December 30, 2019

7 benefits of high-intensity interval training (HIIT)

7 Vorzüge von hochintensivem Intervalltraining (HIIT)

Even though most people know that physical activity is healthy, experts estimate that around 30% of people worldwide don't get enough of it (1).

Unless you have a physically demanding job, a dedicated fitness program is probably your best option for getting active. Unfortunately, most people feel that they don't have enough time to exercise (2, 3).

If you recognize yourself, then maybe it's time to try high-intensity interval training (HIIT). HIIT is a collective term for training sessions that include short periods of intense exercise alternating with recovery periods.

One of the biggest benefits of HIIT is that you can reap maximum benefits in a minimum amount of time. This article will explain what HIIT is and what the main health benefits of this type of training are.

What is high-intensity interval training (HIIT)?

HIIT involves short bursts of intense exercise alternating with less intense recovery periods. Interestingly, HIIT may be the most time-efficient way to exercise (4, 5).

Typically, a HIIT training session lasts between 10 and 30 minutes. Despite the short duration of the training sessions, HIIT has health benefits equivalent to training sessions twice as long at moderate intensity (6, 7).

The actual activity performed during HIIT varies and can include sprinting, cycling, jumping rope or other bodyweight exercises.

For example, a HIIT training session on a cycle ergometer could consist of 30 seconds of cycling at maximum speed and high resistance followed by several minutes of slow cycling at low resistance. This would be a "round" or a "repetition" and typically 4 to 6 of these rounds are completed per training session.

The specific duration of the intense efforts and recovery periods afterwards will vary based on the activity and intensity chosen. However, no matter how exactly a HIIT workout is put into practice, the high-intensity intervals should include short bursts of maximum effort to get your heart rate up (8).

HIIT not only delivers the benefits of longer conventional workouts in a much shorter period of time, but may also have some unique health benefits (4).

1. HIIT can burn a large amount of calories in a short period of time

You can burn a lot of calories quickly using HIIT workouts (9, 10).

One study compared the amount of calories burned during 30 minutes of HIIT training, 30 minutes of training with weights and 30 minutes of running or cycling. The researchers found that HIIT burned 25 to 30% more calories than the other forms of exercise (9).

In this study, one HIIT repetition consisted of 20 seconds of maximum effort followed by 40 seconds of rest. This means that the subjects in the HIIT group were actually only exercising for 1/3 of the time that the subjects in the runner and cyclist groups were exercising.

Even though each training session in this study was 30 minutes long, HIIT training sessions are often much shorter than traditional training sessions. This is because HIIT allows you to burn the same amount of calories in a shorter period of time.

Summary: HIIT could help you burn more calories than traditional training or the same amount of calories in a shorter period of time.

2. your metabolic rate is elevated for hours after a HIIT training session

One of the ways HIIT helps you burn calories comes into play after you've already finished your workout. Several studies have shown HIIT's impressive ability to increase your metabolic rate for several hours after your workout (11, 12, 13).

Some studies have even found that HIIT increases post-workout metabolic rate more than jogging or training with weights (11). The same study also observed that HIIT shifts the metabolism more towards using fat instead of carbohydrates as an energy source.

Another study showed that just two minutes of HIIT in the form of sprints increased metabolic rate over 24 hours as much as 30 minutes of running (14).

Summary: Due to the intensity of the training sessions, HIIT can increase the metabolic rate for hours after training. This results in additional calories burned long after you have finished your training session.

3. HIIT can help you lose fat

Studies have shown that HIIT can help you lose fat.

One study review looked at 13 clinical trials with a total of 424 overweight and obese subjects. Interestingly, this review concluded that both HIIT and traditional moderate-intensity cardio training can reduce body fat and waist circumference (15).

Additionally, one study found that people who performed a 20-minute HIIT training session three times a week lost 2 kilos of weight within 12 weeks - without any changes to their diet (16). Perhaps even more important was the fact that a 17% reduction in visceral fat - the unhealthy fat in the abdomen that surrounds the organs - was observed.

Several other studies also suggest that body fat can be reduced with HIIT despite its short duration (17, 18, 19). However, just like other forms of exercise, HIIT may be most effective for fat loss in those who are overweight or obese (20, 21).

Summary: High-intensity intervals can produce similar fat loss to traditional endurance training, even at a shorter duration. In addition, HIIT can reduce unhealthy visceral fat.

4. HIIT could help you build muscle

In addition to helping with fat loss, HIIT may also increase muscle mass in certain individuals (21, 22, 23). However, this muscle building primarily occurs in the muscles that are used the most, which in HIIT are generally the muscles of the core and lower body (16, 21, 23).

