J F K. Had knees over toes on his book over 60 years ago, but this position was then mistakenly advised against for over five decades. If this hurts, don’t work through the pain. But do learn how to scale this ability. With just about any stairwell you can elevate your foot, assist yourself, and work on this ability with less pain. This combination of split squat and squat at the level that doesn’t hurt is now helping people all around the world.