For athletes participating in many sports, the ability to jump higher could be the difference between getting a lot of playing time and sitting the bench. Jumping, from a physics standpoint, is more complex than these athletes realize. The action combines energy, inertia, mass, and momentum, with physiological and biomechanical factors. Understanding the science that go into jumping can help athletes improve their jumping ability.
First, let’s take a look at what happens to the body when we tell it to jump. Obviously, it takes more strength, energy, and ability to execute a standing vertical jump than it does a running jump. That is because the speed helps to build momentum. Speed is the result of the muscles contracting. The faster they contract, the greater the torque, or rotation of the arm or leg around the joint. If the muscle contraction and torque are channeled in the right direction, the body can achieve lift.
Our bodies are heavy, and only way for a heavy object to defy the gravitational pull of Earth is for it to have the speed and strength to break this force. But everyone’s body is different and its ability to generate speed and strength varies greatly. While training and conditioning can improve an athlete’s vertical leap, the athlete is also limited by genetics. Muscle make up also factors in. People who are naturally longer and leaner tend to be able to jump higher because of their muscle make up and because they weigh less. They are able to generate more velocity in relation to this body mass. Yet this is can be changed. The more an athlete trains, the quicker the muscle fibers react.
Additionally, an athlete’s muscles need to be flexible in order for them to produce enough speed. Muscles with more mobility are better able to act like a spring and propel the body off the ground with enough force to catch some air. While some people are more flexible than others, with a proper training routine, it is possible to significantly increase muscle flexibility and mobility.
Interestingly, to jump higher, an athlete should have flexible muscles, but the opposite is true of their tendons. The reactivity, or stiffness, of the tendons is the ability of the tendons to resist the pull of the muscles. This adds to the spring-like action of the muscles.
Principles of physics apply to an athlete’s jump, too. The accelerated speed of gravity is 9.8 meters per second per second…the squared part is due to the acceleration. For an athlete to jump off the ground at 9.8m/s/s, it means he or she will be moving in an upward motion for one second. Afterwards, the speed reduces to 0m/s because the force of gravity quickly counteracts the upward motion and sends the athlete back to the ground. So it stands to reason that the faster an athlete is at the moment when he or she leaves the ground, the longer it will take for gravity to catch up to the jumper. That translates to a higher jump with more hang time.
Lastly, there is the sequence of actions that led up to the jump that can play a role in the height the athlete achieves. These types of biomechanics include the arm swing, the hurdle, and joint sequence.
Good athletes know that a good, powerful arm swing is one of the keys to a high jump. The body’s arms, pumped in the right manner at the right time, help to propel the torso in an upward motion. This takes some of the body mass off the legs and allows them to push-off the ground harder so the jump gains more acceleration.
For a running jump, the hurdle is the action the athlete takes when transitioning from the run to the jump. It looks like a little skip, but it is really an action that helps to maximize the power and momentum from the jump and turn it into vertical lift. In a hurdle, the power comes from the strength of the legs pushing off the ground.
In jumping, the biomechanics of the body’s joints come into play. As the athlete approaches the jump, his or her legs contract tightly, like a loaded spring. To get the most from the jump, the body must uncoil each joint from the top down. That means the arms should spring first, followed by the hips, then knees, and lastly, the ankles and feet. Doing so, gives the athlete more time to push off the ground and builds up the speed of the take-off. Combining this uncoiling action with the arm pump and the jumper is utilizing the optimal actions for achieving maximum height.
Jumping is a vital skill for many athletes. The ability to jump higher can turn a benchwarmer into an all-star, but athletes without natural jumping ability shouldn’t despair. It is definitely possible, with proper training and repetition, for a person to drastically improve his or her jumps, in turn making them a more valued athlete. The physics and mechanics that factor into the action of jumping are complex but maximizing each factor can help the athlete soar to new heights.
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Sky, J.B. “The Science Behind Your Vertical Leap.” USA Basketball. 8 Apr 2015. Web. 4 Sept. 2018.
Tober, Jacob. “Why Can’t I Jump High” The Science Behind Vertical Leap,” Core Advantage. 3 May 2017. Web. 4 Sept. 2018.