Piano riff or playing the piano involves you placing your foot flat with equal weight on the inside and outside of the foot. Raise the big toe up by itself (same as toe swapping). Keeping the big toe up, raise up the second toe to join it. Then add the third toe, the fourth, and the pinky. Try to make each toe come up separately. Once all the toes are up off the floor, start putting them back down one at a time starting with the little toe. You may need to help guide your toes to do this using your hand. Keep riffing them up and then down, like someone playing scales on a piano.
Doming-start again with the foot flat on the floor. Try and press the underneath side of the small knuckles of the toes down into the floor. This should make the main knuckles closest to the floor raise up like a dome The toes need to stay long and straight. When the toes curl under, it’s the extrinsic muscles working, not the intrinsic. It’s harder then it sounds! These movements will be a little frustrating at first, but they will strengthen the “core” muscles of the foot. Plus they make a good party trick! Of course, if you have any foot pain that is not resolving, please seek advice from an experienced Podiatrist or Physiotherapist.