Thoracic spine scoliosis comes in various degrees of severity. Some of the most severe forms of scoliosis actually cause difficulty breathing because of thoracic insufficiency syndrome. If the movement of your chest wall is effected, then your personal trainer will want to limit the amount of strenous aerobic activity to a mild, brisk walk. And if you do have chest wall involvement, then blowing up balloons is actually a good way to condition the muscles involved with breathing.
Any form of scoliosis whether it is in the thoracic spine, lumbar spine or both can benefit from some spine stabilizaiton exercises that strengthen the core muscles. One of my favorite book that explains specific exercises for the spine in various degrees of difficutly is called Spine Stabilization by Rick Jemmett. I can personally attest that this book has a number of great exercises. A personal trainer should use this as a guide and avoid exercise that involve extreme ranges of motion.
And finally, don't forget about balance. Those with scoliosis usually have an altered center of gravity or plumb line. Because of being off kilter, people with scoliosis are at a higher risk of falling. There are many simple ways to help improve balance like practicing to stand on one leg.
That is your answer in a nutshell. Hope it helps keep you as active as possible.
Dr. Christina Lasich, MD