I'm going to jump into this discussion as I've been doing Pilates for more than 25 years. I purchased a number of DVDs so I could do it at home and also went to a weekly mat class in town. It stopped with COVID. At the same time we were in shutdown, I was overtaken with symptoms of PMR, an autoimmune disorder, which made all movement painful. Mat work wasn't possible. I managed a daily walk, though. Long story short, a year later, I've been diagnosed, gotten treatment - steroids - no more pain. Just diagnosed with osteoporosis though. In researching exercises for osteoporosis, I was surprised to learn that many of the Pilates exercises that involve SPINAL FLEXION can cause compression fractures of the spine. Lifting the head off the mat, abdominal curls, c curves, rolling like a ball, the saw, the hundreds, the helicopter, etc. with the head off the floor - are all dangerous. Carol Michaels is on YouTube and has excellent workout videos for persons with osteoporosis. I also found the attached folders at the National Osteoporosis Foundation website. I included yoga since so many Pilates exercises are similar. It's good for us to exercise, but we have to be aware that the wrong movements can cause us harm. All the Best and keep moving! tsc