If you get higher then it will take longer for you to come down = more distance. There does need to be forward momentum so that you don’t go straight up and back down in the same spot i.e high jump! The run up gives you the momentum and I suppose the idea is to jump up and forward at take off. I believe there is an optimum take off angle but I can’t remember what it is off the top of my head.
Once you’re in the air you can’t do anything to make your jump further, only shorter!
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