When I was in my 20's, I could always jump 3" higher on a one legged running jump than a 2 leg jump. My max vertical back then was about 33" running jump. My brother was different. He jumped better on a 2 leg jump. He was 6' 1.5", 240 lbs. and was a shot putter in HS. He was able to squeak a dunk on a 10' rim.