Treadmill as weather not good. A 3km warm-up then 10 x 30 seconds off 30 seconds. Then a 3km warm-down to finish.
I was running the 30 second efforts at sub 3:10 pace and it felt very comfortable. The heart rate wasn't even getting into my recovery zone during the 30 second effort. Feeling good.
All up 7.6kms.