You have probably heard of people who do very short workouts—sometimes just a few minutes—but still get the same benefits as you do going for a long run or sweating through an hour on the elliptical machine. This type of exercise is called high-intensity interval training (HIIT), which involves short bouts of very intense exercise separated by periods of rest or light activity. I have written about this type of training previously (and before that, too), but a new study that has been in the news this past week makes revisiting this topic worthwhile.
Previous research has shown that shorter exercise sessions can be as effective as the typical 20-60 minutes of continuous exercise people commonly do to lose weight or get in shape. The catch is that these shorter bouts of exercise must be done at a very high intensity to promote improvements in maximal exercise capacity (called VO2max) and endurance by enhancing heart function and causing changes in the muscle itself. These adaptations can lead to improved fitness, performance, and health.
For example, in one study the intervals were as short as 30 seconds of all-out, maximal exercise separated by rest periods, for a total of just six minutes of exercise per day. Other studies employ slightly less intense intervals for a total of 20 minutes of exercise per session. Another study found that a single 4-minute bout of vigorous exercise was effective. Taken together, these studies show that HIIT leads to adaptations in the heart and muscle and improvements in VO2max and endurance that are greater than that of more traditional, lower intensity exercise.
A new study published last week ( excellent low-sci description here) showed that sessions of one minute—yes, 60 seconds—of intense exercise can match the fitness and health benefits of more traditional workouts. Subjects in the study completed three, 20-second bouts of all-out, near maximal exercise separated by two minutes of light cycling on a stationary bike. After doing this three times per week for 12 weeks the changes in heart rate, muscle function, and blood glucose regulation were the same as those experienced by subjects who did the same number of 45 minute workouts, but at a lower intensity.
Before you get too excited about only needing to exercise for a minute at a time, there are a few points to keep in mind. First, this type of exercise is very intense and may not be right for everyone. At the very least, it is likely to be uncomfortable. Second, exercising at a high intensity may not be a good idea if you are not already in good shape or have other health problems, like high blood pressure. Third, HIIT may not be the best way for you to meet your exercise goals. If you are trying to build endurance for a marathon or long distance bike ride, you really do need to focus on longer duration exercise at least some of the time.
Finally, if you add up the total exercise time, including the warm-up, time between intervals, and recovery, the “one minute” workout is more like 10 minutes of exercise. This is still shorter than what you would probably do anyway, but certainly not a true 60 second workout. And this type of training doesn’t do much to help you meet other fitness goals including improving strength and flexibility, so you will still need to spend additional time in the gym. The bottom line is that HIIT should be part of your exercise regimen, not the whole program.
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