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.
“Put in the work. It’s muscle memory, first and foremost. Training­wise, people say, ‘You gotta do this, you gotta do that.’ I didn’t believe in that. I never worked on my legs in high school or middle school. I would just go through this routine over and over and over, visualizing that day when you dunk on the court. And then you live in that moment.”
A slam dunk, also simply dunk, is a type of basketball shot that is performed when a player jumps in the air, controls the ball above the horizontal plane of the rim, and scores by putting the ball directly through the basket with one or both hands.[1] It is considered a type of field goal; if successful, it is worth two points. Such a shot was known as a "dunk shot"[1] until the term "slam dunk" was coined by former Los Angeles Lakers announcer Chick Hearn.[2]
James Naismith, I learned, was a bit different. “I was only three when he passed away [in 1939],” said his grandson, James Naismith, 78, of Corpus Christi, Texas. “He was known as a tenderhearted man, but he also had”—the doctor’s namesake pauses—“the polite term is ‘firmness of mind.’ It’s kind of a family trait. He devoted his life to improving the lives of others through physical activity, through games. That took time.
Among the hundreds of lessons I learned during my youngest child’s first year of life was this: If you earnestly pursue dunking after your athletic peak years of 18 to 30, give or take, it can be done. You can enjoy what it feels like to dunk. You can even feel it more purely than I did, maybe without needing a lob from a friend, and hopefully without all the hand damage. But you should expect a long, frustrating, demeaning war of attrition that pits mind, body, spirit against the most oppressive, unrelenting opponent of them all: gravity. The sun rises and sets, the tides creep in and out—even taxes and death seem negotiable nowadays—but gravity remains constant, forever pounding our shoulders, stooping us shorter as we grow gray, never letting up—no matter what NASA tweets.

Unfortunately, I’m not the 6' 7" son of a Hall of Famer, so I had to resort to desperate devices—like Hennessy, an infamous and inexpensive cognac that, according to one of the two NBA players who recommended it to me, “will give you that Yah! That bounce. That little bit of meanness you need.” The little minibar-sized bottle that I downed 30 minutes into an intense session of dunk attempts on a sweltering day last summer, had no effect other than scorching my esophagus, giving me a headache and releasing from my pores an aura that, as my six-year-old put it that evening, “smells like medicine.”
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.