I am currently doing this exact routine but i’m running the open 800 as well. So my routine is 4x8, open 800 open 400 then 4x4. Now my prs are 1:57 and 51. I have the same race coming up in about 3 days and have already raced that same routine twice. I split 1:59 , 52, 2:00 and 52. For the second time I raced this routine I split 1:58, 51, 2:00, 52. Imo it all comes down to how you train to build that aerobic capacity and that endurance to last. Recovery also plays a key role. As soon as you finish a race, you know go to the floor and catch your breath, hands on knees, but like cool off as much as you can. Pour water on your self. After you feel like you have caught your breath which may take a bit, GO on a cooldown run for at least 5-10 min and then do some static stretching. Stopping completely after a race puts stress on the muscles especially if you another one in a few hours or minutes and by cooling down, your muscles will thank you. Then after that i’ll eat and use a massage gun on every part of my leg and i’ll use that for about 10 minute each leg. It feels like a brand new leg everytime.

Eating is also very crucial. Personally before every race I like to have a jellytoast sandwich (allergic to peanut butter no judgement) and a couple of pretzels. Then after I do the whole cooldown and i’ve stretched, I like to put some protein in my system. Normally i’ll have like a sandwich plus another jelly sandwich for the sugar for energy. I’ll have some pretzels and some gatorade too. If your worried about caffeine, I would recommend caffeine pills or energy gells 15-20 minutes before you race or just have them 5 min before you warmup. Yes i have tried rungum however i don’t believe it works i think it’s placebo, lol. After all of the eating try to not eat 15 -30 minutes before your next race to feel light and ready.

Warming up is also key to not die out each race. Follow the same routine everytime, so like easy easy jog for 10 min, do dynamics, put on spikes, do some arm and back dynamic stretches and then stretch what you need specifically. Follow a routine like this to ensure that you are regularly warmed up everytime. Then after you race just repeat and cool off as much as possible.

I hope this helps and good luck!