Last month, I did high-intensity interval training on the treadmill.  Getting my target heart rate to the max (220-age, roughly) for 60-90 sec, alternating with slower segments.  Generally for me, this was 3.7 mph on treadmill at 7% grade for 10 min, then alternating 12-15% incline with 2% incline.  I strongly recommend using a heart rate monitor for this.

The great thing about using a heart rate monitor is that when you start out, you don’t over do it.  Many overweight/obese people are very out of shape, try to go to a spin class, feel like they’re going to die, then give up.  But if you try to exercise to, say 70-80% of your target heart rate, you’ll get an amount of exercise that is appropriate for YOU.  As you get more fit, your target pulse may stay the same, but you’ll see you’ll be able to go faster/longer/more incline.

The good folks at the NY Times explain the phenomenon well in a recent article.  The best part is, you get great results with a short period of exercise.  I was doing 20 min high-intensity interval sessions before my usual weight training.

Or even better, check out this video: