Short Term versus Long Term Gains in Working Memory Following Exercise
Research has established that exercise rapidly produces an improvement in memory function, within a matter of minutes. It is also the case that regular exercise slows cognitive decline with age and taking up exercise improves cognitive function in older individuals, when considered over the long term rather than immediately following exercise. Given that only a minority of the population in wealthier parts of the world, and particularly the older segment of the population, exercise to the degree recommended to best maintain health, these findings should probably be considered more a case of people doing themselves harm than a case of there being benefits to be obtained.
Today's research materials are interesting for directly comparing the short term and long term benefits of exercise to the operation of working memory in older people. The effect size is about the same, in that the same degree of improvement is observed immediately following exercise versus after a period of regular exercise, but the former benefit is very short-lived, while the latter benefit is sustained over time. The short-term benefit is also only observed in some people, and those differences correlated with structural differences in the brain. Is this all of any practical use at the present time, beyond being yet another recommendation to undertake more exercise? Probably not, but in the long term there is no such thing as useless knowledge.
New study suggests exercise is good for the aging brain
Researchers have found that a single bout of exercise improves cognitive functions and working memory in some older people. In experiments that included physical activity, brain scans, and working memory tests, the researchers also found that participants experienced the same cognitive benefits and improved memory, for a short time, from a single exercise session as they did in a sustained fashion from longer, regular exercise.
Previous research has shown exercise can confer a mental boost. But the benefits vary: One person may improve cognitively and have improved memory, while another person may show little to no gain. Limited research has been done on how a single bout of physical activity may affect cognition and working memory specifically in older populations, despite evidence that some brain functions slip as people age. Researchers wanted to tease out how a single session of exercise may affect older individuals. The team enrolled 34 adults between 60 and 80 years of age who were healthy but not regularly active. Each participant rode a stationary bike on two separate occasions - with light and then more strenuous resistance when pedaling - for 20 minutes. Before and after each exercise session, each participant underwent a brain scan and completed a memory test.
After a single exercise session, the researchers found in some individuals increased connectivity between the medial temporal lobe (which surrounds the brain's memory center, the hippocampus) and the parietal cortex and prefrontal cortex, two regions involved in cognition and memory. Those same individuals also performed better on the memory tests. Other individuals showed little to no gain. The boost in cognition and memory from a single exercise session lasted only a short while for those who showed gains, the researchers found.
The participants also engaged in regular exercise, pedaling on a stationary bike for 50 minutes three times a week for three months. One group engaged in moderate-intensity pedaling, while another group had a mostly lighter workout in which the bike pedals moved for them. Most individuals in the moderate and lighter-intensity groups showed mental benefits, judging by the brain scans and working memory tests given at the beginning and at the end of the three-month exercise period. But the brain gains were no greater than the improvements from when they had exercised a single time.
Acute Exercise Effects Predict Training Change in Cognition and Connectivity
Previous studies report memory and functional connectivity of memory systems improve acutely after a single aerobic exercise session or with training, suggesting the acute effects of aerobic exercise may reflect initial changes that adapt over time. In this trial, for the first time, we test the proof-of-concept of whether the acute and training effects of aerobic exercise on working memory and brain network connectivity are related in the same participants. Cognitively normal older participants (N=34) were enrolled in a randomized clinical trial. Participants completed fMRI resting state and a working memory task acutely after light and moderate intensity exercise and after a 12-week aerobic training intervention.
Functional connectivity did not change more after moderate compared with light intensity training. However, both training groups showed similar changes in cardiorespiratory fitness (maximal exercise oxygen uptake, VO2peak), limiting group-level comparisons. Acute effects of moderate intensity aerobic exercise on hippocampal-cortical connections in the default network predicted training enhancements in the same connections. Working memory also improved acutely, especially following moderate intensity, and greater acute improvements predicted greater working memory improvement with training. Exercise effects on functional connectivity of right lateralized fronto-parietal connections were related to both acute and training gains in working memory.