2 Rounds:
500m fast
500m Slow
400m fast
400m Slow
300m fast
300m Slow
300m fast
200m Slow
100m fast
100m Slow
Rest 5 min
Total: 6000m

OR

2 Rounds:

300m fast

300m Slow

300m fast

200m Fast

200m Slow

100m Fast

100m Slow

Rest 5 min between rounds

Total: 2400m