I have been told I have chondromalacia patalla in my right knee. Will cross training with low impact excerising make this condition worse? I realize running may not be the best choice right now, but I don't want to be inactive if I don't have to be.
I would recommend non-weight bearing exercises such as swimming, or rowing. Cardio exercise that is weight bearing (walking/running) will cause a strain to be placed on the knees. However you may want to check with your physician to talk about prescription anti-inflammatory medication that may help to make exercise more tolerable. Over the counter NSAIDS may also be enough to allow you to exercise pain-free.
With Chondromalacia it is common to see individuals with weak or inhibited frontal plane stabilizers that cause a synergistic dominance of the hamstrings, quads and TFL as well as patellar misalignment or mal-position that may contribute to the pain associated with the anterior knee. I would recommend a corrective exercise program to help correct this. Use a foam roller on your hamstrings, quads and TFL and performs stretches for these muscles as well. I would also work on strengthening your glute muscles as well to help counter the dominant hamstrings.