What prevents your ability to jump high?

Im a basketball player with a fairly big vertical, I can dunk and all that...but I notice one day I can jump really high and dunk and the next day or two I do not come close to dunking. What's going on with my muscles or what not?|||This is common in everyone, for example do you think that runners of any distance are able to tie or set personal bests everyday. No on somedays they are faster than other days.





As for your jump, it could have been your condition prior to playing (maybe you were stressed, or maybe you didn't stretch enough), but more than likely your vert simply fluctuates between a certain range.





I guarantee that if you asked Usain Bolt to run the 100m everyday for the next one hundred days, at least one of those times would be over 10 secs.|||I would tend to agree with most of the other answers here. Your performance each day will not be the same. Your body will be more (or less) tired on some days than others. You will eat better some days than others (this can have a big effect). You will just be more "focused" on some days than others. Every day can't be the same. Even professional athletes do not perform the same every day.





Lebron James may score 50 points one night and 12 two nights later. Albert Pujols may hit three home runs one game and strike out three times the next night. That's just the way it is.





What you are looking for though is that the general trend of your vertical jump is improving. To ensure that this happens, you should be using a program that will help you improve. The site listed below has a lot of good information on how to jump higher. It also reviews the top vertical jump programs currently available and tells you which one is the best.|||Maybe you are not well stretched or warmed up. BTW, sometimes you can have spasms in your back that affect your performance even when they don't hurt.|||Their own body weight and leg muscles are not developed enough!|||It could be the effect the moon has on Earth. If the moon comes closer to earth, gravity on Earth is slightly stronger.|||Leg Muscle.|||maybe your adrenaline was just pumping really hard