15/F I play tennis and it causes knee pain. What can I take to strengthen my knee joint so it won’t hurt as much? Or what can I take to alleviate the pain? Thanks!

My right knee has arthritis. The pain comes and goes. I love jogging and tennis but it just kills me. I hate to give those up but will if it gets too bad.
But is there any good knee braces on the market that might alleviate the pain and prevent more damage?

I wanted to work out and exercise this summer to get in shape for tennis and lose a few lbs, however i just got runner’s knee, which gives me mild knee pain on the left knee. Is there any cardio exercises i can still do effectively while not overusing the knee?

I am 58 year old I love to play tennis, swim, and walk around the neighborhood for fun. Unfortunately, I have found that my knee and elbow have been hurting, and I am looking for something that will help my joints. Can anyone recommend something for me?

Thank.