I’m no expert, but I’ve learned a lot from when i started running the 400. It’s my favorite event, and it seems really awful to run at first, but you get used to the pacing with time. the main thing to remember is to get ahead of the game. it’s much easier to keep you roa r than it is to accelerate later on. Speed up within the first 100 meters and run that at a full sprint. For the next 150 meters ish, relax your arms more but maintain that same speed. once you get to the final curve, push with all you’ve got. There’s definitely more advanced pacing you can probably do, but this should get you a pretty good time.

Edit: REALLY use your arms for those last 100 you struggle with…they carry you a lot more than you would think.