We don’t test the vertical jump to see how well we jump. We could almost care less about that. So, why do we test the vertical jump?
It lets us know explosive strength of the athlete. “Explosive strength is the ability to exert maximal force in minimal time” (Westside).
If sport requires a high demand for explosive strength, we need to train it. Who are some of the best athletes at each game? The ones who are the most explosive.
To train it, we test our jumps. If our maximal strength goes up (aka a 1 rep max squat), our explosive strength doesn’t always go up. For an untrained individual, yes a strength increase immediately leads to a jump increase, but with the last 2 years of data, we started seeing at around the 3-5 month mark with our phase 1 athletes that absolute strength increases were no longer carrying over as efficiently to explosive strength. That is part of how we decide when it is time to move an athlete from phase 1 to phase 2.
The weight room is to make an athlete better for sport, not just better in the weight room. You must study, research, and track data in order to know when things need to be changed. Data never lies to you.
1- https://www.westside-barbell.com/blogs/the-blog/how-to-increase-explosive-strength