HIIT stands for high intensity interval training and is an advanced type of cardio workout that involves alternating between periods of energetic exercise and periods of active or passive rest.
From influencers and journalists to personal trainers and researchers, it seems the virtues of HIIT are extolled far and wide. So with more acolytes than you can shake a stick at, does this celebrated wunderkind live up to the rhapsodizing or is it just a load of hot air?
The Benefits of HIIT
It’s rare, but research shows that HIIT is one of the few trends that really does live up to the hype. Here are some of its many benefits.
1. It’s Quick & Efficient
HIIT’s unique selling point is it’s brevity. Because of the intensity (difficulty) of HIIT, workouts are generally quite short. This is in sharp contrast to standard run-of-the-mill cardio workouts that will probably run close to an hour. HIIT sessions tend to last 30 minutes or less. So if lack of time is an issue, HIIT might just be the solution. Short and sweet, this workout fits into any schedule.
HIIT offers similar and sometimes better results than endurance training (exercising at moderate intensity at a steady pace – aka normal cardio) in less time.12 The variety that makes HIIT so interesting, is also what makes it so effective.
2. HIIT Can Help You Lose Weight
HIIT achieves similar weight loss as moderate-intensity exercise, but takes about half the time to burn the same amount of calories.34 Furthermore, HIIT is at least as effective at reducing body fat, including belly fat.5678910
Research shows that HIIT improves the body’s ability to burn fat, increases metabolism post-workout so you continue to burn more calories (the “afterburn effect”), decreases appetite, lowers insulin resistance, and improves blood sugar control. 1112131415161718
3. It May Build Muscle
HIIT doesn’t just do the same in less time. Whereas regular endurance-based exercise doesn’t build muscle, HIIT can increase muscle mass while simultaneously reducing body fat.192021
Regular cardio works the kind of muscle fibers that have little capacity to grow in strength or size. On the other hand, HIIT targets the type of muscle fibres (called fast-twitch) that can lead to increases in muscle mass, strength, and power – much like lifting weights would do (but not quite as much).22232425
4. HIIT Boosts Cardiovascular Fitness
The go-to-method for increasing cardiovascular fitness has always been endurance training such as jogging. But research shows that HIIT can boost cardiorespiratory fitness (VO2max) faster and at least as much as endurance exercise.26272829 Plus, unlike endurance training HIIT increases anaerobic fitness (speed and power) too.30
The improvements in endurance can be quite staggering. In one study, participants doubled the amount of time they could exercise continuously at high-intensity after just two weeks and six HIIT workouts.31
5. It Can Improve Cardiovascular Health
HIIT improves heart structure and function, as well as the health of blood vessels. It reduces blood pressure, resting heart rate, and blood cholesterol.323334 Research suggests that HIIT may be better than steady-state, moderate-intensity workouts at improving cardiovascular health.35
HIIT appears to be more effective in people at higher risk of cardiovascular disease and type-2 diabetes, who tend to reap even greater cardiovascular benefits than healthy people.36373839 In fact, some rehabilitation programs for people who have had a heart attack employ specially adapted HIIT workouts.40
6. HIIT Can Increase Metabolic Health
HIIT improves type-2 diabetes, and also reduces the risk of suffering with diabetes. It lowers insulin resistance, which is a precursor to type-2 diabetes, and improves blood sugar control.414243
HIIT significantly improves metabolic syndrome (a constellation of cardiovascular risk factors that include high blood pressure, high blood sugar, excess belly fat, and high cholesterol) – more so than traditional cardio.44
7. It Can Improve Quality of Life
- Reduces pain.48
- Improves cognitive function49
- Better sleep quality. 50
- Positive impact on mental health.515253
- Increases energy levels, by boosting the function of mitochondria (our body’s energy factory).5455
8. HIIT is Fun
Short, sharp. Easy, hard. You have to stay on the ball. The one thing HIIT is not, is monotonous. While steady-state cardio allows you to zone out (thoughts flowing, feeling zen), HIIT allows you to let it rip, getting you pumped and your adrenalin flowing. Indeed, research suggests that HIIT may be more enjoyable.565758
How to Get Started
HIIT has many health benefits. Still, because HIIT is an intense form of exercise, it’s important you do this type of workout once you have developed a basic level of fitness. Build up steadily with a few weeks of regular moderate exercise and gradually increase the intensity. Then simply choose an HIIT workout to suit your fitness level and goals, and be prepared to get your sweat on!
If you’re doing a workout that includes strength exercises, be sure you are able to execute the moves with perfect form before doing them in an HIIT workout.
Before starting high-intensity exercise, speak with your doctor, especially if you have a pre-existing medical condition. They might recommend a workout that is tailored to your needs, e.g. lower impact exercises if you have joint problems.