Calories Burned From High-Intensity Interval Training

High-intensity interval training (HIIT) involves short bouts of very vigorous cardio or weightlifting with short rests or lower-intensity exercise. Considered a time-efficient workout, HIIT calories burned can be equal to or greater than that of a longer, low-intensity workout.

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In a November/December 2019 survey from the American College of Sports Medicine's ‌Health & Fitness Journal‌ on the 2020 fitness trends, health and fitness professionals from all four sectors of the industry (corporate, clinical, community and commercial) named HIIT the second biggest trend after wearable technology.

Found in boutique gyms around the world and touted in fitness publications, HIIT has become quite the phenomenon for its efficient workout strategy and ability to burn calories quickly.

Determining the calories burned in a HIIT workout session is challenging, though, and requires consideration of a number of factors: the type of exercise you do, your intensity level and your weight. But beyond this, research says that a HIIT workout does burn more calories than other workout regimens.

A March 2015 study from the ‌Journal of Strength and Conditioning Research‌ found that a 30-minute HIIT session can burn 25 to 30 percent more calories than a 30-minute steady-state exercise of cycling, using a treadmill or weightlifting.

If you take the Harvard Health Publishing's calories burned per 30 minutes of cycling, a HIIT workout for people of three different weights can compare as follows:

• ‌125-pound person:‌
  A steady-state 30-minute cycling session at 14 to 15.9 miles per hour: 300 calories burned.
  A HIIT cycling session: up to 390 calories burned.
  A steady-state 30-minute cycling session at 16 to 19 miles per hour: 360 calories burned.
  A HIIT cycling session: up to 468 calories burned.
  
  
• ‌155-pound person:‌
  A steady-state 30-minute cycling session at 14 to 15.9 miles per hour: 372 calories burned.
  A HIIT cycling session: up to 484 calories burned.
  A steady-state 30-minute cycling session at 16 to 19 miles per hour: 446 calories burned.
  A HIIT cycling session: 557.5 calories burned.
  
  
• ‌185-pound person:‌
  A steady-state 30-minute cycling session at 14 to 15.9 miles per hour: 444 calories burned.
  A HIIT cycling session: up to 577 calories burned.
  A steady-state 30-minute cycling session at 16 to 19 miles per hour: 533 calories burned.
  A HIIT cycling session: 692.9 calories burned.

You burn a higher number of calories in HIIT due to oxygen uptakes. The American Council on Exercise (ACE) says that your body burns calories at a rate of 5 calories per liter of oxygen consumed. Because in a HIIT workout you significantly increase the oxygen demands, this increases your total caloric expenditure both during and after a workout.

This anaerobic interval training also uses the body's reserves of energy, which elevates your metabolism and allows you to continue to burn calories for hours after the workout.

HIIT can also burn more calories and be easier on both your mind and body. The ACE says that this type of training is easier to sustain than a long, steady-state exercise. From both a mental and physiological perspective, your body can maintain a high-level intensity for a shorter period of time than exercise lasting longer than 30 minutes, and burn more calories.

According to the ACE, you should only perform a HIIT workout two to three times a week with 48 hours between each session for a full recovery from the stress you place on your body. You can still exercise the day after a HIIT workout, but your exercises should be low or moderate in intensity level and use different muscle groups than what you used in your high-intensity workout.

If you are training for an endurance event, such as a long-distance running race, you still need your high-volume workouts, such as long runs. HIIT workouts can actually come in handy during these training times when you simply want to skip exercise. You can do a short, intense workout and be done.

In addition, the University of Pennsylvania's School of Medicine says that you should have a foundation of moderate intensity exercise for several weeks before starting any HIIT program, regardless of whether you are young and active or older. This is because the fast exercise can make you vulnerable to injuries, such as sprains and strains.

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Following a HIIT training routine can allow for efficient and effective workouts. Other benefits of such a workout include the following:

• ‌Saves time.‌ You don't need to spend hours burning calories in a cardio or weightlifting session. A study from the April 2016 issue of ‌PLOS One‌, found that a cardio group had to log five times the amount of time in the gym as a HIIT group doing nothing more than a 10-minute interval workout that included three sets of 20-second sprints with two minutes of an easy recovery pace in between.
  
  At the end of 12 weeks of workouts, both the cardio and HIIT groups increased their VO2 max by 19 percent and lost a similar amount of body fat — but the HIIT group did a whole lot less work in a significantly less amount of time.

• ‌Increases cardiovascular fitness in patients with metabolic diseases.‌ In an August 2014 study from the ‌British Journal of Sports Medicine‌, researchers found that in patients with lifestyle-induced chronic diseases, such as diabetes, hypertension, heart failure and obesity, HIIT increased cardiorespiratory fitness at a 9.1 percent greater rate when compared to moderate-intensity continuous training.

• ‌Produces physiological gains.‌ According to the ACE, you can improve your stroke volume for running and cycling, improve your oxidative capacity for muscle and enhance your aerobic efficiency with HIIT.

• ‌Improves testosterone levels.‌ The University of Pennsylvania's School of Medicine says that HIIT can increase testosterone, which is shown to decrease with steady-state aerobic exercise.
  
  
• ‌Increases your motivation.‌ The University of Pennsylvania's School of Medicine suggests that you might be more apt to complete a 20- to 30-minute workout at the gym when compared to a 60-minute run on a treadmill.
  

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