Over the years, many different forms of exercise have become popular and the recent one is the high-intensity interval training (HIIT) workouts that do not require as much time, yet still produce remarkable health benefits.
In fact, a recent review has found that a form of HIIT workout called “low-volume HIIT” (which takes less than 15 minutes!) has all the benefits of higher volume interval workouts and more moderate, continuous exercise like running or cycling for 30-45 minutes. With lack of time being so often cited as the primary reason for not exercising more — discovering how to implement an effective exercise routine that can produce results in under 15 minutes would be good news indeed!
What are HIIT workouts?
In general, HIIT workouts are characterized by bouts of high intensity exercise interspersed with active or passive rest periods. So, for example, after a five minute warm-up you might do four intervals at a challenging pace for four minutes each (perhaps jogging or walking uphill on a treadmill), interspersed with three minutes of active rest like slower walking to catch your breath. It doesn’t have to be four minute intervals, they can be done for different lengths of time, but HIIT workouts always involve a “hard” work portion to get the heart rate and circulation to reach a certain threshold for adaptation, followed by a recovery period to catch your breath.
The benefits of low volume HIIT workouts
For decades, athletes and fitness enthusiasts have utilized this kind of hard interval training to improve their fitness and performance and reduce chronic disease risk. But a recent research review published in the Journal of Physiology titled “Low-volume high-intensity interval training for cardiometabolic health” has revealed that you can see benefits with even lower volumes of interval training than originally thought. How much lower? Try just one interval instead of four (as in my previous example).
The researchers looked at 11 different studies that used randomized trials of HIIT to track cardiometabolic outcomes (obesity, hypertension, type 2 diabetes and cardiovascular disease) and compare the results between low and high volumes of HIIT and more traditional forms of moderate aerobic exercise. While different low volume HIIT workouts were employed, like three intervals of three minutes or five intervals of two minutes (both with two minute active rests), as well as the aforementioned 1 x 4; the bottom line was that the total amount of time in active intervals was always less than 15 minutes (and usually less than 10). And they found that even such low volumes of HIIT as four minutes per session could bring significant improvements in blood pressure, oxygen usage, insulin sensitivity and weight management. Improvements similar to, and at times greater, than when compared to more traditional forms of moderate, continuous training — despite requiring less time commitment and lower energy expenditure.
How can low volume HIIT work?
Regardless of the style of low-volume HIIT workout, it is thought that the health improvements are caused by the intensity, or rate, that the heart and muscle cell structures are working — rather than the duration of the activity. The heart adapts and gets stronger because it is being asked to work harder (even for as little as four minutes) than it is used to — and the muscles energy stores are being depleted faster than is normal.
These energy stores, called glycogen in the muscles, are such an important fuel reserve that our body seeks to replenish it as a priority. HIIT workouts deplete muscle glycogen at an exponentially higher rate, causing an alarm reaction that prompts the body to increase the number and activity of mitochondria (the cells power plants) in our muscles to more effectively meet the energy demands of the high intensity activity. This in turn leads to improvements in fitness, metabolic function and health equal or greater than some much longer styles of exercise.
These results show that even a short workout can improve health. Current guidelines from the World Health Organization recommend adults perform 150-300 minutes of moderate intensity exercise, or 75-150 minutes of vigorous exercise a week. Yet, lack of time is the reason most often cited by people as the main barrier to exercise. Now that we see that low-volume HIIT, done just three times a week, has the potential to be more time efficient while offering similar improvements in health outcomes we can expect people to want to exercise less — but harder once they understand this research.
Give one of these low-volume, HIIT workouts a try in your next cardio workout — you’ll probably be in disbelief over how short the training is, yet how great you feel afterwards. You can improve your health in under 15 minutes a workout!
Thomas Morrison is the fitness coordinator at Bradley Wellness Center.