High-Intensity Interval Training, or HIIT, has become a popular workout trend in recent years, and for good reason. This style of training involves short, intense bursts of exercise followed by periods of rest or active recovery. HIIT offers a way to get the most out of your workout in the least amount of time. You can tailor it to fit your fitness level and goals, and you don’t need a lot of equipment or even a gym membership. Plus, the short bursts of intense exercise get your heart rate up and burn calories quickly.
How did it get started? In the 1960s and 1970s, Dr. Izumi Tabata, a Japanese researcher, began studying the effects of interval training on athletes. He discovered that short bursts of high-intensity exercise followed by periods of rest were more effective for improving athletic performance than steady-state cardio. This work laid the foundation for the modern HIIT workouts we see today.
While HIIT is known for its ability to burn fat and improve cardiovascular fitness, scientists are still exploring how it leads to improvements in fitness and heart health. In this article, we’ll explore the science behind HIIT and how it improves cardiovascular fitness and burns fat.
HIIT Boosts Oxygen Consumption
The primary benefit of HIIT is it increases your heart rate and oxygen consumption, which in turn leads to improved cardiovascular fitness. During a HIIT workout, your heart rate rises rapidly as your body works hard to meet the demands of intense exercise. This increase in heart rate leads to a sharply elevated oxygen demand, forcing your heart and lungs to work harder. Over time, this increased cardiovascular activity leads to improved cardiovascular fitness and endurance.
Research shows HIIT programs can yield similar cardiovascular improvements when compared to more traditional, steady-state exercise programs while requiring less time. HIIT improves cardiovascular health by promoting changes at the cellular level. These changes include:
- Increased stroke volume: HIIT increases the heart’s stroke volume, which is the amount of blood the heart pumps with each beat. This increased stroke volume can help to improve cardiovascular health and reduce the risk of heart disease.
- Increased blood flow: HIIT boosts blood flow, which means that more oxygen and nutrients are delivered to the cells and tissues in the body.
- Increased blood vessel diameter: HIIT increases the diameter of blood vessels, which improves blood flow and helps lower blood pressure.
- Improved heart rate variability: HIIT improves heart rate variability, which is a measure of the heart’s ability to respond to changes in the body’s needs. Greater heart rate variability can help to reduce the risk of heart disease.
- Increased production of nitric oxide: HIIT has been shown to increase the production of nitric oxide, which is a molecule that helps to regulate blood flow, lower blood pressure, and reduce the risk of abnormal blood clotting.
High-Intensity Interval Training is a Fat Burner Too
Along with improving cardiovascular fitness, HIIT is a fat burner, which is the reason many people do it. The intense nature of HIIT workouts causes your body to continue burning calories long after the workout is over. This is known as the “afterburn effect,” and it can help you to continue burning fat for hours after a sweaty HIIT session is over.
HIIT can burn more calories in a shorter period due to the high intensity of the workout. Research also suggests it’s more effective at reducing abdominal fat than other types of exercise. A study from the Journal of Obesity found that HIIT may be more effective than regular steady-state exercise such as walking and jogging at a moderate intensity for fat loss.
One of the key reasons HIIT is so effective for burning fat is that it increases your metabolism. During a HIIT workout, your body works hard to meet the demands of intense exercise, causing your metabolism to increase. This increased metabolism helps to burn more calories and fat, both during the workout and after it’s over.
During HIIT, the high-intensity intervals result in greater physical and mental stress on the body, leading to a larger release of adrenaline compared to steady-state exercise. Studies show epinephrine and norepinephrine levels are elevated 6.2 to 14.5 times greater than baseline during HIIT workouts. The increased adrenaline release not only elevated resting metabolism: it boosts energy levels, improves mood, and increases focus and alertness.
Along with its fat-burning benefits, HIIT improves muscle endurance. The intense nature of HIIT workouts challenges your muscles to work harder, leading to improved endurance and strength over time. This is particularly beneficial for athletes who need to maintain their strength and endurance during long periods of intense exercise.
Start Slow
It’s worth noting that HIIT is not for everyone. This style of training is intense, and it requires a high level of motivation and commitment. If you’re new to exercise or haven’t been active in a while, start slowly and work your way up to more intense HIIT workouts. Listen to your body and stop if you experience pain or discomfort.
If you’re interested, there are many different HIIT workouts you can try. Some popular HIIT workouts include circuit training, Tabata, and interval runs. When choosing a HIIT workout, consider your fitness level and personal preferences. Also, ensure you have a supportive pair of exercise shoes and warm up thoroughly before starting your workout.
Conclusion
HIIT is a highly effective way to improve cardiovascular fitness and burn fat. The intense nature of HIIT workouts leads to increased heart rate and oxygen consumption, which contributes to cardiovascular fitness. In addition, the “afterburn effect” of HIIT workouts helps to burn fat for hours after the workout is over. If you’re interested in trying HIIT, make sure to start slowly, listen to your body, and choose a workout that’s right for you. With a commitment to HIIT, you can enjoy the many benefits this style of training has to offer.
References:
The Workout Debate: Experts Weigh in on Cardio VS. HIIT. (2023). Retrieved 10 February 2023, from https://www.pennmedicine.org/news/news-blog/2018/march/the-workout-debate-experts-weigh-in-on-cardio-vs-hiit
Foster C, Farland CV, Guidotti F, Harbin M, Roberts B, Schuette J, Tuuri A, Doberstein ST, Porcari JP. The Effects of High-Intensity Interval Training vs Steady State Training on Aerobic and Anaerobic Capacity. J Sports Sci Med. 2015 Nov 24;14(4):747-55. PMID: 26664271; PMCID: PMC4657417.
High-intensity interval training for health benefits and care of cardiac diseases – The key to an efficient exercise protocol. (2023). Retrieved 10 February 2023, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6763680/
Boutcher SH. High-intensity intermittent exercise and fat loss. J Obes. 2011;2011:868305. doi: 10.1155/2011/868305. Epub 2010 Nov 24. PMID: 21113312; PMCID: PMC2991639.
Metabolic Effects of HIIT. (2023). Retrieved 10 February 2023, from https://www.unm.edu/~lkravitz/Article%20folder/metabolicEffectsHIIT.html
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