Finally, to make things even more complicated, it is likely that the roles of the lower body muscles may differ according to if: (1) the jump is maximal or sub-maximal, (2) long-term training has occurred, and (3) the individual has a “hip-dominant” or a “knee-dominant” technique. Indeed, the vertical jump is more dependent upon the hip extensors in maximal jumps, compared to in sub-maximal ones. And after long-term jumping training, the increase in the amount of work done in the jump by the hip extensors is related to the increase in height, while the increase in the amount of work done by the knee extensors is not.
You can assist in recording your score by holding a piece of chalk in your had and using it to mark the wall. If the wall already has horizontal lines, such as a brick wall, it will be easier to mark your jump height. Have as many attempts as you need to get the best possible score. Practice your technique, as the jump height can be affected by how much you bend your knees before jumping, and the effective use of the arms.
Dunking became a game again. After my closest misses I’d hop around and swear like a golfer whose playoff putt had lipped out. These outbursts were no longer harsh self-admonitions but celebrations of my progress, acknowledgements that I was getting tantalizingly close. I could feel my legs gaining in bounciness. I could feel my hips, quads and calves learning to fire simultaneously. My original lobber returned to the scene and suggested I try dunking in the morning instead of the evening, when the batteries in our old bodies are as low as the ones in our phones. I added this sage advice to the long list of microdetails “that help you steal inches,” as Todd had phrased it months earlier. “A quarter inch here, a half inch there.”
An important component of maximizing height in a vertical jump is attributed to the use of counter-movements of the legs and arm swings prior to take off, as both of these actions have been shown to significantly increase the body’s center of mass rise. The counter-movement of the legs, a quick bend of the knees which lowers the center of mass prior to springing upwards, has been shown to improve jump height by 12% compared to jumping without the counter-movement. This is attributed to the stretch shortening cycle of the leg muscles enabling the muscles to create more contractile energy. Furthermore, jump height can be increased another 10% by executing arm swings during the take off phase of the jump compared to if no arm swings are utilized. This involves lowering the arms distally and posteriorly during the leg counter-movements, and powerfully thrusting the arms up and over the head as the leg extension phase begins. As the arms complete the swinging movement they pull up on the lower body causing the lower musculature to contract more rapidly, hence aiding in greater jump height. Despite these increases due to technical adjustments, it appears as if optimizing both the force producing and elastic properties of the musculotendinous system in the lower limbs is largely determined by genetics and partially mutable through resistance exercise training.