Peter Attia sugests one workout a week being at VO2 max, with the rest of the workouts building out a solid aerobic base. The workout he suggests for the hard one is 4 minutes on, 4 minutes off, 4 times. This is something I haven't done in years, and am a little nervous about (as in nervous enough to want to do this in an environment with an automatic external defibrillator).
He describes this a little bit like I used to think of a 2000m test on an erg, but condensed. The first minute is relatively easy, if it's not, you've gone out too hard and are going to blow. Minutes 2 and 3 are really uncomfortable, and you only get through minute 4 because its the last minute and you can go for broke. I would suggest doing negative splits here, where you get progressively faster, but he admits that he is pretty much universally positive splitting.
The rule Attia uses is the 80/20 rule, so if you are going to do 5 workouts in a week, 4 of them (80%) ought to be base training, and 1 of them (20%) ought to be as I described above.
He also notes that he warms up significantly before doing this workout. I could see doing VO2 max after a full base training workout as a warmup.
I'm not a doctor, and this isn't medical advice... I'm also kind of OK with dying on a treadmill as a honorable end. I might strongly consider actually asking my doctor before doing this. There is something called a cardiac stress test which would get you up to this level of exertion in a controlled way in a medical environment where a resuscitation team was nearby.
The final note is that I'd be tempted to start slow, like wearing a heart rate monitor play with where you are in the zones. Don't go for broke (dead?) all at once on the first interval.
