I am not sure were all of this going, but VJ is a good indicator of explosive power, not anything else. I'm 33 and don't train and I can still get 30-31 inches regularly. When and if I get back to training I would go back to around 33-35 inches. I wouldn't find it surprising that any hardcore recreational athlete or HS athlete can jump 35-40 inches. It's a pure power skill, that does take some learning to perfect but not as much as say a sprint start or doing a t-test. The best thing a VJ tells you if an athlete has potential at explosive activities. The one foot takeoffs in LJ, TJ, HJ, and PV are highly complex skills compared to a VJ test.