When tendons elongate to a greater extent during a jumping movement that is preceded by a countermovement, the muscle lengthens less. This produces two effects. Firstly, the greater elongation of the tendon means that more elastic energy is stored during the countermovement, which is then released in the subsequent jumping phase. Secondly, the smaller elongation of the muscle means that countermovement depth can be greater for the same shortening velocity in the subsequent jumping phase, because the muscle never lengthened that much to begin with. Since shortening velocity determines force, this allows the same muscle force to be produced, despite the larger joint range of motion.

A vertical jump is defined as the highest point an athlete can touch from a standing point jump, less the height the athlete can touch from a standing position (standing reach height). The best place to start with your vertical jump improvement is testing your vertical jump. This will serve as your reference point to see how you’re increasing your vertical.
Even so, the back squat does differ in important ways from the vertical jump. Primarily, it involves a much greater trunk extension turning force, because of the barbell weight on the upper back, and this likely contributes to the more hip-dominant nature of the squat over the vertical jump. Secondly, it is often performed to a deeper depth, which can alter the relative contribution of each of the hip extensors to the movement, because of their different leverages at each joint angle. And thirdly, it only involves accelerating up to midway through the movement, while the vertical jump involves accelerating right up until take-off. This also affects the relative contribution of the hip extensors, as force production will be required in the jump even when the hip is nearly fully extended, while this is unnecessary in the squat.

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.

I scoured the Internet looking for guidance. There are dozens of sites promising a path to dunking, most of them coded at the dawn of the Web. It was daunting finding one that seemed legit. I ended up paying $67 for the Jump Manual, an online program offered by Jacob Heller, a trainer with a 42-inch vertical who counts NBA players among his clients, according to his website. Next, I ordered a pair of Strength Shoes. You’ll remember these if you’re a basketball player of a certain age—the ridiculous-looking training kicks popular in the ’90s, with a platform under the toe that places your bodyweight on the balls of your feet.
This study has several limitations. First, dopamine is a less potent vasopressor than norepinephrine; however, we used infusion rates that were roughly equipotent with respect to systemic arterial pressure, and there were only minor differences in the use of open-label norepinephrine, most of which were related to early termination of the study drug and a shift to open-label norepinephrine because of the occurrence of arrhythmias that were difficult to control. Doses of open-label norepinephrine and the use of open-label epinephrine and vasopressin were similar between the two groups. Second, we used a sequential design, which potentially allowed us to stop the study early if an effect larger than that expected from observational trials occurred; however, the trial was eventually stopped after inclusion of more patients than we had expected to be included on the basis of our estimates of the sample size. Accordingly, all conclusions related to the primary outcome reached the predefined power.
Data on hemodynamic variables and doses of vasoactive agents are shown in Figure 3 and Figure 4 in the Supplementary Appendix. The mean arterial pressure was similar in the two treatment groups at baseline, and it changed similarly over time, although it was slightly higher from 12 to 24 hours in the norepinephrine group. The doses of the study drug were similar in the two groups at all times. More patients in the dopamine group than in the norepinephrine group required open-label norepinephrine therapy at some point (26% vs. 20%, P<0.001), but the doses of open-label norepinephrine that were administered were similar in the two groups. The use of open-label epinephrine at any time was similar in the two groups (administered in 3.5% of patients in the dopamine group and in 2.3% of those in the norepinephrine group, P=0.10), as was the use of vasopressin (0.2% in both groups, P=0.67). Dobutamine was used more frequently in patients treated with norepinephrine, but 12 hours after randomization, the doses of dobutamine were significantly higher in patients treated with dopamine. The mean (±SD) time to the achievement of a mean arterial pressure of 65 mm Hg was similar in the two groups (6.3±5.6 hours in the dopamine group and 6.0±4.9 hours in the norepinephrine group, P=0.35). There were no major between-group differences in the total amounts of fluid given, although patients in the dopamine group received more fluids on day 1 than did patients in the norepinephrine group. Urine output was significantly higher during the first 24 hours after randomization among patients in the dopamine group than among those in the norepinephrine group, but this difference eventually disappeared, so that the fluid balance was quite similar between the two groups.
At pickup the next night, buoyed by the previous day’s accomplishment, I found a regulation ball that had good grip, one I could palm, and in between games, when no one was looking, I dunked for the first time in eleven years. If some dunks are described as thunderous, this one could be best described as a gentle fart in the breeze. But a dunk’s a dunk—and I had dunked.
Though improving jumping technique may add a couple inches to an athlete's vertical jump, good landing technique is even more crucial. The landing is when almost every jumping-related injury occurs, not the jump itself. For this reason, athletes should spend a significant amount of time learning to land in a balanced position that distributes the impact of the jump equally across all joints of the lower body. This position should look almost identical to the take-off position.
In the 2011 NBA contest, Los Angeles Clippers power-forward Blake Griffin completed a self-pass off of the backboard prior to elbow-hanging on the rim. A number of other variants of the elbow hang have been executed, including a lob self-pass, hanging by the arm pit,[23] a windmill,[24] and over a person.[25] Most notable are two variations which as of July 2012, have yet to be duplicated. In 2008, Canadian athlete Justin Darlington introduced an iteration aptly entitled a 'double-elbow hang', in which the player inserts both forearms through the rim and subsequently hangs on both elbows pits.[26] Circa 2009, French athlete Guy Dupuy demonstrated the ability to perform a between-the-legs elbow hang; however, Guy opted not to hang on the rim by his elbow, likely because the downward moment could have resulted in injury.[27]
The method described above is the most common and simplest way to measure one's vertical jump, but other more scientifically accurate methods have been devised. A pressure pad can be used to measure the time it takes for an athlete to complete a jump, and then using a kinematics equation (h = g × t2/8),[4] the computer can calculate his or her vertical jump based on the time in the air.