Today's swim was off the programme as I didn't have time for a long swim and shouldn't be doing fast intervals. So it seemed perfect to do a CSS time trial. That needs good effort for 400m and 200m. So it would be interesting go see if I could beat 8:00 minutes.
After the warm up I set off straight into the 400m with an excellent, possibly too fast pace. For the first 300m I was clearly faster than 2:00min/100m but then slowed. It didn't help that I lost track of lengths and so did 2 extra, which also meant that mentally I saved energy more than needed. The last 3 lengths were slow and so I completed in 8:00.5 minutes which is a personal best but still not better than 8:00 minutes!
After a brief a breather I did 200m in 3:58 minutes. Using the swimsmooth CSS calculator I should aim to train at 2:01min/100m.
So for my long session the theory is that I should aim to include 1200m, across a few sets, at this pace to work close to lactate threshold.