Additionally, it is important to note that an increase in muscle mass is more likely in individuals who were less active to begin with (24). Some studies with active subjects have not observed an increase in muscle mass with HIIT training programs (25).

Training with weights remains the 'gold standard' when it comes to increasing muscle mass, but high-intensity intervals may support modest muscle growth (24, 25).

Summary: If you're not very active, you might gain some muscle mass through a HIIT training program, although not as much as through training with weights.

5 HIIT can increase oxygen uptake capacity

Oxygen uptake refers to the ability of your muscles to use oxygen and endurance training is typically used to increase oxygen uptake. Traditionally, this consists of long sessions of continuous activity and activities such as running or cycling.

However, HIIT appears to be able to produce the same benefits within a shorter period of time (20, 21, 27). One study found that five weeks of HIIT training with four 20-minute workouts per week could increase oxygen uptake by 9% (6). This was almost the same improvement that was observed in the other study group, which trained on a cycle ergometer for 40 minutes four days a week at a constant intensity.

Another study found that eight weeks of cycle training on an ergometer using traditional training or HIIT training increased oxygen consumption by about 25% (7). Again, the duration of training was very different between the groups: 120 minutes per week for the group doing traditional endurance training and only 60 minutes per week for the HIIT group.

Numerous other studies have also shown that HIIT can increase oxygen consumption (25, 28).

Summary: High-intensity interval training can increase oxygen consumption to the same extent as traditional endurance training, even at half the training duration.

6 HIIT can lower heart rate and blood pressure

Hit could also have important health benefits. A large body of research suggests that HIIT can lower heart rate and blood pressure in overweight and obese individuals, who often have high blood pressure (20).

One study found that eight weeks of HIIT training on a cycle ergometer lowered blood pressure in adults with high blood pressure as much as traditional endurance training (7). In this study, the endurance training group exercised four days a week for 30 minutes each, while the HIIT group exercised three days a week for 20 minutes each. Some researchers have found that HIIT may lower blood pressure even more than the regularly recommended moderate-intensity endurance training (29).

However, HIIT typically does not appear to change blood pressure in normal-weight people with normal blood pressure (20).

Summary: HIIT can lower blood pressure and heart rate in overweight or obese people with high blood pressure.

7 HIIT can lower blood sugar levels

Blood sugar can be reduced by HIIT programs lasting less than 12 weeks (20, 30). A summary of 50 different studies concluded that HIIT can not only lower blood sugar, but can also reduce insulin resistance to a greater extent than traditional training at a constant intensity (31).

Based on this information, it is possible that HIIT training could be particularly beneficial for type 2 diabetics. In fact, some studies conducted with type 2 diabetics have shown the effectiveness of HIIT in improving blood glucose levels (32).

Research conducted with healthy individuals suggests that HIIT may be able to reduce existing insulin resistance even more than traditional exercise at a constant intensity (27).

Summary: High-intensity interval training may be particularly beneficial for people who need to lower their blood glucose levels or suffer from insulin resistance. These improvements can be seen in both diabetics and healthy people.

How to get started with HIIT training

There are many ways to add high-intensity intervals to your program. To start, you simply need to choose your activity (running, cycling, jumping rope, etc.). Then you can experiment with different lengths of training and recovery periods. Here are some simple examples of HIIT workouts:

Pedal on a cycle ergometer for 30 seconds as fast as you can at high resistance. Then cycle at a slow speed with low resistance for 2 minutes. Repeat this pattern for 15 to 30 minutes.
After some jogging to warm up, sprint as fast as you can for 15 seconds. Then walk or jog at low speed for 2 minutes. Repeat this pattern for 10 to 20 minutes.
Perform jump squats as fast as you can for 30 to 90 seconds. Then rest for 30 to 90 seconds, during which you either simply stand still or walk around. Repeat this pattern for 10 to 20 minutes.

These are just simple examples to get you started. Modify your program based on your own preferences.

Conclusion

High-intensity interval training is a very effective form of exercise and could help you burn more calories than other forms of exercise. Some of the calories burned come from an increase in metabolic rate that lasts for hours after the workout.

All in all, HIIT produces many of the benefits of other forms of exercise in a shorter period of time. These benefits include a reduction in body fat, heart rate and blood pressure. HIIT may also help to lower blood sugar levels and improve insulin sensitivity.

So if you're short on time and want to get active, consider high-intensity interval training.

References:

Source: https://www.healthline.com/nutrition/benefits-of-hiit

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