The answer is both!

The question?  “What do you test?”

My rationale is this: if you have a skinny athlete who adds 15 pounds during a two-month period, but his vertical jump stays the same, a VJ-only assessment protocol won’t tell you that he gained a ton of peak power.

As such, we use vertical jump in conjunction with body weight to calculate estimated peak power output using the Sayers equation.  While recent research demonstrates that this equation typically underestimates peak power, the important thing for me is reproducibility (not complete accuracy).

As an example, last week, I posted a video of Tim Collins, a Cressey Performance athlete and Toronto Blue Jays prospect who vertical jumped 38.7 inches at his final test of the off-season.

More impressively, he went from 27.9″ on October 3 to 38.7 on February 4 while adding six pounds to his frame. Without factoring in the six-pound weight gain, we are looking at a 34.8% improvement in peak power.  When we factor it in, though, it becomes a 37.2% mprovement.  That 2.4% might seem insignificant to some, but the truth is that it’s an impressive result for an entire year’s hard work for many elite athletes with less window of adaptation ahead of them.

Vertical jump is a measure of relative power.  Peak power is a measure of absolute power.  Both have implications in the world of baseball, as you have to decelerate your body weight on each pitch, and you have to sprint, which is a function of the force you put into the ground relative to your body weight.  Conversely, the push-off during pitching and the hitting motion are all about absolute power.

So, all things considered, you’ve got to track body weight and vertical jump, then plug them into an equation.

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