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Knowledge Co-Creation - Profiles of researchers

Seeking to Identify the Effects of Exercise on Executive Function

Keita Kamijo
Assistant Professor, Faculty of Sports Sciences, Waseda University

Taking an interest in the relationship between exercise and the brain

My research activities are rooted in a desire to confirm any potential benefits of exercise and sports on brain health and cognition in addition to physical health. As a child, I played baseball all the way through to my university days. When I was at junior high school we were told that drinking water during practice was not allowed, but by the time I became a senior high school student this advice was turned completely on its head and we were told that we could drink water after all!
My own personal experiences during my formative years of how old-school non-scientific thinking was gradually replaced with a philosophy of scientific training were what made me first take an interest in this field. After I entered graduate school, my interest in competitive sport was replaced by an interest in exercise and sports as a way of supporting people’s general health. I came to believe in the importance of exercise and sports for society at large, and this belief led me to carry out research into the relationship between exercise and brain health.

I majored in psychology as an undergraduate, but for my post-graduate course I decided to study at the University of Tsukuba (Graduate School of Health and Physical Education), which was the leading institution in the study of physical education and sports in Japan at that time. (The School of Sport Sciences had yet to be established at Waseda University.) Instead of focusing on psychology, our laboratory carried out research into exercise physiology, such as motor control. At the time, there were almost no researchers in the world tackling the relationship between exercise and cognitive brain function, and this was what I wanted to study. I read a number of papers in international journals I could find that I thought might be useful to my research, and learned techniques for measuring brain function (brain waves) from my senior colleagues while coming up with my own ways of carrying out experiments and analysis. Specifically, I examined whether the effects of acute exercise on brain function differed depending on the exercise intensity, and I wrote my doctoral dissertation based on this research.

At a Japanese conference with Professor Hillman (2012)

Later, I contacted a young researcher, Dr. Charles Hillman, at the University of Illinois at Urbana-Champaign (he was Assistant Professor at the time) because I wanted to carry out research at the world’s leading institution in the field, the University of Illinois at Urbana-Champaign. The field was a small one. When I contacted him he already knew of the papers I had written in English during my time as a Ph.D. student. (It helped to break the ice when he came straight out and said “So you’re the guy who wrote that paper”!) I stayed at the University of Illinois at Urbana-Champaign for three years from 2009. Professor Hillman and I are close in age, and I was extremely lucky because he acted more like a friend than a boss to me, helping me really enjoy my research in the United States.

Colleagues from Professor Hillman’s laboratory. Assistant Professor Kamijo is in the back row on the far right, and Professor Hillman is in the back row on the far left (2011).

In addition to Professor Hillman, the University of Illinois at Urbana-Champaign has another leading expert in the field in Professor Arthur Kramer. Whereas Professor Hillman’s research has focused on children, the main subject of Professor Kramer’s research has been the elderly. Professor Kramer published a paper in Nature in 1999 showing that a 6-month walking training improved cognitive functions (particularly executive functions) in older adults. This paper led to a rapid increase in interest in this field of research. What’s more, recent research by Professor Kramer’s group showed that walking training actually increased the size of the hippocampus (which controls memory functions) in the elderly participants. The brain shrinks with increasing age, so it is very surprising to see that exercise is capable not only of preventing shrinkage of the hippocampus but actually increasing its size. In this way, the importance of regular physical activity is attracting considerable attention as a way of preventing dementia. It is Professor Hillman who has applied these research methods to childhood research.

Large-scale intervention studies at the University of Illinois at Urbana-Champaign

At the University of Illinois at Urbana-Champaign I took part in a research project investigating children, which is Professor Hillman’s specialist field. Specifically, the research project investigated the relationship between children’s physical fitness and cognitive functions (particularly executive functions). In the project, an afterschool physical activity program was held for elementary school children five days per week for a period of nine months and changes in their physical fitness and cognitive functions were observed. Children’s brains develop naturally during a nine-month period, so even if it was shown that their cognitive functions had improved nine months later it would be impossible to judge whether the effect was the result of the physical activity program or simply down to their natural development. For this reason, a group that did not participate in the physical activity program was established separately from the group that did participate and the changes in both groups were compared. If the groups were allocated on the basis of whether or not the children wanted to participate it may have created bias, such as a tendency to like or dislike physical exercise, and for this reason it was important that the groups were allocated on a random basis.

Diagram: An example of a flanker task. The task asks participants to press a button based on the direction of a centrally presented target fish. In this example, the correct answers from front to back are as follows: left, right, right, left.

