Friday, March 29, 2013

Vertical Jump 101







Vertical Jump 101

To begin, understand that the vertical jump is simply just a measurement of power.

WHAT IS POWER?

Power can be determined by a simple equation:

Power = Force x Velocity

To break it down just realize that power and explosive strength simply mean the ability to apply a given amount of force over a period of time.  The more force you can put out and the faster you can apply that force, the higher your power output will be.

In order to understand how to improve power, it helps if we to know how to manipulate each component of the equation, force and velocity.



When we most often think of force, the word strength comes to mind. In mathematical terms Force = Mass x Acceleration.

Simply put, if you move a larger or heavier mass or accelerate it more rapidly from point A to point B, you will increase force and subsequently, power output.  For our purposes however, no need to get overly technical! Its easier to think of the force part of the equation as your maximal level of strength.

Velocity- is the speed of movement.

Simply put, the greater the force or velocity, the higher the power output.

Its really not much more complicated then that.  However, before we move on, Id like to define some key terms that are all interconnected in the quest to improve power and jumping ability.  Youll see some of these terms periodically throughout this book.

Limit Strength- is simply the maximum force you can voluntarily apply. Maximum force is typically measured in the weight room with powerlifting being a classic example of a sport that measures maximum force.  Actually a better name for that sport would be
force-lifting or strength lifting.  Because of the slower velocities inherent when lifting a maximal load, powerlifters actually generate less power then athletes in many other sports. Other then arm wrestling and maybe tug of war, powerlifting is also about the only sport where maximum force is measured.

Absolute strength- is the maximum force one is potentially capable of applying. As you will learn later it is rare to see our strength potentials fully realized.

Relative strength- is the strength per pound of bodyweight
Rate of force development- Is the speed at which you can develop force. Starting strength- influences rate of force development and is the ability to
instantaneously turn on as many muscle fibers as possible when movement begins to take place.

Reactive strength- is also known as elastic strength, reversal strength or plyometric strength.  This is the ability to gather and utilize reflexive force during a movement when switching from an eccentric (negative) contraction to a concentric (positive) contraction.



Now lets use a real life example to see what the above complicated terms look like in real life.

WHAT STRENGTH AND SPEED REALLY LOOK LIKE




Bodyweight
Maximum force or strength
without time constraint (squat)
Max force put out in the
vertical jump (.2 seconds)
Athlete
A
175 lbs
400 lbs.
200 lbs.
Athlete
B
175 lbs
300 lbs.
225 lbs.

Look at the chart for a moment and try to decide which athlete would have an advantage in the vertical jump. Assuming both athlete A and B are the same size, you can see how they have very different strength patterns. Both of them weigh 175 lbs. Now look at the next row that says maximum force or strength without time constraint.  In this example we’re using a maximum squat since it is a slow movement and during a squat we have ample time to apply max force.  What we’re describing here is how much force these athletes can put out regardless of how long it takes them to apply that force.  A squat is a good example of that.

As stated, power-lifting, arm wrestling, and tug-of-war are some sports that measure this. In practically every other athletic event, there isnt enough time to allow true maximum force to be developed.  So in this case you see that athleteA” reaches a higher peak
force and he squats more weight, 400 lbs vs 300 lbs, yet if you look at the 3rd row, the amount of force he can put out in .2 seconds, which is the same amount of time it takes to complete a vertical jump, - Athlete As force output is lower then that of athlete B, so he develops force slower. Therefore, athlete A is going to be able to squat more than athlete B, but athlete B is going to smoke athlete A in a vertical jump test. Here’s why:

In the maximum squat or maximum force test, the athlete has plenty of time to generate peak force. It takes roughly .4-.7 seconds to develop peak force. On the other hand, movements like the vertical jump inherently occur very quickly, around .2 seconds.  So, how much force you can put out in a short period of time is going to determine performance.

Dont get too carried away with this just yet though. Although being able to apply force rapidly is a very useful characteristic, you still need to have enough potential force to tap into for anything to happen. The 63, 200 lb guy with a max squat of 100 lbs is not going to be dunking any time soon, even if he can apply all that force very rapidly.

Here is an example of what that athlete might look like on paper when we break his strength qualities down like we did above:


Bodyweight
Max force (strength) in the
Squat
Max force in vertical
jump
Weak
Athlete
200 lbs
100 lbs
95 lbs


You should be able to see that even though this athlete utilizes 95% of his potential force (95 lbs) within those .2 seconds, and has good rate of force development, he still doesnt have enough potential force to tap into for that awesome rate of force development to do much good.  He’s only capable of squatting 100 lbs and even though he’s able to use 95% of that in the vertical jump he’s still only putting out 95 lbs of force, which isnt going to do a whole lot to get him off the ground!

Now here is an example of what an ideal athlete’s maximal force and rate of force development profile might look like:




Bodyweight
Max force (strength) in the
squat
Max force in the vertical
jump
Ideal
Athlete
175 lbs
400 lbs
325 lbs

Even though this athlete is very strong he is also capable of utilizing a large % of that force in a very short time-span, which is ideal.  His max squat is 400 lbs. and he’s able to utilize over 75% of his potential force, or 325 lbs., at toe off.



Sources

Rippetoe, . Starting strength. 3. Witchita, Texas: The Aasgaard Company, 2011. Print.


Baechle, T. R., R. W. Earle, and R. W. Earle. Essentials of Strength Training and Conditioning. 3rd. 3. Champaign, IL: Human Kinetics Publishers, 2008. Print.



Rippetoe, M., and L. Kilgore. Practical programming for strength training. 1. 1. United States: The Aasgaard Company, 2006. Print.

Everett, Greg. Olympic Weightlifting for Sports. 1.1. Catalyst Athletics, 2012. Print.