Morning exercise boosts cognition in seniors
Moderate-intensity exercise in the morning improves cognition in older adults, according to a recent study.
Sixty-seven sedentary, overweight/obese, cognitively normal older adults (mean age, 67±7 years) completed three regimens of physical activity: uninterrupted sitting for 8 hours (sitting); sitting for 1 hour followed by 30 minutes of moderate-intensity walking, then by 6.5 hours of uninterrupted sitting (exercise + sitting); and sitting for 1 hour followed by 30 minutes of moderate-intensity walking, then by sitting interrupted every 30 minutes by 3 minutes of light-intensity walking (exercise + breaks).
Combining both exercise scenarios (with and without breaks in sitting), researchers observed improvements over uninterrupted sitting in working memory net area under the curve (AUC) z-score·hour with borderline significance (net AUC, 39; 95 percent CI, –2 to 79; p=0.06). A similar effect was observed for executive function (net AUC, 47; –5 to 99; p=0.08). [Br J Sports Med 2019;doi:10.1136/bjsports-2018-100168]
When physical activity conditions were taken individually, the exercise + breaks regimen was revealed to produce significant improvements in working memory over sitting (net AUC, +53; 3 to 102; p=0.04). In comparison, the exercise + sitting scenario resulted in a significant executive function benefit as compared with uninterrupted sitting (net AUC, +72; 9–135; p=0.02).
Neither exercise condition had such effects on other cognitive measures, such as attention, psychomotor function and visual learning.
“Our principal finding is that both activity conditions conferred some cognitive benefit across an 8-hour period, relative to uninterrupted sitting,” said researchers.
“However, the specific aspect of cognition that improves following exercise may be influenced by whether or not breaks in sitting are also performed,” they added. “This suggests that various patterns of physical activity may be used for the daily maintenance of brain health.”
Using venous blood samples subjected to laboratory testing, researchers also examined the effect of the exercise conditions on serum brain-derived neurotrophic growth factor (BDNF) levels. They found that uncorrected 8-hour net AUC ng/mL·hour marginal means were significantly higher in both the exercise + sitting (+471; 134–909; p=0.01) and exercise + breaks (+514; 175 to 853; p=0.003) regimens relative to uninterrupted sitting.
Correcting the analysis for change in plasma volume slightly reduced the between-group differences but did not attenuate statistical significance. There was also no significant difference in serum BDNF concentrations between the two exercise conditions.
“The increases in BDNF over 8 hours demonstrates an effective ‘whole of day’ strategy that could be repeated over weeks or months with implications for learning and memory,” said researchers, suggesting that this marker may also play a role in the physiological mechanism linking cognition and exercise, though requiring further validation in future studies.
“Future studies should focus on whether modifying the volume, frequency or intensity of active breaks can identify how best to maximize cognitive benefit,” they continued.
“Our findings have several potential implications,” they added. “First, it seems likely that prolonged uninterrupted sitting should be avoided to maintain cognition across the day in older adults. In addition, our findings may have implications for the design of longer-term exercise interventions seeking to improve aspects of cognitive performance.”