U.S. Masters Swimming Open Water Mix 5/10 255 Customizable to your specifications Hydrates and replenishes Zero stomach distress 100% All-natural www.sbrsportsinc.com SWIM WASH RINSE REPEAT Chlorine | Salt Water Out Hair & Body Care Available at AMAZON SwimOutlet.com & other loca�ons havior noted the apparent world record–holder covered 27 miles in 24 hours. The extent to which humans undergo exercise-induced neurogene- sis is less clear. In a 2017 meta-analysis published in NeuroImage, re- searchers concluded exercise may not increase overall hippocampal volume in people, but it does significantly increase the size of its left side. “Some studies have indicated that the left side is more responsive to lifestyle and environmental influences,” says lead author Joseph Firth, a senior research fellow at the University of Western Sydney in Australia. The practical significance of such a change, he acknowledg- es, remains mysterious. What likely plays an even more important role in brain health, Firth adds, is a change that doesn’t happen. “The benefits of aerobic exer- cise aren’t so much due to big gains in brain mass,” he says, “but rather are due to preventing the decline in brain size which occurs over time in older adults. The message here is if you want your brain to be at its happiest and healthiest throughout life, it’s worth adding in regular physical activity to your daily routines.” Geriatric benefits are great, of course, but it may leave younger adults wondering, “What’s in it for me now?” “It’s clear that exercise is associated with better cognitive functioning in older individuals,” says Yaakov Stern, professor of neuropsychology at the Columbia University Medical Center. “I wanted to see whether this was true for people in the younger range as well.” He and colleagues recruited 132 cognitively normal participants aged 20 to 67, all of whom were out of shape for their age. The investi- gators then randomly assigned them to one of two exercise conditions: half did aerobic workouts, half did stretching/toning exercises. They did these routines four times a week for six months. Besides assessing each person’s baseline aerobic capacity, the re- searchers used MRI to measure the thickness of their cerebral cortex, the most advanced, “intelligent” part of the brain. They then put them through a battery of cognitive tests to measure everything from pro- cessing speed to “executive function.” “Executive function is what it sounds like,” says Stern, explaining it’s what allows people to flexibly switch from one task to another, in- hibit distracting information, and grasp and manipulate information in the brain. Six months later, the researchers repeated all the same measure- ments to see what, if anything, had changed. The results, published in January in Neurology, showed aerobic exercise, though not stretching/ toning, had improved both VO2 max and executive function. These benefits occurred at all ages, including among the 20-somethings. The older a person was, however, the more improvement they showed. The executive function of 40-year-olds in the aerobic exercise condi- tion, Stern says, was comparable to what a normal 30-year-old would have. Among 60-year-olds, aerobic exercise helped their executive function perform as if they were a normal 40-year-old. “Sometimes find- ings that are statistically significant might not be meaningful in real life,” he says. “This convinced us their improvement was meaningful.” Not just performance was augmented by aerobic exercise. Fol- low-up MRIs showed the thickness of the cerebral cortex increased. “Although this increase in thickness did not correlate with the increase in executive function,” Stern says, “we viewed it a good indication aer- obic exercise was increasing brain health in general.” 35 ju l y- au gu st 20 19