In light of the fact that I have completely torn my right ACL and 2 meniscus off the posterior bone just 3 weeks before the BC fitness Championships I had competed in, I am going to talk about about working the knee while injured or sore. I am to compete again in 2 weeks on this knee, hence my majorly modified, grounded routine.
Whether you are chronic like arthritic or dealing with an acute issue knees can be funny and should not be ignored.
Depending on your issue rest and exercise need to be balanced properly but you do not want to just leave it and not do anything. Heat and or Ice are also applicable but which you do when is up to you and the physio, the knee that day will dictate. Anti-inflammatory meds are also useful.
The knee joint depends on movement in order for oxygen to get in there through the blood and movement is how you do it. Synovial fluid is our natural lube and it needs you to move that knee in order to fill the knee and do its job. There are many levels and choices for movement/exercise.
Most cases in knee problems want you to have a certain alignment where the mid knee cap lines with the outer top edge of foot, this prevents knock knees. Alignment, speed of work and control is crucial.
Recumbent bikes can be very useful for this.
Normally you would modify exercises and choose specific ones applicable to your issue and would not do full range of motion and have the right amount of weight bearing to suit your needs at the time.
Wobble board and 1/4 press on the wobble is one of the best ways to help the knee if you are able to put weight on the leg. You can do it near a wall or doorway for support and work up to balancing without. These boards are now popping up on places like walmart etc at lower costs than when they were only available through rehab.
I got one for 12 bucks at superstore, but it was seasonal and so you have to keep your eyes out.
These are useful even for those of you without knee problems. First of all they are great for injury prevention and make for a great addition to your workout and balance which is something we need to train more and more as we age.