My 400 times are 55 high/56. My 800 PR in the beginning of the season was a 2:14. Currently, I am a sophmore in highschool and want to improve my times by a lot. What could I be able to run by the time the season is over and by the time I am a junior or senior. What should I do in the offseason too?
Your 400 speed indicates a maximum potential of 2:05//2:06, but with more training your 400 speed will also improve, so the sky's the limit here. To maximize your 800 potential you need to do distance oriented training. Let's face it: the 800 is a distance event, at least mid-distance. 56 and 2:14 suggests you are grossly undertrained on the distance end of things. Incorporate some more aspects of mile and 2mile training and then you should be able to improve a lot. Longer intervals with shorter rest should help you.
I think I was running 55/2:10 by the end of my sophmore year, which might be in your ballpark. By senior year I was 51/1:58 on a low milage highschool program, so maybe that is around your highschool potential. I also trained for the mile mostly.
I think the problem is you are doing a terrible, terrible double. Almost anyone who does the 800 approaches it from the distance side—and guess what, with your 56 400m time as a sophmore you are just simply not a 400 person. There are piles of freshman/sophmores running 50-52 that only improve a couple seconds in 4 years. Seriously, just train like a distance runner all year, do cross country but still keep up your speed with at least 10 fast strides every other day. Whoever started the trend of doubling these races is just enabling high schoolers to have bad training (because like you sure as hell wont be doubling this in college).
Work on distance and worry about the 400 later once you get a lot stronger. It shouldn't be a focus when you run so slow.
You are underperforming your 800m base on the 400m time. You should be closer to 2:05-2:10 if you are running 400m in 55-56. So, depending on when your season is over maybe approaching that before it's over.
800 meter is more like a long sprint than a distance race. It's like the 400, exact the last 100m is a full extra lap.
Get this in your head now: There is no off-season. So if you are committed to getting better then understand that you are either gaining fitness or losing fitness. I'm not saying don't take rest days or time off but understand prolonged periods of 2 weeks or longer without an athletic stress and you will notice significant drops in fitness.
As far as a training system goes, I think you would do well in Lyle Knudson's training scheme. You can read a good summary of his system here:
http://www.letsrun.com/forum/flat_read.php?thread=1661115
I think it maybe worthwhile to use this system as it's more strength and speed based which is prefect for an 400/800 type runner. High milage can come later as your training age increases. I also like that it's a programmed 2 week cycle that adjusts as your training progresses and not dependent on a targeted time frame like a periodized system.
Strength training needs to be a priority for you. Look at doing a the suggested lifting regime with the Knudson scheme but you need to get stronger so that you can get faster. Try to focus on single leg exercises.
I agree. No one should focus on doubling 400/800 unless their section/conference is weak in either event. I've got a teammate who can win the 800 in our section, and his 400 is good for 3rd, but his mile time is totally disproportionate. If he decides to pursue running in college, his 2:05 800 will show more promise than a 53 400. All tge 400 does is show that he has room to improve in the 800.