So I'm now moving towards extending the run - I actually pretty much need to as time is running out for Bath! It was a 4k build up with four 200m/r200m reps to finish. 6k in all. Managed to keep the heart rate a little lower tonight, or more accurately the peak wasn't quite as high. Up tomorrow is the 9k of the second stage of the Tour de Zwift, followed Friday by stage 2 of the bike version (hopefully).