what am I ready to run

Sun, 5/27/24-

65 degrees, with some humidity

I initially thought that I might try 3x400 in 60 sec...with 10 min break between efforts. I thought about 2 sets of negative split intervals of 300 in 48, 500 in 1:24, and 400 in 66 with 100 walk/100 jog (2:15) in-between repeats and 1200m/9:00 jog in-between sets OR its slimmer cousin, 2 x (200 in 30, 400 in 68, and 300 in 48 with 2 min btwn efforts and 800m jog/6 min btwn sets). 

This was before I saw John arrive...then Bruce. I knew there was no way they would go for the first two workouts as is. The third one, the "slimmer cousin," could have been a go, but I let it go. Instead, I tossed the opportunity to call the workout to John.

John recommended that we run 300m in 45, walk 200m, run 200m in 30, walk 100m, 5 min rest. Two sets. Because our 400 times vary widely, I mentioned that we would be running at about 90% 400 race pace.

I managed a comfortable 45-mid (200m walk in 3:30), 29-high (100m walk in 2:30), 14-mid (5:30 rest), followed by 45-mid (200m walk in 3:30), 29-mid (100m walk in 2:30), 13-mid. I'd classify this workout as moderate.

A 45.4 300m would place me at 95% of 57.75, my recent 400m (split...Penn Relays). A 47.6 300m would place me at 90% of the same time.

A 45.6 300m seconds for me would put me at 90% race pace of a 55 sec 400.

So...my question is whether my 45-second 300s represent 90% of race pace or 95%. Was I running at 90% of 95% of my 400 race pace? Asked another way, what am I ready to run in the 400? 57? 56? 55?