Brain Gains

Short-duration, light-intensity exercises can significantly increase cerebral blood flow in the prefrontal cortex (PFC) of children, according to new research from Waseda University, Japan. The researchers used functional near-infrared spectroscopy (fNIRS) to monitor changes in oxygenated hemoglobin (oxy-Hb) levels, revealing how different exercises impact brain activity in young people. These findings suggest that even brief, low-intensity physical activities could play a critical role in supporting cognitive development and combating sedentary behavior in children.

The research team, led by doctoral student Takashi Naito, along with Professors Kaori Ishii and Koichiro Oka, aimed to fill a gap in understanding how light-intensity exercises affect cerebral blood flow in the PFC – a region of the brain crucial for executive functions such as decision-making, attention, and memory. While previous studies have established the benefits of moderate-to-vigorous exercise on cognitive function, less was known about the impact of lighter activities, particularly in children.

“Even light-intensity physical activity has health benefits,” says Naito. “We aimed to develop an exercise program that could be easily performed during homeroom or between classes in schools to prevent sedentary behavior in children and positively affect their brains.

To investigate this, the team recruited 41 healthy children, aged 10 to 15 years, and monitored their brain activity during seven different light-intensity exercises. These exercises included upward stretch, shoulder stretch, elbow circles, trunk twist, washing hands, thumb and pinky, and single-leg balance. The children performed each exercise for either 10 or 20 seconds, with fNIRS used to measure oxy-Hb levels in real-time.

Unlike other imaging methods, fNIRS is non-invasive and allows for the monitoring of brain activity in naturalistic settings. By capturing the variations in oxy-Hb, the researchers were able to assess how effectively each exercise stimulated blood flow to the PFC.

“fNIRS has some disadvantages compared to fMRI, such as its capability to measure changes only in the superficial layers of the brain and lower spatial resolution,” says Naito. “However, fNIRS has the advantage of being able to measure while the body is moving (within reason) and in natural postures (e.g., standing or sitting). To achieve the measurement during exercise in this study, fNIRS was the only choice.” 

Results showed that most of the exercises led to significant increases in oxy-Hb levels in the PFC compared to the resting state, indicating enhanced cerebral blood flow. Notably, exercises that involved dynamic movements, such as the single-leg balance and trunk twist, produced the most pronounced increases in oxy-Hb levels. This suggests that even short bursts of light physical activity can effectively engage the PFC, potentially supporting cognitive functions.

However, not all exercises were equally effective. Static stretching exercises with monotonous movements did not result in significant changes in oxy-Hb levels.

“The experiments were performed with two patterns of seven exercises, twice per exercise, for 10 and 20 seconds per movement, and the order was randomized for all children to remove the influence of order effects,” says Naito. “We took great care and made significant effort to accurately integrate the participants' data for each exercise and pattern.”

The researchers emphasized the need for further studies to determine whether these increases in blood flow translate to long-term cognitive improvements. 

“Based on the findings of this study, we are now developing a light-intensity exercise program lasting a few minutes and examining whether it positively affects not only cerebral blood flow but also children's cognitive functions,” says Naito. “We plan to promote our research so that many schools will implement the program, which anyone can easily perform, to prevent sedentary behavior in children and to improve cognitive functions.” 

^{Credit: Collage created using Adobe Stock images}