well after the first thread, and doing some thinking and jumping I came to the revealation of the possisble reason my verticle back in highschool increased alot in the beginning then came to a screaching halt in my later years at attempting to increasing it was overtraining it. It seems logical that you can overtrain yourself in jumping as well as lifting.
Back then i was jumping about every day playing basketball most days of the week and working hard, to hard to increase it, in turn i seriously hurt my knees.
well about 10 years later, and my knees have almost fully recovered (naturally with no surgery) i have been playing basket ball once a week for a cardio workout.
my verticle has been increasing slowly, at least back to were it was around a 38" verticle. i was able to dunk on occation, very softly.
well last week i came pretty close to dunking it, and am feeling more confident that my verticle is increasing still.
one thing i learned which helps me alot is to have my legs warmed up before i start jumping, with a good run, or game of basketball, after they fell slightly tired i have more spring in my legs and can jump easier and higher.
I have been working hard on my ATF squats to, doing well on increasing my set weight (265x10 from 225x10 3 months ago), but my max unfortunatly hasnt been moving up (315x1 to 325x1) still not sure if this though will help my leaping ability though.
but i think the main thing that is moving my verticle up is that im not overtraining it, i think once or twice a week work well