In the process of driving a flat shot which is above the waist, the wrist will pronate. If the shot is below the waist the wrist will supinate. These wrist rotations help with the power of hitting the shuttlecock with efficient amount of a strike. There will also be a greater advantage with more leverage, meaning it's easier to hit the shot if the shuttlecock is near the joint. (file:///C:/Users/Richard%20Tran/Downloads/2233-4616-1-PB.pdf)