Saturday, November 10, 2018

The Calorie-Burning Science Behind Sprint Interval Training

Interval training has become more and more popular in recent years, and for good reason. People are busier, and they want to make the most out of their time. Productivity is on everyone’s agenda, and that includes fitness optimization. 

Enter interval training, the king of efficiency when it comes to workouts. 


It's a form of physical training which alternates short bursts of high-intensity activity with longer periods of low-intensity exercise. Let's say you are a runner. In this case, interval training would mean including short sprints in between periods of running at a lower recovery pace. 

It’s an intense form of exercise, which means a workout will be a lot shorter than cardio. You would only need (and be able to do) around 20 minutes workouts. 


Any type of exercise has its own advantages, and interval training is no exception. For starters, it leads to building fitness and improving performance faster. 

Interval training combines aerobic and anaerobic exercise. Aerobic activity is the lighter exercise (jogging, walking, dancing – you get it), while anaerobic exercises are the higher intensity activities that you can’t sustain for long (i.e. sprinting). Training the anaerobic system makes the body adapt over time and increase endurance for intense exercise. 

Also, by repeatedly raising and lowering the heart rate, the cardiovascular system is strengthened faster than with other forms of workouts. In comparison, cardio keeps the heart rate relatively constant, and while that still improves its overall health, it doesn’t train it to adapt to fast changes. 


The main reason for the popularity of interval training is that it’s an excellent and time-efficient way of burning calories [1, 2]. Depending on the exercise and intensity level, you could burn more calories by doing 30 minutes of interval training than from 1 hour of cardio. 

How does that work? EPOC: Exercise Post Oxygen Consumption, a response triggered by intense, anaerobic activity. EPOC causes the organism to later consume a larger amount of oxygen in order to recover. Because of its effect, the body simply burns more calories while resting, after completing a workout. 

With cardio, calories are mainly burnt during the actual exercise, and the EPOC effect is minimal. Studies show that intense training generates a much stronger EPOC effect and a higher energy expenditure [3, 4] High-intensity workouts can activate the calorie burning effect of EPOC for up to 38 hours [5].

It is hard to calculate how many calories you burn from EPOC, and studies show different results. However, calorie burning also varies due to factors such as age, weight, or gender. 

It still makes sense to incorporate interval training into your exercise program. Even if we go by lower figures, you would still be burning calories after you finish exercising, while doing nothing. If maximizing time efficiency is a priority, interval training will enable you to make the most out of it. 


While it used to be mostly for high-level athletes, nowadays interval training is popular for everyone. 

What’s great is that you can incorporate it into different activities, whether it’s running, cycling, elliptical machine or whatever other exercise you like. You can also adapt it to your level of fitness. 

If you have a good fitness level, you might want an intense, structured training, such as high-intensity interval training (HIIT). The higher the intensity, the more calories you’ll burn [6], so HIIT is considered the best fat-burning option. You could add 30 minute HIIT workouts (such as a high-intensity spinning class, or sprints) in your fitness program. 

HIIT is not recommended for beginners, as it could cause injuries. However, novices can incorporate low-intensity interval training into their routine. Scientists have found that low-intensity training can be just as effective as higher intensity activity [7], and it will allow you to exercise for longer to maximize fat burn. 

If you enjoy going for walks, next time you can add short periods of fast walking or light jogging. You’ll save some time, and burn more calories. Win-win.  Interval training is a great form of exercise for burning fat, due to the elevated metabolism which allows you to burn calories while resting. 
But ultimately, the best exercise is the one you enjoy, because that’s what you’re going to stick to. For those who enjoy interval training, that’s awesome.  But if you absolutely love running for an hour at a steady pace, you will probably see more results this way than by forcing yourself to do HIIT if you don’t like it. 

While burning calories can be optimized through interval training, diet still plays the biggest role in losing weight. To make the most out of your exercise, make sure to also eat healthy, and cut junk food. 

Studies cited: 

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