The first thing they have to do is improve their flexibility, for a couple of reasons. They need to be flexible to undertake the kind of exercises they need to be able to jump higher. They also just need to be able to increase their flexibility, because in the short sprints you take when you try to dunk a basketball, if you can imagine yourself running up to try to dunk on the rim, the higher you can bring your knees in a sprint, just like a sprinter running the hundred meters, the greater force you’ll be able to exert on the ground, especially with your leaping step.
Results: You need a 0 Inch vertical leap to touch the rim and 6 Inch leap to dunk considering that you have to jump about 6 inches over the rim to dunk. To accomplish that you have to leave the ground at a speed of 1.73 m/s vertically no matter how much you weigh. You need a force of 0 Newtons against the ground based on your weight to reach that speed assuming you bent your knees at an angle of 60 degrees. The force depends on how much you bent your knees. Check side bar.
Squats – start with the bar behind your neck, resting on your shoulders and make sure you’re standing with your feet shoulder width apart. From this position, slowly lower your body by bending at your knees. You’ll go all the way down until you’re in a deep squat and holding that position for two seconds. Then you can slowly rise back up to your starting position. Make sure you keep your back straight and you’re bending at your knees.
Any athlete who wants to maximize the height of their vertical jump should look to reduce their non-functional body weight (body fat) as much as possible. Though it's generally not recommended for youth athletes to go on a calorie-restricted diet, they should look to make healthy food choices. A good starting point for this is 40% of calories from carbohydrates, 30% from protein, and 30% from fats.
The force-velocity profile can be described by three elements: (1) maximum strength, (2) maximum velocity, and (3) the slope of the force-velocity gradient, because this is what determines whether the balance between force and velocity is optimal at the desired speed for force production. Each of these factors is an independent predictor of vertical jump height.
A more accurate method would be to use a Jump Tester (like these here.) The problem with these, obviously, is that they are way too expensive. In fact, the only scenario in which I recommend using one of these is if you’re a coach, trainer, or athletic director who is purchasing it to test a large number of athletes over time and who needs as accurate of a number as possible for scouting purposes.
Some days I would be doing leg exercises — you want to give yourself a 48-hour break between heavy lifting involving any given part of your body, to give yourself time to recover. Some days, I’d go out to the track and do a track workout like sprints. I was avoiding doing long-distance running, because I didn’t want to develop slow-twitch muscles. I wanted to concentrate on fast-twitch muscles. And then for fun, on the weekends, I would play soccer or pickup basketball. I was becoming a better athlete because of this. Not only was I faster and stronger, but I was also more confident, in terms of just the run of play in any of these team sports, because I was more athletic than I had been.
At the competitive level (i.e., the NFL and NBA combines), vertical leap is measured using a “jump tester”—a tripod with a series of thin plastic sticks one inch apart. If you have access to this equipment, it’s your best bet for getting an accurate measurement. A cheaper, more feasible option is to do your jump next to a wall and mark the highest point you touch with a piece of chalk.
Dunking a basketball is a lot of fun, and for most of us that is really the only reason to do it. Especially when you are a shorter player, it is cool to see the looks on the big guys’ faces when you do something you really ought not to be able to do. But let’s be realistic here: If you want to be a good basketball player there are many, many skills that are more important to spend time on. For most of us, the ability to dunk is an insignificant part of our game.
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), the computer can calculate his or her vertical jump based on the time in the air.