And of course, it was too good to be true. At least the way the media reported it. I finally got my hands on a copy of this study today, and here’s the real breakdown of the exercise routines used in the study.
Both exercises started with a 7 minute warm up. After the warm up, the continuous group did stationary cycling at a workload equal to 70% of VO2 max for 30 minutes. After the warm up, the sprint group did an 18 minute routine that included 30 second cycling sprints at a resistance of 10% of body mass, followed by 4 min of light cycling for recovery. So basically, we’re comparing a 37 minute total continuous workout versus a 25 minute total sprint workout (when you include the warm-ups).
During the exercise and after 24 hours, the authors measured oxygen consumption, which is an indirect measure of metabolism (the number of calories you’re burning). They found that even though oxygen consumption was 150% higher during the continuous exercise compared to the sprint, after 24 hours there was no difference in total oxygen consumption between the 30 minute exercise and 2 minute sprint over that period of a day. Basically, the boost in oxygen consumption was higher after the sprint exercise which balanced out the higher oxygen consumption found in the continuous exercise during the activity.
Translation: Yes, HIIT can help you become healthier, help boost your metabolism and help you lose weight. And yes, technically there were 2 minutes total of sprints (four 30-second sprints) - but it was a 25 minute total workout between the warm up, sprints, and light cycling for recovery. HIIT is a great form of exercise, but you’ll need more than 2 minutes total to reap the benefits.
PS: We just sent our 2012 Challenge participants some more detailed information about this concept and some awesome sprint workout ideas to complete this week. Not a part of our 2012 Challenge? Sign up today! You'll get nutrition and fitness info emailed to you each week with a related challenge for you to tackle in your own life.