Different muscle groups in your body are more important than others in the jumping process. As you probably know, the quadriceps (muscles on the front of your leg) are the most important muscle group and provide most of the power. However, calves, arms, hamstrings, deltoids, lower back, and hips provide a lot of thrust as well. I've broken it down like this: Two foot jump 63% Quadriceps 20% Calves 2% Deltoids 15% Arms One leg jump 50% Quadriceps 25% Calves 15% Hamstrings 10% Arms   As well, the hips provide a lot of thrust (especially in 2 foot jumps). Because the hips are a hard area to strengthen, it is very important to have good flexibility in the hips. A good range of motion is essential in striving for maximum jump height.