HIIT benefits: 68 benefits of high-intensity interval training

Posted on 06 August, 2021 by Nicholas Rizzo

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High intensity interval training is incredibly popular and is a great way to experience a wide range of exercise benefits. We spent 80+ hours analyzing over 220 studies on high-intensity interval training to provide a comprehensive review of the benefits of HIIT, broken down into the following sections:

High-intensity interval training for heart health

High-intensity interval training can be great for your heart. Research shows HIIT helps you have a healthier heart and cardiovascular health by reducing heart disease risk factors, blood pressure, and cholesterol. All together, the cardiovascular and metabolic benefits of HIIT actually reduces your risk of death by cardiovascular disease and is generally regarded as safe for those who are struggling with some forms of heart disease.

Heart

  • A healthy adult can achieve a maximum heart rate of 159 beats per minute after a HIIT workout.
  • HIIT was observed to reduce cardiovascular mortality by 5%.
  • 3.5 weeks of high-intensity interval workouts increased the left ventricular output by 9.1% in people with chronic heart failure.
  • The resting heart rate of CHF patients who did this type of training decreased by 5.3%.
  • High-intensity workout increases nitric oxide availability by 36% which improves blood circulation.
  • The relative risk of metabolic syndrome for people who suffered from myocardial infarction is 0.5 after 24 sessions of HIIT.

Blood pressure and Cholesterol

  • After 22 HIIT sessions, participants of a study showed a 23% decrease in their systolic blood pressure but no significant difference in their diastolic blood pressure. 
  • Triglycerides are reduced by 18% after 36 sessions of high-intensity interval workouts.
  • Overweight individuals who did HIIT for 12 weeks reduced their low density lipoproteins (LDL) by 20%.
  • The total cholesterol of obese people who did 12 weeks of high-intensity exercise programs was reduced by 18.4%.

Fat Loss

One of the main benefits of cardio that people look to is for help with fat loss. HIIT is one of the best forms of cardio for weight loss, that's because HIIT is designed to help the body burn calories in a shorter period compared to moderate-intensity continuous training. This form of exercise also increases metabolism after exercise. Bursts of exercise help people improve fat metabolism as well as tone their muscles.

  • A sprint interval training meta-analysis showed HIIT burns 36.34% more effective than moderate intensity continuous training while also spending significantly less time exercising. 
  • 1 minute of intense workouts burns about 12.62 calories or about 380 calories after 30 minutes.
  • Based on several studies, obese people experienced a weight loss of 3.6 kg after doing HIIT for 12 weeks.
  • Seniors who underwent 12 weeks of HIIT lost an average of 2.57 kg.
  • 10 weeks of HIIT can lead to a decrease in whole-body fat mass (BFkg) by 2 kg.
  • Waist circumference is reduced by 3 cm after 10 weeks of intense training.
  • 12 weeks of intense workout routines can reduce abdominal visceral fat by 19.5%.
  • 4 weeks of high-intensity interval workouts can reduce total body fat by 1.26%.
  • Fat mass is reduced by 1.38 kg by doing 4 weeks of high-intensity exercise.
  • BMI us reduced by 1.7% after 33 HIIT workouts.
  • The waist circumference of people with heart conditions was reduced by 7.4% after 33 sessions of HIIT.

Physical fitness, strength, muscle, and conditioning

HIIT improves cardiovascular health but it can also be used to build muscle and strength. Combining HIIT with the benefits of rowing machine workouts can help practitioners tone muscles, improve conditioning, strength, and overall physical fitness..

  • An increase of 0.8 kg in skeletal muscle mass was noticed in seniors who did HIIT workout for 12 weeks.
  • HIIT has been shown to stimulate the production of human growth hormone (HGH) by up to 450% for several hours post-exercise.
  • Six weeks of HIIT workouts can increase peak power output by an average of 8% compared to continuous training.
  • Some benefits of exercise like 8 weeks of high-intensity interval workouts increased upper body strength by 67.8%.
  • Leg muscle strength increased by 7.6% by doing HIIT 3 times a week for 8 weeks.
  • Multimodal HIIT (combination of strength exercises and HIIT) has been found more effective in increasing muscle strength than traditional HIIT; squat endurance increased by 280%, broad jump distance by 6%, deadlift by 18%, and leg press 27%, and squats 39%.
  • Master athletes who reduced their volume of exercise from 281 min/week to 4.5 min/week still increased their peak power output by 8%.
  • Heart disease patients who underwent 10 weeks of HIIT improved their oxygen consumption by 17.9%.
  • 12 weeks of HIIT workout results in an increase of respiratory muscle function by at least 43%.
  • Overweight and obese women who did HIIT 4 times a week for 5 weeks experienced a 9.1% increase in their VO2 peak levels. 
  • Seniors who did HIIT for 28 weeks saw a 26% improvement in their oxygen usage.

