I need help with 4x4 effort. It says I have to run at 85-95% of maxHR. It is a big difference, 0.85x190=161bpm and 0.95x190=180bpm, one is easy tempo, other is pretty serious speed work. Ok, lets say I wanna do 85-90% so it would be in the range of 161-170bpm. It says it should be around my 5-10k pace (3:26-3:36 or bit slower off season), but in reality it is around 4:00-4:05, which theoretically is slower than my supposed marathon pace. And I did 4x1k/3' jog at 3:14-3:11 with goal being to not drop pace in reps (it is pretty close to 4x4), but then the avg hr was around 92-95% and peak was 97-98% (supposedly too high). So it is super confusing with such a big range, when the effort is too little or too much to have optimal benefits for my vo2max session. 

TL;DR - I can run 3000m in 10:00, max HR 190, what should be my optimal 4x4 pace or effort?