Was supposed to do 2.5hr z2 today but was short on time so switched my 60min vo2 workout to today. This was my first build workout and first vo2 in months. Was going for 6x3.5min at 110%, first 4 were solid the last two were rough. In hindsight I’d probably be a little better off just doing 4 to start with and starting in the 14-16min range before ramping up to 20mins of work. My Friday workout will be 4x4 and we’ll see how that goes