Diabetes prevention and management

One in 10 Americans have diabetes and 1 in 3 adults are at risk of having it. The lack of time is the top reason why people don’t exercise, which leads to developing diabetes. 

  • The blood sugar level of men with type 2 diabetes who did HIIT in the afternoon was 11.3% lower than those that did HIIT workouts in the morning.
  • HbA1c, or the average blood sugar in 2-3 months, is decreased by 0.27%
  • A 15% decrease in habitual insulin dosage was observed in people with type 1 diabetes mellitus who did a combination of intense exercise and strength training 3 times a week for 4 weeks.
  • After 8 weeks of high-intensity interval workouts, a 0.6% decrease in HbA1c was seen in people at risk of diabetes.
  • Extensive research done showed that HIIT workout significantly increased insulin sensitivity, meaning this type of workout improves the body's usage of insulin and absorption of sugar.

Mental and emotional health

Exercising prompts the production of endorphins in the body, a chemical that helps you manage pain and feel happy. Aside from that, increasing physical activity reduces stress hormones like adrenaline and cortisol. HIIT, despite it being fast-paced, also has the same effect.

  • Anxiety levels decreased by 14.6% in those who participated in an 8-week HIIT exercise program.
  • Depression caused by a health problem is decreased by 36. 8% in people who participated in an intense exercise program for 10 weeks.
  • Overweight people find short intense workout routines enjoyable as evidenced by a 93.4% adherence rate.
  • Doing HIIT workout 2 to 3 days a week for 8 weeks increased workplace productivity by 7.2%.
  • 8 weeks of doing high-intensity interval workouts increased motivation by 4.9%.
  • Workplace well-being increased by 2.2% in those who joined the 8-week HIIT program.
  • Estradiol, a hormone linked to depression, among other health issues, was decreased by 50.3% in women who did HIIT 4 times a week, for 5 weeks.

Bone and joint health

Bone brittleness can lead to serious injuries but can be prevented with HIIT. According to several studies, high-impact exercises like jumping rope benefits bone density of the back and the lower limbs.

  • Older adults who did 10 weeks of HIIT decreased the progression of rheumatoid arthritis by 38%.
  • People with rheumatoid arthritis experience a 55.8% decrease in swollen joints after 10 weeks of HIIT exercise.
  • HIIT exercise duration of 10 weeks decreased pain level caused by rheumatoid arthritis by 29.3%.
  • Post-menopausal women who did aquatic HIIT for 24 weeks increased bone density by 6-16%.

Cancer

Aerobic exercise, from walking to riding a bike have been known to decrease the risk of certain cancers, but not enough study has been done in relation to HIIT. However, it has been discovered that cancer patients may benefit from doing HIIT.

  • A study of breast cancer patients undergoing chemo determined that those who add resistance and HIIT to their exercise routine for 16 weeks reduced cancer-related fatigue by 8.6%.
  • Women with breast cancer who undergo chemotherapy usually gain 5 kg, but those who did HIIT 2 days per week for 16 weeks did not gain weight.
  • Another benefit of this type of exercise is that it was found to increase the pressure pain threshold of cancer survivors.

Quality of life

HIIT, like other exercises, improves the various functions of the body. These improvements have significant positive effects on the overall well-being of a person, which helps them better enjoy their lives.

  • 12 weeks of high-intensity intervals is attributed to the reduction of all-cause mortality by 8%.
  • After 8 weeks of HIIT, participants in a study noted that they added 0.76 hours of sleep during weekdays.
  • People with sleep apnea who participated in 12 weeks of HIIT reduced their episodes by 7.5 events per hour.

FAQs

What is high-intensity interval training?

HIIT stands for high-intensity interval training. It is a type of exercise that combines bursts of movements of varying intensity to achieve maximum calorie burn during and after the activity.

Is HIIT for everyone?

