Tuck Jumps

Standing in place, jump up in the air and bring both knees up to your chest; grasp both shins with your hands when knees are at their highest; extend legs to land on both feet and immediately jump up again.
(No double pump on landing; the flexion to absorb your landing leads right away to the takeoff push.) Do the jumps as quickly and as high as you can.
The goal is to build explosive power in the quads, hamstrings, and glutes as well as quickness.