What if you could exercise for less than one hour per week and burn more fat and gain more health benefits than clocking in your daily long, grueling workout? Sounds too good to be true, right? Lucky for all busy or exercise-phobic people out there, the latest research begs to differ. This seemingly magic bullet of a workout is technically termed ‘High-Intensity Interval Training’ (HIIT for short), and has been well-known in the competitive athlete circuit since the 1970s. Recent studies show that HIIT may be one of the most effective and time-efficient ways for people to burn fat, increase fitness levels, and increase insulin sensitivity.
What exactly is HIIT?
HIIT workouts all follow the basic principle of alternating short bursts of very intense anaerobic exercise (such as sprinting or pushups) with intervals of less intense recovery periods. These workouts tend to be brief and efficient, usually ranging in length from about 6-30 minutes total, and are performed about three days per week. This means that in as little as 20 minutes total per week you can significantly improve your health and may decrease your risks for developing diabetes, cardiovascular disease, and obesity.
What does a typical HIIT workout look like?
Here is a sample workout done on an exercise bike:
- 2 minutes of gentle cycling to warm up
- 20 second interval of cycling as fast as you can
- 1 minute interval of gentle cycling
- Repeat fast/gentle cycling intervals 2-3 more times
- 2 minutes of gentle cycling to cool down
- End workout!
- Repeat 3 times per week.
That’s it! Less than 10 minutes of exercise, three times per week, for a total of about 30 minutes per week. There are many forms of HIIT routines available, and there is no clear research yet showing which are better than others. Here’s a helpful infographic to look at when deciding what kind of HIIT workout is right for you.
Some HIIT routines incorporate more muscle-building resistance training. One example is ‘The Scientific 7-Minute Workout“, published in the New York Times last May, which outlines a series of 12 exercises that can be done at home using simply a wall, chair, and your own body weight for resistance. This routine is based on research done at the Human Performance Institute, and makes HIIT even more easily doable for busy people in their own home.
How does HIIT work?
While it may seem counterintuitive that exercising for shorter amounts of time can burn more fat than exercising longer, high intensity exercise increases levels of catecholamines (hormones released from the adrenal glands) and Human Growth Hormone (HGH), which greatly increase fat metabolism and make these shorter workouts very effective. High-intensity exercise also has a big influence on insulin sensitivity and blood glucose. One research study showed that in patients with type 2 diabetes, just one high-intensity interval training session improved blood glucose regulation for 24 hours. Other studies have shown that the metabolic benefits of regular HIIT training last for up to 3 days after a workout. HIIT training may also have effects on a genetic level, causing an increase of lipolytic (fat-busting) enzymes following a workout.
Who should try HIIT?
While most people can benefit from some form of HIIT, this kind of exercise is taxing on the body and not without risks. It is important to understand proper form and technique when doing many of the intense exercises that may be part of a HIIT program, as this type of exercise carries risk of injury when done improperly. People who are overweight, obese or sedentary, those with previous injuries, the elderly, and those with certain chronic illnesses, particularly cardiovascular disease, need to take caution and consult a physician before jumping into an intense exercise program.
While the evidence supporting HIIT as a beneficial form of exercise is growing, we should acknowledge that fat burning, fitness level, and insulin resistance are just a few of the many benefits of exercise. HIIT may not be the best way to increase your total strength, specific endurance, and other gains that can be received from other types of workouts. Activities like going for a walk outside or taking a yoga class may not burn as much fat as HIIT, but can boost your mood, decrease your stress levels, and increase your overall well-being, and should not be sacrificed in order to solely focus on HIIT exercises. We should also acknowledge that HIIT and other kinds of exercise are only one component of chronic disease prevention and healthy lifestyle. A balanced diet, restful sleep, and managing stress are also vitally important to preventing chronic diseases such as diabetes, so don’t forget about these factors on your pursuit to optimal health.
By Niki Rarig NCNM Naturopathic Medicine Program and School of Classical Chinese Medicine, Edited by Dr Elise Schroeder
- Adams OP. The impact of brief high-intensity exercise on blood glucose levels. Diabetes, Metabolic Syndrome, and Obesity: Targets and Therapy. Feb 26, 2013; 2013 (6): 113-122.
- Boutcher SH. High-Intensity Intermittent Exercise and Fat Loss. Journal of Obesity. 2011; 2011 (868305): 1-10.
- The Complete Guide to Interval Training. The Greatest Team. September 13, 2012. Available at: http://greatist.com/fitness/complete-guide-interval-training-infographic. Accessed October 28, 2013.
- Klika B and Jordan C. High-Intensity Circuit Training Using Body Weight: Maximal Results with Minimal Investment. ACSM Health and Fitness Journal. May/June 2013; 17(3): 8-13.
- Paddock C. How to Get Fit With 3 Minutes of Exercise a Week: BBC Doc Tries “HIT.” Medical News Today. March 6, 2012. Available at: http://www.medicalnewstoday.com/articles/242498.php. Accessed October 28, 2013.
- Reynolds G. The Scientific 7-Minute Workout. The New York Times. May 9, 2013. Available at: http://well.blogs.nytimes.com/2013/05/09/the-scientific-7-minute-workout/?_r=2. Accessed October 28, 2013.