surface can jar the joint and set you back. If you get the nod from the doctor, I'd try using a good quality, well sprung treadmill, at least to start with.
I'm sure I don't need to tell you this (I'm going to anyway), but whatever you do end up doing, it's vital that you start slowly and build up gradually. Another thing you might like to try is doing different types of exercise over a couple of weeks, and keeping a diary of how your joints feel one, two, twelve and twenty-four hours after exercise. This should help you to ascertain which exercises are likely to cause you the least problems as you progress.
There are exercise referral schemes in place in some areas, and your GP may be able to refer you to a PT with specific training in dealing with your condition.
Hope that's of some use, let me know if there's anything else.