High-intensity interval training, commonly referred to as HIIT, is starting to get more attention lately as new research confirms the benefits of increasing the intensity of small, manageable portions of existing workouts rather than increasing the time spent exercising. Some people are even seeing superior results by trading some of their longer workouts for shorter periods of high-intensity work, despite less overall time spent exercising.
Current exercise guidelines include moderate-intensity aerobic activity for 150 minutes per week (or 75 minutes of vigorous activity per week) and strength training at least twice per week. HIIT can be incorporated into these activities.
Think of moderate-intensity exercise as breaking a sweat while being able to carry on a conversation. With high intensity exercise, like in a HIIT program, you briefly work hard enough that you can’t carry on a conversation. Your heart rate nears your estimated maximal heart rate. Then you slow down for a rest.
A quick and easy way to estimate maximal heart rate (MHR) is 220 minus age. For example, someone
who is 50 years old will have a maximal heart rate of about 170. This can vary by about 20 beats per minute in either direction. You can get a better idea of your own maximal heart rate over time as you check during your own workouts. For instance, if the same 50-year-old can maintain a HR of 170 during a long workout, his or her MHR is likely much higher than that.
What are the benefits of HIIT?
In a 2011 review of 24 studies featuring HIIT, the authors found that several health outcomes were the same or better with HIIT when compared to continuous moderate-intensity exercise. Aerobic fitness, for example, was greatly improved. After two months of HIIT, participants enjoyed improved HDL cholesterol (the good cholesterol). After three months of HIIT, participants enjoyed improved blood sugar and sensitivity to insulin, lower blood pressure, and improved weight and abdominal fat. Participants in HIIT programs overall spent less time on exercise to achieve these benefits. Also, HIIT caused the body to burn more calories during the workout, as well as for two hours afterward.
What does a HIIT workout look like?
If you usually ride an exercise bike, warm up as usual. Then, sprint as hard as you can for 30 seconds. Stop and return to a more comfortable speed for 4 minutes and 30 seconds. Repeat the sprint and rest four times total for a 20-minute workout.
If you are a walker or jogger, start with your usual warm-up. Then jog or run at a speed that increases your heart rate for 4 minutes (or less). Return to your usual speed for 4 minutes. Repeat this three times for a 24-minute HIIT workout. When you are just getting started, you can do a shorter period of high intensity and increase as you are able.
You can also get creative in the middle of a walk by taking 30 seconds to a few minutes to do jumping jacks, jump up and tap a high branch, or run up a hill before resuming your usual activity.
If you don’t have 20 minutes to spend, you can still get the benefits of HIIT with this 6-minute workout. Warm up for 2 minutes. Then alternate 30 seconds of high intensity work with 30 seconds of rest for two cycles. Cool down for 2 minutes. Increase the number of cycles as time allows and your fitness improves. The unlimited variations on the structure of HIIT workouts will keep them interesting!
How do I get started?
Before starting a HIIT training regimen, make an appointment with your healthcare provider. Check in about your chronic medical problems and any aches and pains or other symptoms that limit you. If you haven’t been exercising, he or she can work with you to establish a base fitness level for several weeks first to reduce the risk of injury. Start with just one HIIT session a week and then increase as you feel ready. Your healthcare provider can be a great resource for frequent check-ins for accountability and motivation.