Dear Nizar Abu-Hamdeh,

your questions include different aspects:

1)      relation between the maximal weight of Barbell Squat and the maximal force developed in the legs extension movement - this relation could be influenced  by the athlete’s Barbell Squat execution technique;

2)      relation between the maximal strength of leg extensors and the T&F high jump result - this relation is strongly influenced by the T&F high jump execution technique;

3)      the nature of the leg extensors maximal strength; in other words, what kind of training method has been used for the maximal strength increasing - if this strength has been developed using Bodybuilding methods (with muscle hypertrophy), it could not assure the explosive strength increasing.

So, there could not be a general and universal guideline on how much relative strength is enough for athletes to maximize vertical jump height.

But to have information that could help you, you should find specifics experimentals results of in publications. These experimental results must be referred to the parameters of high level T&F high jumpers group: the relation between their results in high jump, vertical jump (Abalakov) and the maximal weight that they are able to lift in Barbell Squat in the same day.

Unlikely, I have not these data.

Yuri Verkhoshansky