When I started to work on the video tool that measures vertical jump, I had to dust off my old textbooks to learn about the relationship between hang time and jump height. And to my surprise, it turned out that the vertical jump is a great (and interesting!) example of the laws of physics at work. You can really learn about the relationship between velocity, acceleration, forces and hang time. Definitely more interesting than the average example of your physics textbook!
7. Antman EM, Anbe DT, Armstrong PW, et al. ACC/AHA guidelines for the management of patients with ST-elevation myocardial infarction: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee to Revise the 1999 Guidelines for the Management of Patients with Acute Myocardial Infarction). Circulation 2004;110:e82-e292[Erratum, Circulation 2005;111:2013-4, 2007;115(15):e411.]
To start the test, you need to stand with your right side against a wall. If you have access to a chalk board or a vertex (the measuring tool used by biokineticists), it makes this easier, however, you can use an outside wall. For the first marking, stand in your training shoes with your right hip against the wall. Reach up with your right hand to touch the wall at the highest point possible (while keeping your heels flat on the ground). Mark this point with chalk, as this is your “standing height.”
During the takeoff an athlete generates forces that ultimately result in a vertical velocity high enough to leave the ground. We have shown before, that this vertical velocity reaches 0 at the peak of the jump, and it is easy to show that the velocity is exactly the same during landing as it was during takeoff (but directed in the opposite direction).
For one-footed jumpers, the ball is generally transferred to the non-dominant hand just before or upon take-off; for two-footers, this transfer is often delayed for milliseconds as both hands control the ball to prevent dropping it. Once airborne, the dunker generally transfers the ball from non-dominant to dominant hand beneath a raised leg. Finally, the ball is brought upwards by the dominant hand and slammed through the rim.
During the 1940s and 1950s, 7-foot center and Olympic gold medalist Bob Kurland was dunking regularly during games. Yet defenders viewed the execution of a slam dunk as a personal affront that deserved retribution; thus defenders often intimidated offensive players and thwarted the move. Satch Sanders, a career Boston Celtic from 1960 to 1973, said:
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 common, low-tech plyometrics method is performing box jumps, where the athlete jumps repeatedly from the floor to the top of the box and back again. By concentrating on the mechanics of the jump, directing propulsion from the balls of the feet and thrusting with an explosive extension of the legs, the ability of the athlete to land lightly and immediately return to the floor enhances motor control over the movement.
The phrase "slam dunk" has entered popular usage in American English outside of its basketball meaning, to refer to a "sure thing": an action with a guaranteed outcome, or a similarly impressive achievement. This is related to the high probability of success for a slam dunk versus other types of shots. Additionally, to "be dunked on" is sometimes popularly used to indicate that a person has been easily embarrassed by another, in reference to the embarrassment associated with unsuccessfully trying to prevent an opponent from making a dunk. This ascension to popular usage is reminiscent of, for example, the way that the baseball-inspired phrases "step up to the plate" and "he hit it out of the park," or American football-inspired phrases such as "victory formation" or "hail Mary" have entered popular North American vernacular.
After four months of failing to pull off anything even resembling a real dunk, the planets aligned on Aug. 9: After at least 19 failed attempts that afternoon, I dunked a soccer ball on a middle school court whose rim measured 9' 11". (The original basketball, incidentally, was a soccer ball, property of Dr. Naismith’s employer, Springfield College.) Video from that afternoon shows me standing there, looking confused, in the moment afterward. Did that just happen? Failing had become so routine that even this small success felt foreign.
Rope skipping is also a very basic form of a type of exercise called plyometrics. Plyometric exercises involve repetitive explosive movements, such as jumping up and down or catching and throwing a medicine ball. The idea is to execute the movement with as little downtime as possible between repetitions. This, in effect, trains muscles to be powerful and explosive, and utilize the kinetic energy inherent in athletic movements in the most efficient way.
I learned that insects are fucking awesome. There was an insect in particular that I was interested in called the froghopper, or spittlebug, that is basically one of the world’s top jumpers. It’s a survival mechanism. It can jump far, far higher than we can as a function of its weight, basically. So I learned that humans are quite modest in the jumping scheme of things.
En la introducción del comienzo y final se muestra la historia de los últimos treinta años de la doctrina de choque económico que se ha aplicado alrededor del mundo, desde América del Sur en la década de los setenta hasta Nueva Orleans después del huracán Katrina. Klein introduce dos de sus temas principales. 1) En donde los profesionales de la doctrina de choque tienden a buscar una pizarra en blanco en el cual plasmar su ideal de crear economías de libre mercado, en el que inevitablemente requiere normalmente una violenta destrucción del orden económico preexistente. 2) Las similitudes entre la crisis económica y la doctrina original de la terapia de choque, una técnica psiquiátrica donde se aplicaron choques eléctricos a los pacientes con enfermedades mentales.
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.
I think it’s the sort of thing that a lot of kids probably fantasize about, me included. Just like you might want to become an astronaut or something like that. I was always one of the tallest kids in my class, but I never really tried to dunk. And so as an adult, you start wondering a little bit about what sorts of things you left on the table, that you never really tried your hand at. And I got it into my head that I’d pick up this childhood fantasy of mine and see if I could dunk.
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. It is considered a type of field goal; if successful, it is worth two points. Such a shot was known as a "dunk shot" until the term "slam dunk" was coined by former Los Angeles Lakers announcer Chick Hearn.
“There’s something about dunking a basketball that lures us in,” he said, reflecting on his first jam, during lunch period his sophomore year at De La Salle High in Concord, Calif., back when his driver’s license read 5' 11", 112 pounds. “It stokes the imagination. It’s something you always dream of doing. I have a friend whose father, at age 50, is trying to dunk.”
Seventy-nine years later, the feat that Daley unwittingly named “the dunk” still flabbergasts. But how it felt to Fortenberry, a pioneering barnstormer whose name we’ve forgotten despite the gold medal he and his teammates won in 1936, remains a mystery. “He never talked about being the first person to dunk and all that,” says 65-year-old Oliver Fortenberry, the only son of Big Joe, who died in ’93. Indeed, the famous dunkers throughout history have been either reticent on the subject or unable to adequately express how it felt to show Dr. Naismith that he’d nailed his peach baskets too low. After more than a year of rigorous research on the subject, I’ve concluded that the inadequacies of modern language—not the ineloquence of the dunk’s practitioners—are at fault. In the eight decades since Fortenberry rocked the rim, words have repeatedly fallen short in describing the only method of scoring, in any sport, that both ignores one of its game’s earliest tenets and, in its very execution, carries a defiant anger.
The vertical jump is defined as the highest point that the athlete can touch from a standing jump, less the height that the athlete can touch from a standing position. The measurement of the jump is flawed if the athlete is permitted to take one or more steps before jumping, as the athlete will convert some of the energy developed in the step taken into the force of propulsion that generates upward lift. Basketball has numerous legends and other urban myths concerning the seemingly superhuman leaping ability attributed to certain players; one such player, former University of Louisville star Darrell "Dr. Dunkenstein" Griffith, was reputed to possess a 42 in (1 m) vertical leap. It is likely that the average National Basketball Association player 6 ft 6 in (1.97 m) or shorter has a vertical leap of between 25 and 30 in (0.63 and 0.75 m); taller and heavier players will usually not be able to jump as high.