It is a widely acknowledged fact that exercise is essential to maintain good physical health. But new research from McMaster University has pegged high-intensity exercise with better memory too. Scientists have found that six weeks of intense exercise— short bouts of interval training over the course of 20 minutes — showed significant improvements in high-interference memory, which, for example, allows us to distinguish our car from another of the same make and model.
According to the findings of the study, published in the Journal of Cognitive Neuroscience, memory performance of the study participants, who were all healthy young adults, increased over a relatively short period of time. The participants who experienced greater fitness gains also experienced greater increases in brain-derived neurotrophic factor, a protein that supports the growth, function and survival of brain cells.
Improvements in this type of memory from exercise might help to explain the previously established link between aerobic exercise and better academic performance, says Jennifer Heisz, an assistant professor in the Department of Kinesiology at McMaster and lead author of the study. For the study, 95 participants completed six weeks of exercise training, combined exercise and cognitive training or no training (the control group which did neither and remained sedentary). Both the exercise and combined training groups improved performance on a high-interference memory task, while the control group did not. Researchers measured changes in aerobic fitness, memory and neurotrophic factor, before and after the study protocol.
The results reveal a potential mechanism for how exercise and cognitive training may be changing the brain to support cognition, suggesting that the two work together through complementary pathways of the brain to improve high-interference memory. Researchers have begun to examine older adults to determine if they will experience the same positive results with the combination of exercise and cognitive training.
Also of interest is the finding of a new Australian-led study that aerobic exercise can improve memory function and maintain brain health as we age. Researchers examined the effects of aerobic exercise on a region of the brain called the hippocampus, which is critical for memory and other brain functions. Brain health decreases with age, with the average brain shrinking by approximately 5% per decade after the age of 40. Studies in mice and rats have consistently shown that physical exercise increases the size of the hippocampus but until now evidence in humans has been inconsistent. 
The researchers systematically reviewed 14 clinical trials which examined the brain scans of 737 people before and after aerobic exercise programmes or in control conditions. The participants included a mix of healthy adults, people with mild cognitive impairment such as Alzheimer’s and people with a clinical diagnosis of mental illness including depression and schizophrenia. Ages ranged from 24 to 76 years with an average age of 66. The researchers examined effects of aerobic exercise, including stationary cycling, walking, and treadmill running. The length of the interventions ranged from three to 24 months with a range of 2-5 sessions per week. Overall, the results – published in the journal NeuroImage– showed that, while exercise had no effect on total hippocampal volume, it did significantly increase the size of the left region of the hippocampus in humans. Interestingly, physical exercise is one of the very few ‘proven’ methods for maintaining brain size and functioning into older age.