Each player must stand infront of a mat with a medicine ball held above their head.
He/she then squats, holding the ball above their head, then stands and throws the ball into the mattress as hard as they can.
When squating the back muscles must be kept straight.
When throwing this drill will work the player's arm flexors.
New hitters rarely miss because of their arm. They miss because of their feet. Build a reliable approach, then time it with your setter.
When your hitter gets stuffed, five teammates standing and watching is how you lose the point. Good attack coverage turns a blocked ball into a second swing.
Coaches spend hours correcting arms in serve receive when the real fault is almost always the feet. Fix the movement and the platform fixes itself.