By Brian B. Parr, Ph.D. ACSM Certified Clinical Exercise Physiologist
The next time you are at the gym sweating through an hour on the elliptical machine or going for a long run to improve your fitness, think about this: you may be able to get the same benefits with just a few minutes of exercise. Sound too good to be true? Depending on your goals, high-intensity interval training (HIIT) may work for you. It’s not as easy as it sounds, though. The exercise must be done at a very high intensity, often in short intervals separated by periods of rest or light exercise. Let’s explore the research, benefits, and drawbacks of HIIT.
Exercise to improve cardiorespiratory fitness typically involves 20–60 minutes of moderate to vigorous exercise done 3–5 days per week. This type of exercise is common for people who are training for an event like a 10k run since it leads to improvements in maximal exercise capacity (called VO2max) and endurance by increasing heart function and promoting changes in the muscle. These training adaptations are important for performance in endurance events like running, cycling, and swimming that require sustained effort. Traditionally, this type of training is also used by most people who are interested in losing weight or getting in shape, even if they aren’t competitive athletes.
Research and practical experience have shown that shorter HIIT sessions can be effective for improving fitness, too. For example, in one study these 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 (still 90% of maximal heart rate) intervals for a total of 20 minutes of exercise per session. The results show that HIIT leads to adaptations in the muscle and improvements in VO2max that are greater than that of more traditional, lower intensity exercise.
A more recent study 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. Clearly, intensity matters when it comes to fitness and health benefits of exercise!
Does this mean that high-intensity training is right for you? It depends on several factors. First, the risk of injury during intense exercise is greater than during more moderate exercise. At the very least, exercise of this intensity 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 diabetes, high blood pressure, or heart disease. Third, HIIT may not be the best way for you to meet your exercise goals. If you exercise to lose weight your emphasis should be on duration, not intensity, to burn calories. 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, 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.
For most people, there is little harm in trying some higher-intensity exercise, even just one day per week. In fact, many group exercise classes are designed to be a high-intensity workout, so this might be a good way to add more intense training sessions to your exercise routine. The bottom line is that HIIT should be part of your exercise regimen, not the whole program. Keep in mind that 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.
Here is an example of a “one minute” HIIT workout used in a research study. The researchers in this study used a specialized cycle ergometer because the work load is easy to monitor, but you can do it on any stationary bike, treadmill, or rowing machine. The key is to alternate very intense work intervals with light recovery intervals. Keep in mind that “intense” is a relative term, so the resistance or speed you use may be different from what others do.
If this seems like too much, the good news is that HIIT is scalable. You can even incorporate HIIT intervals into walking or jogging outdoors. If your normal exercise routine is walking (or jogging) at a comfortable speed, try adding intervals of faster walking (or running). You can keep track of your time or use landmarks like blocks, lamp posts, or driveways to mark the start and end of your intervals. Going uphill and downhill is also a good way to introduce high-intensity work and recovery intervals into your routine.
As with any new type of exercise, listen to your body. If it feels like you are doing too much, slow down or rest. Doing something you don’t enjoy or that leads to injury won’t help you in the long run, no matter how effective the exercise may be. Lasting health and fitness benefits come from adopting an active lifestyle that includes regular exercise to improve endurance, strength, and flexibility, even if it isn’t HIIT.
Dig Deeper: The One Minute Workout: Science Shows a Way to Get Fit That’s Smarter, Faster, Shorter By Martin Gabala and Christopher Shulgan A decade ago, Martin Gibala was a young researcher in the field of exercise physiology – with little time to exercise. That critical point in his career launched a passion for high-intensity interval training (HIIT), allowing him to stay in shape with just a few minutes of hard effort.
The One Minute Workout includes the eight best basic interval workouts as well as four micro workouts customized for individual needs and preferences (you may not quite want to go all out every time).
The One Minute Workout solves the number-one reason we don’t exercise: lack of time. After all, everybody has one minute to spare.