Yes, regardless of your current fitness level, there's a HIIT program that will cater to your needs. The level of intensity of HIIT usually doesn't get affected if you're a newbie. But you can adjust the frequency of your workouts so your body will have enough period of rest for your body to recover. You can also alter your workout duration to fit your schedule and your body's capacity to train.

Will HIIT burn fat?

Yes, several studies have shown that HIIT can decrease total body fat by at least 1.26% after 4 weeks of training. Meanwhile, abdominal fat is reduced by 19.5% in 12 weeks of HIIT.

Can you lose weight doing HIIT?

Yes and no. As mentioned earlier, you burn calories when you do HIIT. But because HIIT can build muscles, the fat you are burning away is being replaced with toned muscles. So you might not see the numbers on the scale go down, but your clothes will fit better.

Is doing HIIT once a week effective?

Studies have shown that doing an intense workout routine once a week, for 23 minutes, during an 8-week period can improve cardiovascular health and reduce the risk for heart diseases.

What is the HIIT afterburn?

Afterburn is when your body still burns calories 24 hours after exercise. According to research, doing high-intensity intervals results in increased metabolism, which also means increased oxygen consumption as the body recovers from all the ATP or energy fuel used up. What this means is, if your fitness goal is to burn more calories, then HIIT is an effective workout to help you achieve it.

Can you do HIIT if you have COPD or asthma?

Yes, studies have shown that a high-intensity training method can help reduce shortness of breath when doing daily activities. Intense training programs increase your lung capacity and total oxygen consumption.

Are there any downsides to HIIT?

Yes. Because of the fast movements and high-impact nature of some of the moves, some people sustain injuries in their knees and ankles, trunk, and even upper limbs. To reduce the risk for injuries, experts suggest undergoing neuromuscular training and pre-strengthening programs.

Can people in cardiac recovery do HIIT?

People who are in cardiac recovery can still do HIIT. Studies have shown that short-duration high-intensity intervals can help with improving cardio health, reducing risks of another attack, and enhance overall well-being.

Can post-stroke patients benefit from doing HIIT?

Yes and based on various studies, HIIT can help in post-stroke rehabilitation. Altering your exercise habits by doing HIIT 3 times a week for 4 weeks has increased the gait speed, cadence, and stride length of post-stroke patients.

Does blood glucose rise after HIIT?

Yes, but only a little. The short but high-impact workout routine causes the liver to release more glycogen as it anticipates the need for more energy usage. The upside is since your body still burns calories 24 hours after exercise, your blood sugar level also decreases.

Conclusion

Working out 5 or more times a week at a moderate pace has been proven to be effective in improving a person’s health, not to mention losing weight and trimming inches off the waist. However, not everyone has the time to exercise every day.

The short and fast-paced nature of HIIT makes it appealing for people who lead very busy lives. They can reap the health benefits of a moderate-intensity continuous training program in just a few minutes.

About RunRepeat

RunRepeat provides visitors with the data they need before making their next shoe purchase. We have collected user and expert reviews on top of the shoe specs and features.

HIIT is unlike regular exercise as most moves require quick movements and high-impact lower body exercises. You need HIIT shoes with reliable traction while also providing excellent cushioning.

Some Nike HIIT shoes are equipped with air cushioning that is effective in reducing impact as well as delivering bounce in each step. Reebok HIIT trainers offer uncompromised flexibility under the toe, which is perfect for burpees, planks, and mountain climbers. Meanwhile, if you want a firm platform, check out Under Armour HIIT shoes.

Use of content

  • If you want to know more about this article, reach out to Nick Rizzo at nick@runrepeat.com. He’d be happy to answer questions or give an interview.
  • Data on this analysis is free to use on any web coverage of the same topic or related articles. We only request that you link back to this original source.

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Author
Nicholas Rizzo
Nicholas Rizzo

Nick combines 10+ years of experience in the health and fitness industry and a background in the sciences in his role as the Fitness Research Director. During his competitive powerlifting years his PRs have him sitting in the top 2% of bench presses (395 lbs), top 3% of squats (485 lbs) and top 6% of deadlifts (515 lbs) for his weight and age. His work has been featured on Bodybuilding.com, LiveStrong, Healthline, WebMD, WashingtonPost, and many more. Along the way, collaborating with industry leaders like Michael Yessis, Mark Rippetoe, Carlo Buzzichelli, Dave Tate, Ray Williams, and Joel Seedman.