I suggest you get a copy of 'Winning Running' by Peter Coe.
"The following are two suggested under-distance standards to be met by first-class 800m and 1500m athletes before major competition commences:
- 200m in 22 to 22.5 seconds (ideally 21.5)
- 400m in 46 to 47 seconds."
I quoted that straight from the book.
Coe often did workouts of what is known simply as multi-pace training:
- 4x1500m or 3x2000m @ 5000m pace
- 8x800m @ 3k pace
- 16x200m @ 1500m/mile pace
- 4-6x400m @ 800m pace
- 2x300, 4x200, 4x100 all @ 400m pace
- 1000m + 800m + 600m + 400m @ 1500m pace
Peter Coe's table for calculating equivalent race times.
5000m 3X + 159sec
3000m 2X + 36sec
800m (1/2)X - 2sec
400m (1/4)x - 6.5sec
Where X = 3:40 for 1500m.
According to Coe, "this is the minimum acceptable range for a well-trained runner. Said Aouita, Steve Ovett, Steve Cram, and Seb Coe could all do it...this 1500m time of 3:40 is chosen as a reminder to a young but improving male athlete that any significant progess that he hopes to make will depend on meeting at least the 800m and 3000m times, and that anything better will require even better 400m speed."