Exactly how much slower than your 200m PR should your 1st and 2nd 200m be when running the 400m?
typically 2-4 seconds but it depedns on the runner for example an 800 guy who runs a 48 may run 23 and 25 and a 200 guy who runs 48 may be closer to 22 and 26.
sorry i msread the question as opposed ot youur 200 PR you normally should go out around 1-1.5 seconds slower. So for a 22.0 200 runner 23.0-23.5 would be a decent split.
That depends on what kind of 400m performance we’re talking about.
For example, for a 48.0 female 400m runners, the first 200m is run in 23.0, and the difference with 200m PB is 1.0.
For a 52.0 performance, it’s 24.8 with a 1.3 difference.
The standard deviation is of course greater when performances are lower as we found runners with very different abilities and tactics. Also, surprisingly, i’ve not been able to find typical pattern between runners with a 200m or a 800m background. So i think that the concept “first 200 slow for 800m runners and fast for 200m runners” is a myth. It tends to be the opposite seeing Torrence, Jackson, Brisco or Cheeseborough who were sub22 runners, and had a 1.6-2.2 difference between the first 200m and their 200m potential of the moment. On the other hand, Kratochvilova, Guevara and Quirot had a 0.7-0.9 difference!
All this from performance analysis of female races, so that’s the way it is, not a model or ideal way to run.
Should the second split aim to be in the same time as the first?
Same halves i.e. 25sec first halve and 25sec second halve doesn’t mean even pace.
example 12.9+ 12.1 + 12.2 + 12.8 = 25.0 + 25.0 = 50.0
The second 100m is always faster the first, and last 100m is always slower than 3rd. If not there’s a problem in effort pattern.
Aiming to run 12.5 + 12.5 + 12.5 + 12.5 is nonsense.
Anyway, 25 + 25 isn’t the easiest way to run 50sec, the best is to do 24 + 26.
As of right now my PB is 23.91, so what would you say I should be going out in…at this point?
I don’t know what your 400m goal is 400 stud, but with some good speed endurance you should take it out in 25.0-25.5 and bring it home in 27.0-27.5 I’d say. So you would be looking at around a 52-53.
But it is true what Charlie always says, speed, speed and more speed. The only way you are going to run faster in the 400 is if you decrease that 200 time. If you work really hard on the speed and get it to sub 23 then I think, with speed endurance added, you will be able to run sub 50.
Just my two cents.
My goal is <51.0 and my 200 goal is <23.0 so I think if I hit my 200 goal then my 400 goal will be a sinch.
That has been my experience. High 22’s = about 49 in the 400m. Low 22’s puts in you in the 48’s 
So if I do manage to hit high 22’s I SHOULD be able to get <50.0
SWEET!!!
Now you have to be realistic, I agree with what Chris30 says but there is such variation. I have seen a 22.4 guy run sub 48 but I also know that there are some sub 22 guys who can’t break 50. It’s a matter of having the speed and the speed endurance. If you can run 22.9, thus going through 200 in 24.0 in a race, hopefully you will be strong enough to come home in 26.0. A 50 flat. But you could be fast and not last in the final 200 or even final 100.
Using myself as an example, this past summer I ran 22.3 legal and 21.9 wind aided. In my one and only 400 I took it out in 23.0 (very easy) I went through 300 in 35.8 (still on good pace) but then just died in the last 100m and came home for a 50.29. So my last 100m was in 14.2. Thus I split 23.0 and 27.0. Not the best conversion. Now keep in mind that the 400m wasn’t my focus this past summer and had I trained my speed endurance and focused on the 400 I am fairly confident that my speed would have allowed me to run 48s.
That little anecdote is just a warning that you still need to put in the effort and can’t just relax and believe that the sub 23 will just equate to a certain time. Bring your speed up, but ensure good speed endurance and you will fly in those 400s.
I’ve seen it myself, too. I hear what you’re saying. All I’m saying is that if I can run <23.0 then I SHOULD be able to run about 50. and that’s my goal. If I’m not somewhere around there with a <23.0 200m time then I know I have work to do, but it’s a goal and something I at least know is attainable.
I think how well you prepare during the GPP and SPP will play a big part in the last 100 meter of your 400. Especially with a fairly young training age. If you were slack in your GPP/SPP you will likely have a few problems in the last half of the 400