Cycling and swimming are actually the best way to retain and maintain the mobility and strength of an ACL deficient leg.
Avoid all open-chain exercises as this means your lower leg could twist and possibly cause other damage. Leg press machines where the feet are firmly placed on a plate as you push are good and will probably feature in your rehab anyway. Leg extension machines can be contra indicated, so it depends on what type of machine you are going to use.
Squats are a hot topic in as much as how deep and with what kind of weights. Again better to ask someone who knows what is damaged in your knee what and how.
Hamstring curl machines always featured in my rehab protocols so I am assuming they will not be a problem.
You are probably better to err on the side of caution with weights - go for low weights but high repettitions. Increase the number sets you do rather than boost the weights.
How often - is as often as you would usually train but don't go mad by doing the training all day every day!
A mixture of aerobic and anaerobic (strength and endurance) is probably the best mix in a week, unless you are a bodybuilder or similar. Spinning in a gym is a good activity for all aspects and swimming with and without arms/legs can also help with your general fitness. Using just a flutter kick builds up the hip extensor strength as well as the smaller muscles around the knee itself. A dolphin kick may not be the best thing for your knee right now but can be a pwerful workout for the whole leg if done properly.
Sue
