Mandy Froehlich, M.S., 500-RYT on Instagram: "Prevent the hump back one behind the back clasp at a time! 👉 Big Tip: Concentrate on moving the shoulder blades together as you clasp. These bones need to move so they can get truly get stronger! Tight rhomboids that don't contract as the arms move back (these are the muscles that move the shoulder blades together) can create a humpback. Furthermore, if you DON'T move your shoulder blades when moving the arm like this you might hurt your…