From Hinshaw Endurance:
Run Workout 1: 800m Progression
8 x 100m
20sec b/t reps
3min b/t #1 & #2
.
Run Workout 2: 800m Progression
2 sets: 4 x 200m
60sec b/t reps
3min b/t sets
.
Run Workout 3: 800m Progression
2 sets: 2 x 400m
75sec b/t reps
3min b/t sets
.
Run Workout 4: 800m Progression
1 x 800m max effort