This type of research method is called a randomized controlled trial, and because it requires such a large amount of time and effort the data obtained from randomized controlled trials is extremely valuable. During the research project, a total of more than 200 children were studied over a period of five years. A cognitive task was used (called a flanker task), similar to that shown in the diagram, to assess the children’s cognitive functions. During the task, the children were asked to press buttons with their left or right hands based on the direction of a centrally presented target fish and to ignore the flanking fish. When the target fish and the flanking fish are facing the same direction it is less likely that a mistake will be made. However, when the target fish is facing the opposite direction to the flanking fish there is an increased likelihood of making a mistake. In other words, the flanking fish are only there to interfere with the target fish, and the task aims to measure the ability to stay focused on task relevant and ignore task irrelevant information (this ability is referred to as “inhibitory control”). Inhibitory control is one of the executive functions that I will describe later, and it is known to have a close association with academic ability. This is an extremely important cognitive function for children. Such cognitive tasks were carried out before and after the physical activity program and changes were observed in brain activity, response accuracy, and the like.

This research project continued after I returned to Japan and was finally completed last year. A paper describing the research results was published just a few months ago in Pediatrics. The results indicated that the physical activity program improved aerobic fitness and cognitive functions (particularly executive functions). In other words, regular physical activity has the potential to play an important role in the healthy development of children’s brains. The research results were picked up by the New York Times and seem to have caused a big reaction. This is something I am very pleased about on a personal level.

Assistant Professor Kamijo have written chapters in books edited by Professor Hillman and Professor Kramer.
Left: Functional Neuroimaging in Exercise and Sport Sciences (2012: co-authorship with Hillman et al. of a chapter on The Relation of ERP Indices of Exercise to Brain Health and Cognition)/
Right: Enhancing Cognitive Functioning and Brain Plasticity (2009; sole authorship of a chapter on Effects of Acute Exercise on Event-Related Brain Potentials)

     
Exercise can affect people’s success in life!

Freshman students at the School of Sport Sciences during outdoor training (2014).

In the English language the higher-order cognitive function, which is largely mediated by the prefrontal cortex, are referred to as the “executive function.” This has been translated into Japanese as jikkou kinou or suikou kinou but I believe these translations fail to communicate the full meaning of “executive functions.” For example, in English “executive function” also includes the meaning of “executive” in the sense of a leader or manager, such as an executive producer. As a leading expert in research into executive functions in children, Professor Adele Diamond of the University of British Colombia commented in a review article published in Science in 2011 that executive functions are critical for success throughout life in terms of academic success, career and marriage. She cited my paper in her article, and I have high expectations that research into the importance of physical activity for the development of executive functions will attract increasing attention in the future.

Associate Professor Kamijo’s chapter was included in Sports Science and an Active Life, an English language book outlining the research results of the MEXT Global COE program “Sport Sciences for the Promotion of Active Life” (2009-2013), which was edited by Professor Kazuyuki Kanosue of the Graduate School of Sport Sciences, Waseda University.

Our team has persisted with this research in the hope that if we can show people that exercise is “related to academic success,” “improves the brain health,” and “improves the efficiency of study and work” then people who do not really enjoy exercise might be encouraged to give it a try. At the same time, I understand that this challenge will not be easy. I want to utilize the strengths of sports science, which attracts researchers from a variety of different fields, and work alongside other sports science researchers in trying to come up with solutions to the challenge of how we can increase the number of people taking exercise and remove the obstacles to exercise.

Keita Kamijo
Assistant Professor, Faculty of Sports Sciences, Waseda University

In 2006, Assistant Professor Kamijo completed his Doctoral Program in Physical Education, Health and Sport Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba. His specialist fields are health and exercise psychology. After first working as a Research Fellow of the Japan Society for the Promotion of Science (DC2), a Research Fellow at the Graduate School of Comprehensive Human Sciences, University of Tsukuba, a Postdoctoral Research Scientist at the National Institute of Advanced Industrial Science and Technology, and a Research Associate at the Faculty of Sport Sciences, Waseda University, he spent three years from 2009 working as a Postdoctoral Associate at the University of Illinois at Urbana-Champaign (the two years from 2009 to 2010 were spent on the Japan Society for the Promotion of Science Postdoctoral Fellowships for Research Abroad). He was appointed to his current post in 2012. Awards include the Japan Society of Physical Education, Health and Sport Science Award (2006); the Encouraging Prize at the Japan Society of Exercise and Sports Physiology (2008); The 27th Meiji Yasuda Life Foundation of Health and Welfare Research Grant Outstanding Research Award (2012); and the Waseda Research Award (High-Impact Publication)(2014). Among other books, he has co-authored Sports Seishin Seirigaku [Sport Psychophysiology] (Nishimura Syoten, 2012).