500 Freestyle?

Hey bud, how old are you? I was a competitive swimmer for years and when I was 12 years old, my 500 freestyle was 4:57 and my lifetime best was 4:40. I was a backstroker and grew up training with Aaron Peirsol, Amanda Beard, and more olympic medalists and qualified for Trials in 2000. It sounds like you have a good 100 and 200 but not enough stamina for the 500. The 500 free is like a distance sprint event. You have to be able to go pretty hard the whole time. The best thing to do is train for pace 100's for example, if you are trying to get under 5:00, do 10x100 on 1:20 holding 59 or better on all of them. Keep training till you get there. Once you are able to do that set without a problem, your 500 will excel because most likely your first 100 is going to be around 54-55 effortlessly. Then your next 4 100's can be at that 59 marker. That will give you an end time of around 4:51-4:52. Little things make a huge difference too. Streamline, not breathing off the walls, fast turns, kicking, all the things your coaches always harp you on. That stuff works.

It seems that you don't have enough stamina to hold on. A 50 second 100 free is quite impressive. Pay lots of attention to your longer sets at practice and focus on pacing yourself and holding a stroke count of three. I never really was a free-styler but I wish you the best of luck. You have lots of potential and keep working hard- we may be seeing you at the Olympics one day.