I am a physically fit male who has been a competitive obstacle course racer and weightlifter. I have recently taken up yoga to improve my flexibility and cannot sit cross legged with a straight back. My body, especially my lower back strains just to keep me upright. Folds are absolutely impossible. I can round my back and lean over a bit but that’s it. I don’t have any hip problems, squat poses are fine and I have an otherwise strong back. Thinking back, I don’t think I could sit this way as a child either. Has anyone else experienced this issue and identified a cause and treatment?