``Research on the effects of exercise on cognitive function contains many biases''

Many people believe in the theory that ``

exercising has a positive effect on cognitive ability, '' but a research team led by Daniel Sanabria Lucena at the University of Granada found 109 cases of ``exercise has a positive effect on cognitive ability. An analysis of the research concluded that there is 'no conclusive evidence that exercise improves cognitive performance.' Lucena has responded to an interview with overseas media EL PAÍS , talking about the limitations of research that shows that sports and other exercises have a positive effect on brain function.

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``The research by Lucena et al. is considered to provide uncertainty about human health. How can people learn about this uncertainty?'' It is important to focus on science education from the beginning,” he said. According to Lucena, in order to understand the mechanism of science, it is important to understand that researchers have biases and prejudices.

Lucena added, ``People tend to seek clear and simple health advice, including mental health. It's important to be aware,' he said.

Lucena recalled that when he taught two contradictory theories to a student, he was asked, 'What should I believe?' It is a field of study in which hypotheses arise after accumulating evidence.”

Of the genesis of the research that has led to the belief that exercise has a positive effect on cognition, Lucena said, ``Over the past two decades, as a result of increased interest in the subject, there has been a growing interest in not only the physical well-being of exercise. Analyzes of the cognitive benefits of exercise have advanced: Many studies of large participants, up to thousands of participants, have examined levels of physical activity and the relationship between cardiovascular fitness and cognitive function. We have attempted to establish associations, and although these studies have found correlations, it should be noted that 'correlation' is not the same as 'causation.' I'm here.

To prove causality, a technique called an '

intervention study ' is commonly used, in which participants are randomly assigned to an experimental group that exercises or a control group that does not exercise. However, an analysis of 109 studies on exercise and cognitive function found that only longitudinal investigations and no intervention studies were conducted to study the effects of regular exercise on cognitive and brain function. did not. That's why it's hard to conclude that exercise helps cognitive function in these studies, argues Lucena.

In addition, there is concern that these studies may have a '

publication bias ' in which negative or invalid results are not published, selectively reporting only a subset of results when desired results were not obtained. It has been suggested that doing so may distort our understanding of the true effects of exercise on cognitive function.

As an example of publication bias, Mr. Lucena cites research on ' the cognitive benefits of bilingualism ' and 'the effect of mental fatigue on physical performance.'

According to Lucena, from 2000 to 2010 there was a surge in research results that ``people who can speak multiple languages have higher cognitive abilities than those who speak only one language,'' resulting in bilingual schools, etc. A number of language schools were established in However, a prominent body that has been conducting research in the field of bilingualism has shown that the cognitive benefits of being bilingual are publication biases in which positive results are published more often than negative ones.

In addition, Lucena et al. conducted a re-experiment on the widely believed research in sports science that ``doing mentally demanding work just before exercising lowers performance than if you do not work.'' No performance degradation was observed. Furthermore, when Lucena et al. analyzed these studies, it turned out that these studies were conducted with a small number of participants. Running an experiment without enough participants can lead to publication bias and poor quality research results.

Similarly, as a result of investigating a study that 'a weak electric current is passed through the brain to improve exercise performance', Mr. Lucena reported that such results were not obtained.

On the other hand, Mr. Lucena said, 'Our analysis results do not mean that the effects obtained from these research results do not exist.' He said the reason for this is that ``the lack of evidence does not prove that there is no effect,'' and ``if more high-quality studies were done, the exact effect could be obtained.'' says.

Next, in response to the question, ``Does the intentional selection of participants in the research greatly affect the results?'' Lucena affirmed, ``It is possible to have a big impact.''

As an example, Mr. Lucena said, ``I want to investigate the effects of exercise on cognitive function and brain performance in order to prevent cognitive function decline, so I am looking for elderly people.'' He points out that the focus will be on elderly people who are interested in the effects on the brain.

It is said that it is impossible to examine the `` placebo effect '' that is standard in the medical world when conducting experiments with this method of recruiting participants. In addition, it has been pointed out that accurate results may not be obtained when the exercise training group is divided into a group that does not undergo exercise training and the original cognitive ability of the participants in the exercise training group is low. increase.

There are concerns that such inter-participant issues may lead to publication bias. It has also been pointed out that while many studies with positive results showing the effects of exercise on cognition may be published, studies showing negative results risk being ignored or excluded. increase. Therefore, biases such as publication bias and optimal study design should be considered when conducting research on exercise and cognitive performance.

Furthermore, in response to the opinion that ``explanation of results in psychological research may focus too much on the effects of the brain,'' Lucena said, ``One of the risks when studying the effects of exercise and mindfulness is that individual contextual factors are often overlooked.' “Factors such as parental social and economic status and parental support have been shown to be stronger predictors of academic and career success than individual cognitive ability. Background is often neglected and the focus is more on individual characteristics and abilities,” Lucena exemplifies.

Such a narrow interpretation can lead to messages that overly impose personal responsibility. According to Lucena, weight gain tends to ignore the influence of external factors such as the person's economic and environmental factors. In addition, it has been pointed out that if a person becomes ill due to lack of exercise, the person's social factors may be neglected and only weakness of will will be pursued.

“Such messages are said to ignore the complex interplay between the social and environmental factors that shape individual choices and lives,” Lucena said. It's important to recognize that an individual's results are shaped by many factors, not just the person's responsibility.'

Mr. Lucena recommends exercising from a health standpoint, but cautions against forcing children to take lessons such as sports for their mental and physical development. According to Lucena, it is important to let children participate in the sport if they think they like it, and not to force it to seek some beneficial effect on the child's psyche. Lucena also points out that individuals should not be held responsible for all physical and mental health.

in Science, Posted by log1r_ut