glad to hear it worked out. You should try a litte progression over 6 weeks (two sessions/week),
- week 1: two rounds, 400m runs
- week 2: three rounds, 400m runs
- week 3: two rounds, 600m runs
- week 4: three rounds, 600m runs
- week 5: two rounds, 800m runs
- week 6: three rounds, 800m runs
moderately increase the reps every second week and this will work like a charm. BTW I think Owen Anderson would be glad to hear it helped you kids, although I am pretty sure it was more the work they did before.