- The benefits of HIIT include burning calories, losing weight, and building muscle.
- HIIT can also help you lower blood pressure and blood sugar, while improving oxygen and blood flow.
- HIIT may also benefit brain health by improving mental health and memory.
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High-intensity interval training (HIIT) involves short, intense workouts. You give a series of exercises your full effort for short bursts, and follow it with a period of rest. While exercising with this type of maximum effort is difficult, it does wonders for your health.
"It's exercise after exercise with minimal rest," says personal trainer Stephen Navaretta, developer of The Tank Method, an exercise program based on body-weight exercises. "This gives your entire body, especially your heart and core, a great workout."
Here are 10 major health benefits of doing a HIIT workout.
1. HIIT can help you burn more calories
While you're doing a HIIT workout, you're burning about the same amount of calories as you would during a typical workout like running. However, you burn more calories after a HIIT workout than you do during a steady-state cardio exercise like running, where your heart rate remains relatively stable.
A 2019 study confirmed this by having a group of athletes do a HIIT workout and a steady-state run at two different times. Nine minutes after the exercises stopped, researchers found that the HIIT group was burning an average of 3 kilocalories per minute, compared with 2.8 kilocalories per minute after the steady-state run.
This phenomenon of burning calories after you stop exercising is called excess post-exercise oxygen consumption (EPOC). EPOC occurs when your body burns more calories healing the wear and tear from an intense workout. It's common with HIIT workouts because the exercise is so intense, and it has been linked to effective muscle growth.
2. HIIT may help you lose weight
Since HIIT burns more calories because of EPOC, it can be a more convenient way to help you lose weight, since you don't have to spend as much time working out.
A 2019 review analyzed 77 scientific studies. The review found that people who did HIIT workouts lost 28.5% more fat than people who did moderately-intense continuous exercise, like running.
"With HIIT, your heart rate stays up for the entire exercise, which is optimal for burning calories, making this an effective option for weight loss," Navaretta says.
3. HIIT builds many muscle groups
Most HIIT workouts involve many different movements. This allows you to work out different groups of muscle during the same workout — for example, a HIIT workout might have you do squats, push-ups, and burpees — which all target different muscles.
The intensity will also help build your muscles and improve their ability to keep working out. "This type of training boosts muscular endurance because the muscles don't get much rest," Navaretta says.
For example, a 2017 study found that a six-week HIIT program improved muscle power in men, measured by peak power output (PPO). Before the HIIT program, the mens' average absolute PPO was 799 watts, and after the workout it was 865 watts, an increase of about 8%.
Additionally, a 2017 study found that a 12-minute HIIT workout affected the muscles more than a 40-minute aerobic workout for overweight female teens. This was measured by tracking levels of irisin, a hormone released by the muscles in response to exercise.
4. HIIT improves oxygen and blood flow
Your heart pumps blood through the circulatory system in order to deliver oxygen and nutrients to your muscles. And research has found lots of evidence that HIIT workouts can support and even strengthen your circulatory system.
For example, a 2017 study split 26 school children into two groups: one group engaged in HIIT training, and one did a more traditional exercise regimen. The study lasted seven weeks. The HIIT group improved their cardiorespiratory capacity, or the ability of their heart and lungs to deliver oxygen to the body, more than the traditional exercise group, and also lost more fat.
In addition, a 2020 study found that just one HIIT session improved blood flow to the brain, saying "HIIT is an effective time-efficient alternative to long-duration lower-intensity exercise that offers similar vascular benefits."
Heart disease accounts for one-quarter of deaths in the US, and improving cardiovascular health can reduce your risk for heart disease, making HIIT workouts a great investment.
5. HIIT can help lower blood pressure
HIIT workouts can help lower blood pressure, a risk factor for heart disease.
A small 2017 study of men ages 56 to 67 who performed a HIIT workout five days a week for six weeks found that the group had an average reduction of about 5.5 mm/HG in blood pressure.
In addition, a 2017 study found that a session of HIIT resulted in a more immediate reduction in blood pressure than a session of steady-state cardio.
6. HIIT can help lower blood sugar
HIIT training can also help control blood sugar levels, particularly for people with diabetes.
A 2015 study found that after 8 weeks of HIIT, people with type 2 diabetes had improved control of their insulin levels and better pancreatic function.
In addition, a 2015 scientific review looked at studies where participants did HIIT regimens for less than two weeks. It found that HIIT helped people with and without diabetes better control their blood sugars than continuous-state workouts.
7. HIIT stimulates your metabolism
HIIT helps people to burn fat and carbohydrates within a short period of activity. People who do HIIT may also benefit from a revved up metabolism post-workout.
8. HIIT could improve sleep quality
Consistent HIIT workouts over a period of weeks could help improve your sleep quality and increase the time you spend sleeping.
A 2021 review showed that HIIT sessions of any type performed for more than 16 minutes per session for at least eight weeks can "significantly improve sleep quality" in adults. Additionally, doing HIIT workouts at least three times a week was associated with less time spent awake while in bed.
9. HIIT may improve mental health
It's well known that regular exercise and physical fitness is associated with better mental health and may even help specific illnesses like depression. Incorporating HIIT into your exercise routine could bring additional benefits:
- A 2020 review found that HIIT may help alleviate depression and that it could also possibly be beneficial for people with other mental illnesses, like schizophrenia-spectrum disorders.
- A 2019 meta-analysis of studies and randomized trials focusing on people with severe mental illness stated that HIIT improved depression more than moderate intensity continuous training (MCT), which includes prolonged aerobic exercises like jogging or swimming.
- A 2022 review of randomized clinical trials looked at the effect of HIIT on mental health in the general population, including those who are physically ill. Researchers said that HIIT "led to moderate improvements" in well-being, severity of depression, and perceived stress.
10. HIIT could help improve memory
Regular exercise not only bolsters general health, but it may also boost brain health. Scientists found that people who exercise have larger brain regions that are responsible for thinking and memory. Recent science shows that incorporating high-intensity intervals into workouts may be even more beneficial for brain health.
A small 2020 study looked at older sedentary adults who either did HIIT, MCT, or stretching to see how it affected their cognition. HIIT had the greatest effect on participants' memory performance.
HIIT workouts allow you to reap many health benefits without needing to go to the gym, or invest in equipment. Navaretta recommends doing a HIIT workout about 3 to 5 times per week.
"The average person is looking to be athletic and toned," Navaretta says. "HIIT training provides endless options for the types of movements that lead to that, as well as benefits like increased flexibility and endurance."