We have recently returned from our preseason training camp where we used the Power Tool extensively.
One confusing thing we found was why one player would record a high peak velocity score but not necssarly a high peak power.
Another player would record a similar peak power but their peak velocity would be much lower.
How is this possible?
Peak velocity and peak power are very different measures. Peak velocity is the result of ALL of the energy that has been applied to a movement. Whereas peak power is measured by finding the highest rate of work during any instant of the movement. This could be a peak recorded for just 20 milliseconds! So its very common to see high peak velocity not correlating with with high peak power. It is entirely possible to get a short, sharp component in the lift with a very high peak power, that actually contributes very little to the final velocity.
Another way to consider this is to look at the physics:
Kinetic Energy(or work done) = 1/2 x mass x the square of velocity
In a dynamic movement the athlete has transferred the maximum amount of energy to the bar when velocity peaks.
and because :
Power = work/time
Concentric mean power for a lift (jumps are different due to zero power in flight phase) is total work/concentric time.
Peak power = (work done in sample period)/(sample period)
So mean power captures all the energy in its calculation, but peak power only captures a tiny window where the rate of doing work peaks. What you will find, is that individuals with high mean power will have corresponding high peak velocity because all of the energy in the system is accounted for. This is one of the reasons why we like mean power and peak velocity so much. Mean power is a measure of the quality of the the entire lift.
But what about all the research using Peak Power you say!
Even though most research focuses on peak power, we still prefer mean power. Peak power is an easy measure to obtain automatically with simple peak detection software or even a spreadsheet. We believe this is a major contributor to the common use of peak power in research – its widely used because it’s easy. Fortunately mean power is now easy to measure due to the automated rep detection in GymAware. This has opened up a new area of cool research possibilities like this one ,where mean power for a team correlates to average RPE.