I get like this doing 12 minutes of HIIT on the stairs.
Draw your own conclusions.
I do a routine very much similar to what lostboy describes, and it MELTS fat.
I hold my heart rate at around 150 to 160 for nearly 20 minutes.
Is it hard? You frigging bet. Does it hurt? Oh, yeah, it burns, especially if you take a break. But...you get used to it, and you better believe that I'm fit, too.
It's just like running bleachers.
You wanna' be a stud? Do the stud workouts.
Running bleachers is nothing like tennis, badminton, or even rowing. Doing stairs invokes 7 TIMES as much loading as walking. It's down and out bad ass for getting in shape.
At 12 minutes, I'm in a lather. If you can do HIIT over 15 minutes, you aren't doing it right. I sometimes only do 8 minutes, and it's enough.
Endless hours of blah cardio is for dummies. You want results, you need to EAT, and getting busy with some HIIT.
You wanna burn fat, AND increase your cardiac threshold as you grow older? Do HIIT.
I usually do only one session of HIIT a day, unless I'm not as lean as I want, in which case I'll do one just before bed.
I also speed up my weight workouts, a bit, but, HIIT is the ticket for a strong ticker, being able to pig out, and staying lean, and growing large.
If you wanna' be small, run marathons, lose bone, and muscle, and NOT develop your cardiac threshold...doing steady state cardio....oh, yeah...and throw in the impact injuries of running. LOL.