High-intensity interval training is under scrutiny by science and society

Ruben Fernandez-Rodriguez/The Conversation
Although he train High-intensity intervalsHigh-intensity interval trainingits English acronym) is not new—it was first described in the 1950s—but it has received particular attention from the scientific community and society in the past decade.

This approach was originally developed to improve the physical performance of athletes. exercise It is used in conjunction with traditional continuous strength methods for both healthy people and those with medical conditions. Research shows it has a wide range of benefits Physical and mental health.

HIIT is defined as train It intersperses high intensity (85-90% of maximum aerobic capacity) with softer parts (active rest), all of which are repeated for a certain number of blocks.

Its basic “ingredients” can vary: the type of exercise (running, cycling, functional or strength training, etc.); the frequency (1 to 5 days per week); the duration of the session (6-75 minutes); the duration of high-intensity work (90-140 seconds); the duration of active rest (120-140 seconds); the number of blocks that make up the session (7-14), or the time between them.

Such a wide range of possibilities means that the protocols applied are very diverse. So what do we talk about when we talk about HIIT? This is the question we tried to answer with our research, collecting 103 original articles with a total of 4,037 participants, from children and teenagers to adults.

For the purpose of analyzing the works, we divided these forms of physical activity into three main categories:

Mix HIIT (running or cycling) with normal. It shows the longest working time (about 143 seconds) and active rest time (about 138 seconds).

Long HIIT (running only). It has the longest session time (about 40 minutes).

Short HIIT (bike only). It features the shortest session time (24 minutes), the highest number of blocks, the shortest work time (90 seconds), and active breaks (121 seconds).

Next we asked ourselves the following question: Which type of HIIT is most effective for improving cardiorespiratory fitness?

The good news is that all three significantly improve maximum aerobic capacity, the top rate at which a person can capture, use and transport the oxygen they breathe. It is a key measure of a person’s fitness, cardiovascular health and physiological health.

However, there is a nuance: we observed that the effect of long-term HIIT was slightly greater, especially in people aged 20 to 44 years.

Additionally, based on our research, we created a tool (AGReHIIT) so that researchers and exercise and health professionals who want to create their own HIIT “recipes” can have easy-to-follow guidelines.

When choosing a modality, our results translate into the following advice: we must choose the modality that we like best and that encourages us to exercise without fear of variation and to remain flexible. You just have to remember that in certain stages of certain diseases, it may be easier and safer to apply the regimen on a bike; for example, people with cardiovascular disease or obesity.

We know that no matter which option we choose, HIIT activates different health mechanisms. For example, when tissues are deprived of oxygen, the release of substances such as lactate increases, and a protein called brain-derived neurotrophic factor (BDNF) also increases, which is generally beneficial to brain metabolism and health.

In patients Frustration HIIT has been shown to reduce chronic, low-grade inflammation present in many chronic diseases. It can also improve cognitive function, performance, and the ability to concentrate.

In addition, our bodies are able to more efficiently capture and absorb available oxygen to “feed” our muscles and brain, and as we noted, optimize our cardiorespiratory fitness. This can improve cerebrovascular function and reduce the risk of illness and death.

In short, any type of HIIT is beneficial, whether we have a disease or not. If you are an athlete or preparing for a test, change your approach based on your goals. If you are a clinician, trainer, or rehabilitator, adjust based on the patient or client’s preferences and clinical conditions, and choose products that provide greater safety, compliance, and enjoyment.