Hello all.
Couldn't help reading about the HIIT procedure. I started my "transformation" 6 days ago and have worked myself through 1 week of John's schedule. A couple of you have said that they feel their legs hurt whether you are on the treadmill or on a bike. I have the same problem, but I have found out (I hope this solution will stick, it's only based on what I have done so far) that if you ignore the pain which sets in during the first few minutes of the exercise and push yourself harder it goes away naturally after a couple of minutes and you can finish the exercise whether it's a 12 or 23 minute HIIT workout. Same pain set in after I worked out my legs, and they hurt like hell the next morning and the first 3 minutes on the bike, but around the 6:th minute the pain was "OK" and I could concentrate more on the exercise rather that let myself quit just because it aches.
I don't know if this works for everyone, I just thought I'd post something that might help someone.
Good luck to everyone and thanks again John.

P.S.(Sorry for the possible spelling or gramatical errors, I am from Sweden :) )

well if your going from no excersice to HIIT 7 days a week, thats faaaar too much, maybe start with some lower intensity cardio, then work up to HIIT, and you dont have to do it 6-7 times a week! more like 3-4

also make sure you do some good leg stretches when your done!

i agree with taffer, HIIT isnt something a beginner should start out doing. they need to do regular medium-intensity cardio, for a month or two, to get their heart conditioned. HIIT, if done PROPERLY, could potentially send a newbie into cardiac arrest because of the strain it puts on the heart. its like taking a car that has sit in the garage for years out on a 2,000mile race at 100 miles an hour. SOMETHING IS GOING TO BREAK!

we all want to lose weight, and lose it "fast". if we dont condition our bodies for some of the more advanced movements, we will get injured and taken out of the game. that will be a demotivator and cause many to not continue their program. very similar to me doing my deadlifts. i do them slow, and with lighter than normal weights because i want to ensure my form is proper so i dont break something.

remember, this is a marathon, not a sprint. work up to HIIT, dont just start doing it!

Dont try to do everything on the first few weeks. Your body is not used to the exercise so most muscles are going to get sore from different exercises and you can hurt your self if you do more than your body can handle...

I started running 2 miles on the first day and had to stop on the fourth day because I had alot of pain in my legs... Now I'm just riding a bike and getting my whole body used to regular exercise so I can go back to running when I'm ready. (1 or 2 months.)

I agree with the others to a certain extent, but if you can push through the pain and you're body isn't screeming out to you, no reason why you shouldn't push yourself.

I personally am being forced to work up to HIIT, my legs simply won't take HIIT at the moment. I've always had big sprinters thighs, even after 3+ years of doing nothing i was able to go into the gym and squat 150kg, and they just won't do endurance work.

I agree with you about pushing through the pain, when i start even a 30 min standard cardio the first 5 mins are the worst, my legs ache like hell and i feel like ima have to stop, but if i keep going and just concentrate on the next 2 mins, i get through it and can keep going for ages no problem.

Of cause, if you have real pain, from a pull or a strain, or a piercing pain, then you should stop. Pushing your limits and pushing an injured muscle are two different things.