HIIT - Benefits and Contraindications of High Intensity

HIIT, or high-intensity interval training, is a method that has gained popularity in recent years.

Studies have confirmed that it has extensive health benefits. However, it may be contraindicated for a small number of people.

This article details what HIIT consists of, its benefits, and contraindications backed by scientific evidence.

What is HIIT?

The abbreviation HIIT stands for “ High-Intensity Interval Training ” in English, which translates as high-intensity interval training. HIIT is a method that allows the improvement of muscular strength and endurance.

In a HIIT routine, maximum intensity exercises are alternated with low-intensity exercises. The contraindications and benefits of HIIT are described below to say yes or no to this training method.

A HIIT training routine consists of alternating between 20 seconds of high-intensity exercises with 20 seconds of cardio exercises and resting the next 10.

The idea is to combine exercises that increase the heart rate (for example, running at maximum speed) with strength exercises in functional circuit mode. The cycle is repeated about four times (1).

HIIT benefits

HIIT workouts are ideal for those who are carrying out weight loss processes. Its benefits are reducing the body mass index, accelerating the metabolic rate, and reducing body fat percentage. It is a method proposed by trainers for overweight people. The benefits of HIIT are:

  1. Increase respiratory capacity

Studies confirm an increase in aerobic endurance and maximum respiratory capacity ( VO2 max ) when doing HIIT (2) (4). Some authors affirm that with only two months of adaptation, significant changes are generated in the capacity to transport and absorb the amount of oxygen in the blood.

  1. It can accelerate the basal metabolic rate.

This is one of the most controversial HIIT benefits. Some authors claim that HIIT accelerates the basal metabolic rate. (5) However, there are still studies to be done to confirm this. One of the benefits of HIIT is to normalize glucose metabolism, which is ideal for preventing chronic diseases such as type 2 diabetes.

  1. Increase testosterone levels

High-intensity interval training increases testosterone. This is explained by passion. By working hard, the body releases more sex hormones to counteract the effects of muscle stress.

  1. Eliminate body fat

The main benefit of HIIT is the ease with which a person can shed body fat. This training method was specially designed for those who have overweight and obesity problems. (4)

  1. Short duration and easy adaptation

The last benefit of HIIT is its short duration. Suppose you are one of those who always run to get to the office and go to the gym. Or try studying and exercising simultaneously; the high intensity interval system is ideal for you. In 30 minutes, you will be ready, not to mention that it is one of the methods with the best adaptation potential and does not require extensive equipment. (4)

HIIT contraindications

High-intensity interval training isn’t for everyone. If you haven’t been in sports in a while, it’s not good to start with a return to exercise with HIIT. The contraindications of HIIT are detailed below:

  1. People with joint and tendon problems or injuries

If you have experienced a knee or shoulder injury, you should look for other high-intensity exercise options that do not involve collective impact. High-intensity loads can be dangerous in re-injuring the joints and tendons. On the other hand, supplements such as hydrolyzed collagen, glucosamine, and chondroitin effectively prevent wear and tear.

  1. People with respiratory problems or asthma

You need to have a good aerobic base to start high intensity interval training. People with asthma or respiratory problems should not dabble in HIIT if they have not tried another type of physical discipline.

  1. Take blood pressure medications.

One of the contraindications of HIIT is that this type of training is not recommended for people other than those who take medication for blood pressure. Working at high intensity can cause severe cardiac events.

  1. Pregnant women

Pregnant women should not do HIIT. Jerky movements, jumping, and a fast heartbeat can cause problems for the fetus. Although this training method effectively loses extra pounds after pregnancy, other types of lower intensity exercise routines such as Pilates are recommended during management.

  1. People with uncontrolled diabetes

One of the contraindications of HIIT is for those with uncontrolled diabetes. Particular caution should be taken in doing activities of this type. The expenditure of calories is usually high and hypoglycemic events can occur.

  1. Knee or shoulder injuries

If you have experienced a knee or shoulder injury, you should look for other high-intensity exercise options that do not involve collective impact. High-intensity loads can be dangerous in re-creating joint and tendon disorders.

Does HIIT work for weight loss?

When working at low intensity, the slow muscle fibers are the ones that work; This type of fiber uses fat deposits as a source of energy. When working with high-intensity loads, fast muscle fibers are being worked on, the various threads that use muscle glycogen for power.

In HIIT training, both intensities are alternated, which allows the development of both types of muscle fibers. This fact and the improvement of the cardiovascular system are the main benefits of HIIT.

This training system has been used with excellent results to reduce obesity in children and people with high levels of a sedentary lifestyle. (4)

Metabolism and HIIT

In his workouts, the difference between intensities and loads allows the body to use fatty acids as an energy source better. For this reason, some authors maintain that HIIT is capable of accelerating metabolism.

The use of slow muscle fibers does not occur in a traditional gym routine, leading to the need to supplement it with aerobic exercises. HIIT workouts focus on the number of repetitions and allow you to work on myofibrillar muscle hypertrophy.

Tips when starting HIIT

When interval training is high intensity, precautions should be taken to finish the sessions without problems. Here are five tips to follow when starting HIIT:

  1. Do not combine it with thermogenic

Thermogenic, like caffeine, is not recommended for a HIIT workout. These substances increase blood pressure and heart rate, which can cause damage to health.

  1. Drink homemade isotonic drinks

When doing HIIT, the water loss due to sweating is usually excessive. Sports drinks can help a person not become dehydrated after a training session.

  1. Do not go to the sauna after training.

Going to the sauna after training can cause a drop in blood pressure and even fainting. High temperatures can have negative repercussions on the cardiovascular system. We recommend the contrast shower or myofascial release if you opt for a muscle recovery method.

  1. Do not combine it with the ketogenic diet.

Do not combine it with high-intensity interval training if you are on the keto diet or other low-carb diets. Performing this type of training with deficient glucose levels can lead to loss of consciousness.

  1. Drink more water during the day

When doing HIIT, you are likely to sweat in bulk. It is essential to know that the amount of water that should be taken during the day increases by at least 500 mL when doing HIIT. If the expense of water is not compensated through sweat, mild symptoms such as dry skin and severe symptoms may appear, such as kidney disorders.


  • High-intensity interval training or HIIT consists of alternating maximum-intensity exercises with low intensity or aerobic exercises. The rest between sets is minimal.
  • This training method is one of the best workouts for shedding body fat.
  • Doing HIIT burns a lot of calories. However, experts have not yet proven the theory that it can accelerate metabolism.
  • High intensity interval training is dangerous for beginners or people who are not used to exercising regularly.
  • Contraindications to HIIT are people taking medications for pressure, knee injuries, and pregnant women.
  • HIIT routines resemble other methods such as circular trainingcalisthenics, and Tabata.


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