Moderate-intensity exercise has important brain-boosting effect

Working out can improve cognitive abilities such as problem-solving in young adults, and some forms of exercise offer greater benefits than others, according to new Tsinghua research.

A study of two popular types of workout has suggested that for young adults, a smarter regime is better than a harder one when it comes to boosting executive function through exercise.

Regular moderate exercise — such as brisk walking, cycling, swimming, and jogging — appears to boost executive function in young adults more than high-intensity interval training.

The research led by Xindong Ma, a professor at Tsinghua University’s Division of Sports Science and Physical Education, compared two groups following a 12-week physical activity programme, as well as a control group that didn’t participate in exercise training.

Ma’s team found that those doing regular moderate-intensity continuous training (MICT) performed better in executive function tests than those doing high-intensity interval training (HIIT) when compared to the control group. This was corroborated by measurements of blood flow in the brain.¹

MICT is consistent, moderate aerobic exercise sustained over time, such as brisk walking, cycling, swimming, and jogging. It boosts cardiovascular fitness without excessive strain. HIIT involves alternating between intense exercises and periods of rest or lower intensity. Examples include sprints, jump squats and burpees.

HIIT has the advantage of achieving similar physiological adaptations as MICT, but within a shorter time frame. However, prolonged HIIT was reported to lead to fatigue and decrease cerebral oxygenation in the brain compared to MICT, which may explain the results, speculates Ma. “Maintaining a relatively constant cerebral blood flow is fundamental to preserving normal brain function,” he says.

Conversely, in previous studies on sedentary elderly individuals, HIIT has been shown to enhance memory performance to a greater extent than MICT. Several studies have also indicated that HIIT leads to greater improvements in cardio-respiratory fitness and overall vascular function compared to MICT.

Those studies have tended to focus on children, adolescents and the elderly, while studies on young adults are rarer, says Ma, which is what makes this finding more interesting. 

The Tsinghua team used transcranial Doppler flow analysis to assess speed and direction of blood flow in the brains of study participants. 

Results 

The study design comprised 93 healthy adults aged between 20 and 30, who were randomly assigned to a HIIT, MICT, or control group. Each exercise group performed 40 minutes of HIIT or MICT three times a week, while the control group received only health information.

The researchers then sought to measure executive function – which involves skills like problem-solving, planning, and organizing. To do this, they applied the Trail Making Test (TMT), a widely used cognitive task that assesses skills such as problem-solving and attention by asking participants to order and connect disordered numbers and letters.

Both exercise groups showed significant improvements in TMT completion time compared to the control group, but the MICT group showed better results than the HIIT group.

Then, to better understand the mechanisms, the researchers employed transcranial Doppler flow analysis, a non-invasive method that uses ultrasound technology to assess the speed and direction of blood flow in the brain in real time. The results showed that the MICT group had more significant improvements in cerebral blood flow than the HIIT group.

Given the subtle differences seen between MICT and HIIT in this study group, future research would do well to explore longer intervention periods and different exercises to gain a fuller picture and understanding of the mechanism, says Ma.

The more we know, the better we can be at preventing cognitive decline across a lifetime, he explains. 

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Editors: Guo Lili, Liu Shutian

Designer: Wang Zekun

Reviewers: Lin Yuan, Chen Ken

Reference

1.     Liu, J., Min, L., Liu, R., Zhang, X., Wu, M. et al. The effect of exercise on cerebral blood flow and executive function among young adults: a double-blinded randomized controlled trial Scientific Reortsp 13, 8269 (2023) doi: 10.1038/s41598-023-33063-9