Hold on. Am I correct in reading that you are getting noticeable lactic production after about 1200m of tempo, namely 100m repeats in 19 seconds? If that is the case, how long are your rests, and if not, can you give me the specifics?
In trying to get myself into some sort of less horrendously poor fitness level, I have been running tempo: 3x10x100m in 17seconds, with 40seconds between reps, and 8minutes total between sets in which I do some push-ups, pull-ups (on the handy soccer goals), and ab work, with about 3min rest at the end of it before the next set of 100m runs. I could probably manage 100m in a blistering 12.8 or so (don’t laugh).
I get very tired and my heart rate gets to about 185 (max is about 225) towards the end of each set, but I don’t feel signs of lactic acid production. Could that just me not noticing it?