Guide to HIIT: definition, science, benefits, and HIIT exercises

High-intensity interval training (HIIT workouts) is becoming increasingly popular among fitness enthusiasts. This training style is a form of interval training that alternates high-intensity exercises with less intense exercises or rest periods for recovery. The set is repeated for a specific number of sequences or until the exercise performer is too tired to continue. (Hiitsquadng)

Although HIIT has surged in popularity, many workout enthusiasts do not understand the science behind the training or the full extent of its benefits. This article discusses the science of HIIT, the benefits, and simple workouts you can perform anywhere, read on.

The science of High-intensity interval training

HIIT explores the effect of high-intensity exercise on the body to produce maximal calorie burn within the shortest period. The internal process starts with the build-up of lactic acid in the muscles during training. This triggers the body’s metabolism to release oxygen to counteract the excess lactic acid in the body. The outcome is the conversion of calories (energy) stored as body fat into energy. 

High-intensity interval training involves aerobic and anaerobic activity; as a result, it improves aerobic and anaerobic endurance. HIIT has many benefits, and science has proven some of these benefits, while some are still being researched.

Benefits of HIIT workout

You burn more calories performing a HIIT workout than in any exercise

High-intensity interval training is the most efficient way to exercise. Research has shown that HIIT burns more calories than other exercises performed within the same timeframe.

The science behind HIIT’s effective calorie burn is fascinating. High-intensity interval training causes the muscles in the body to build lactic acid, which leads to an oxygen deficit. To reverse the deficit, stored oxygen in the body is released into the body.

While oxygen is being released into the body, fat stores are being converted to energy through the same metabolic process.

In the body, excess calories are stored as fat cells. The amount of fat in the body determines the body type, whether thin (ectomorph), thick (mesomorph), or obese (endomorph).

Your metabolic rate is higher after a HIIT workout.

HIIT workout increases the body’s metabolic process to a maximal level during an exercise. Even after a HIIT workout, it takes 16-24 hours for the body to replace the used oxygen reserves. This makes HIIT workout capable of creating prolonged after workout effects.

A scientific study discovered that two minutes of HIIT in the form of sprint increases the body’s metabolic rate for over 24-hours as much as 30 minutes running.

It produces better results in less time.

One of the standout benefits of HIIT is that it produces the same or even more health benefits compared to other forms of training.

HIIT alternates high-intensity workout with periods of rest or low-intensity exercises to aid recovery.

A standard HIIT workout can be performed within 20 minutes. This makes High-intensity interval training suitable for all ages and anyone on the clock. You can perform a HIIT workout before taking your bath in the morning or an evening shower.

It can help you lose weight.

A study showed that people who engaged in HIIT three times a week for 20 minutes lost 2kg body fat after 12 weeks. This result was obtained without any dietary changes.

The principle by which HIIT increases metabolism to boost calorie burn has been explained earlier. Weight (fat) loss is an aftereffect of calorie consumption. However, losing weight requires a more conscious effort. Since weight loss only occurs when calorie expended is higher than calories consumed.

HIIT increases the use of stored calories during and after a workout. This effect can only lead to significant weight loss when the calorie expended is higher than calories consumed after a workout.

That said, it is worth noting that the weight loss benefit of HIIT is more evident in people who are obese or overweight.

It can increase Oxygen consumption

High-intensity interval training has been proven to increase Oxygen consumption by as much as 9%. This result is obtained in less time compared to other forms of exercise.

Basically, improved oxygen consumption increases your muscle performance, recovery rate after exercise or strenuous activity, and improves your endurance/stamina – you won’t run out of breath quickly.

HIIT can help blood pressure and heart rate.

Research into the benefits of HIIT showed some health benefits, including positive blood pressure and heart rate control.

A study discovered that HIIT could reduce heart rate and blood pressure in overweight or obese individuals who are susceptible to heart diseases.

Another study discovered that eight weeks of HIIT on a stationary bike could decrease blood pressure as much as other forms of traditional training.

How to perform HIIT workouts

HIIT workouts can be simple or complex exercises that are performed at maximal intensity for a short time. Performing HIIT exercise should be quite easy for people who exercise regularly.

On the other hand, individuals who do not exercise regularly or have never exercised may find a HIIT workout difficult. Most newbies struggle with sustaining the intensity required for a HIIT exercise.

For beginners, the rule of thumb is to progressively increase the intensity of their training as they get more comfortable with the routine. As a newbie, having the proper form while exercising is more important than exercising at a high intensity.

After learning the proper form for each exercise, you should focus on intensity. HIIT is all about intensity, so focus on sustaining your intensity even if it means performing fewer reps and sets.

HIIT can be performed with just your bodyweight or with external weights. Here are exercises you can perform without weight.

Stationary sprint

This exercise is quite simple and requires only a small space. To perform this exercise, simply run at maximum speed on the spot for a minute, then break your pace to a low-intensity jog.


A staple exercise among boxers, shadow boxing is an excellent high-intensity interval training. To perform this exercise, take a boxing stance. Place your foot apart with one-foot forward (lead foot), punch with the arm of your lead foot and follow with the second arm. Perform this exercise at maximum speed for 30 seconds, then alternate with a low-intensity exercise or take a short break to recover.

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