Because of my nerve deficit's - and my body's way of compensating to walk & function in general - I am not able to go for walks or runs outside in order to get a good workout. I often fall down, whether it be on a flat surface, downstairs and I've even been known to fall up the stairs. Those type of activities and contact sports only increase my pain and throw off my bodies alignment. So, one machine which has been wonderful in allowing me to get in my cardio without hurting my back, legs, hips, knees or feet, is the Elliptical machine. I highly recommend this piece of equipment to anyone with joint problems or a spine condition.
Building core and back strength is also extremely important when it comes to this condition. I have found Pilates to be an excellent form of strengthening, stretching and even a decent cardio workout. Just like Yoga, you can really tailor this activity around your abilities and opt out of those exercises which cause pain. A bonus for this type of workout is that it helps to naturally realign one's body and spine.
Another terrific form of cardio - which is easy on the body & back - is swimming. While I love swimming, I do have great hesitancy towards doing so, especially in public, as I have foot drop, and therefore, trouble walking without shoes. And, walking with bare feet on a wet slippery surface, is a disaster waiting to happen! While I'm on the subject of taking a dip in the pool, I would like to mention something which was shared with me by my surgeon many years ago. For those with Spondylolisthesis, whom have not had any surgery, specifically fusion, working in a pool with light leg weights over an extended period of time can help to lessen the degree of slip by slowly stretching the spine. I was told of one patient who had a grade 5 and worked in the pool for two years before having a fusion surgery to stabilize the condition. She had her Spondylolisthesis fused at a grade 1 following those 2 years of dedication. Amazing!
Finally, I recently started the newer exercise program designed by the trainer Tracy Anderson, called "The 30 Day Method" and the "Tracy Anderson Method." Like with Pilates and Yoga, there are some exercises which are not conducive to this spine condition, but they can be avoided. Most of the work is done on the ground and it really helps to strengthen your accessory muscles, and in addition, surprisingly gives you a challenging cardio workout as well.