The unprecedented study compared the workout sessions of seven healthy men with an average age of 25. Their respiratory gas and heart rate were monitored, and blood samples taken, while they performed the following scenarios:
- A 60-minute workout on a cycling machine, followed by a 60-minute rest period (single)
- Two 30-minute workouts on a cycling machine with a 20-minute rest in between, and a 60-minute recovery period at the end (repeated)
- A 60-minute rest period (for control purposes)
Meanwhile, the repeated trial caused a greater increase in free fatty acids and glycerol, which are released when stored fat is burned, than did the single trial. Also during the repeated session, levels of epinephrine increased and levels of insulin decreased much more than during the single session -- a combination that may have further contributed to fat breakdown.
Current recommendations by The American College of Sports Medicine to exercise for a duration of 45 to 60 minutes may therefore not be the most effective, the researchers say. Splitting up a longer exercise session with a rest period may be more beneficial, helping people to better manage and control their weight.
Journal of Applied Physiology 102(6):2158-64 June 2007
Science Blog July 18, 2007
The evidence continues to mount that shorter bursts of activity with rest periods in between is one of the most effective ways to exercise. This alternating technique, known as interval training or high-intensity interval training, has been around for decades but is experiencing newfound popularity as its benefits are publicized.
This most recent study confirmed that interval training results in more fat burned -- even when the session was not done at an extremely high intensity -- and a study earlier this year found that it can improve your cardiovascular fitness and your body’s ability to burn fat.
During my college years, and about 15 years after that, I used to do interval training, but stopped it and just did endurance training since I haven't regularly competed for 15 years. I had no idea that the interval training had so many other benefits.
Now however, as the benefits of interval training keep pouring in, I have been reawakened to the importance of short bursts of activity done at a very high intensity to reach your optimum level of fitness. Therefore, I now incorporate interval training (sprints) with endurance cardio training (running), pull-ups, dips and singles tennis (when I can find someone to join me!) You certainly don't have to run to achieve these benefits, and can receive similar effects using properly supervised weight training.
I believe that incorporating interval training into your exercise routine will be a welcome relief for most, particularly those who dread hour-long cardio workouts.
Although interval training requires intense periods of exercise (more intense than you may have normally done), the session is broken up with periods of rest, so it really goes by much faster yet produces excellent results. This technique should help just about everyone who uses it; just be sure to start out at your own pace.
So remember, along with some endurance cardio training, be sure you are also incorporating interval-type training and strength training into your exercise routine. As with many things in life, when it comes to exercise, having some variety built in will help you to get the most comprehensive results for your mind and body.