A recent article in the New York Times, written by Gretchen Reynolds, looked specifically at this last gain of intellectual growth. The article references a study written by Nokia et. al. that compared different groups of rats performing aerobic exercise, high intensity interval training, and anaerobic resistance training, looking at their change in adult hippocampus neurogenesis post 6-8 weeks of exercise. The authors states that hippocampal neurons are responsible for many actions including the ability to learn. It is important to note that that authors reference a correlation between adult hippocampal neurogenesis and the protein brain-derived neurotrophic factor.
To compare exercise groups’ neurogenesis, the authors of the study, stained the rats’ hippocampus marking the change in the number of doublecortin-positive cells. The study’s results showed that the number of doublecortin-positive cells in the hippocampus had a strong correlation with the distance rats performing aerobic exercise would run on their running wheels. The results did not show a significant correlation with the number of doublecotin-positive cells generated and the speed at which the rats ran. Lastly, the results did not show a correlation between the number of doublecortin-positive cells produced and the change in strength that the rats gained from anaerobic resistance exercise.
The study by Nokia et al concluded that only sustained aerobic exercise, such as running, had a significant positive effect on adult hippocampal neurogenesis. Interval exercise was found to cause minimal neurogenesis, and anaerobic exercise was found to cause no neurogenesis.
Gretchen Reynolds, in her New York Times article, cited Dr. Nokia, stating that the studies’ results suggest that sustained aerobic exercise, such as running, is the best type of exercise for brain health of humans. Reynolds, also referenced the role of the protein “brain-derived neurotrophic factor”, as hypothesized by the study’s authors, being an inducer of neurogenesis. Reynolds writes that Dr. Nokia referenced past studies showing brain-derived neurotrophic factor is not produced during anaerobic resistance training, and therefore may cause the neutral effect on hippocampal neurogenesis. Dr. Nokia is also noted to have hypothesized that the reason high intensity interval training has a minimal effect on neurogenesis is due to the high levels of stress it causes in the body, and stress is known to decreased hippocampal neurogenesis.
Reynolds ends her article with Dr. Nokia’s disclaimer that hippocampal neurogenesis is not the only change that can be effected in the brain by exercise. Dr. Nokia suggests in Reynold’s article that interval exercise and anaerobic exercise could cause many other positive effects in the brain, so those who enjoy weight training or interval exercise should not stop.
As a runner, I tend to want to take liberty with the results of the Nokia et al study and Reynold’s article, reassuring myself that running will make it easier for me to learn new things. As I am trying to learn a new language right now, I certainly hope this is somewhat true. Either way, I will continue to run for the physical and emotional benefits, and I will definitely tease my husband and family that my running is making me smarter, so they better watch out!