A 10-week study conducted in Germany compared the learning performance and immune system activity of individuals engaged in cardiovascular exercises (cycling) to a control group (stretching exercises). The results showed no significant difference in learning performance between the two groups. However, those in the cardiovascular group who exhibited greater learning also demonstrated a more robust immune response following their exercise sessions.
The study, which was published in Biological Psychology, suggests that the immune system might play a central role in facilitating the positive effects of exercise on brain function.
Cognitive and learning abilities tend to decline with age. As the average life expectancy increases in the modern society, there are more and more people who are seriously affected by this age-related cognitive decline. This has prompted scientists to look for ways in which cognitive functioning can be improved and age-related cognitive decline slowed.
Studies have indicated that physical exercise might be of help. It is a lifestyle factor that is often relatively easy to modify and research indicates that physical activity at a younger age is associated with lower risk of developing dementia and cognitive impairments later in life. Additionally, studies on rodents found that physical activity improves learning and memory (of rodents). This was accompanied by enhanced neuroplasticity in brain areas related to memory. Neuroplasticity is the brain’s ability to reorganize and adapt by forming new neural connections, allowing for learning, memory, and recovery from injuries.
Laura A. Kuhne of the University of Hamburg, the study’s lead author, and her colleagues sought to determine if repeated cardiovascular exercise post-learning could enhance learning and memory compared to non-cardiovascular exercise. Cardiovascular exercises, commonly known as cardio or aerobic exercises, elevate heart rate and breathing. Many experts advocate for these exercises due to their cardiovascular system benefits. To test this, the researchers set up an experiment.
The study comprised 52 residents from Hamburg, Germany, who were recruited via flyers. The participants’ average age was 27, ranging from 20 to 40 years, with 40 being female. Each participant received 100 EUR for attending all training sessions, and an additional 8 EUR/hour or course credits (for students) during assessments. In total, participants earned between 152 and 212 EUR for their involvement.
The participants were randomly split into two groups. Over ten consecutive weeks, both groups attended two individual training sessions weekly. The first session was exercise-only. In the subsequent 18 sessions, participants began with a 21-minute vocabulary learning task, followed by 45-55 minutes of physical exercise.
The vocabulary task involved learning associations between specific images and pseudowords (fabricated words). As the sessions progressed, participants were expected to increasingly identify the correct image-pseudoword pairs and spot incorrect pairings. Post-learning, one group engaged in cardiovascular exercises, cycling on an ergometer, while the other group performed stretching exercises. Unsurprisingly, the cycling exercises resulted in significantly higher heart rates than stretching.
Following the final learning session and a month-long follow-up, participants were assessed on their pseudoword retention. Blood samples were taken from the participants at the beginning and end of each session.
The results indicated that the cardiovascular training group (cycling) improved their cardiovascular fitness compared to the non-cardiovascular group (stretching). However, the average learning outcomes were comparable between the two groups.
Blood sample analyses revealed elevated Interleukin-6 levels in the cycling group post-exercise, absent in the stretching group. Interleukin-6 is a molecule produced by the immune system in response to infection and injury.
Levels of Interleukin-1 receptor antagonist and Interleukin-4, two other immune molecules, diminished in the stretching group but remained unchanged in the cycling group. Further evaluations showed that cyclists who learned more during a session also experienced higher increases in Interleukin-6 and Interleukin-1 receptor antagonist levels.
“These results suggest that the immune system may act as a mediator of exercise-induced cognitive benefits,” the study authors concluded.
The study makes a valuable contribution to the scientific understanding of the links between immune responses, learning and exercise. However, it should be noted that the study sample was small, consisted mainly of young people, and most of the participants were female. Results on bigger samples and other demographic groups might not yield equal results.
The study, “Cardiovascular exercise, learning, memory, and cytokines: Results of a ten-week randomized controlled training study in young adults”, was authored by Laura A. Kuhne, Anna-Maria Ksiezarczyk, Klaus-Michael Braumann, Rüdiger Reer, Thomas Jacobs, Brigitte Roder, and Kirsten Hotting.