To Prevent Shrinking Brain, Exercise in Your 70s Just a few walks a week can help: Study By Matt Cantor, Newser User Posted Oct 23, 2012 10:48 AM CDT 4 comments Comments Exercise in your 70s can help keep your brain from shrinking, a study suggests. (Shutterstock) (Newser) – To keep your brain fighting fit in your 70s, it seems that physical exercise beats mental workouts. Scientists found that in 638 people beyond retirement age, the most physically active subjects suffered less brain shrinkage over three years, the BBC reports; shrinking is associated with trouble thinking and remembering. Just a few walks a week helped, the study found. Seemingly brain-stimulating activities like crosswords, reading, and socializing, however, didn't do much to maintain brain size. Physically active subjects older than 70 showed less damage to their brains' white matter, which sends messages around the organ, as well as more grey matter. Experts aren't sure why exercise helps keep the brain healthy. It may have to do with the increased blood flow exercise brings the brain. "This research re-emphasizes that it really is never too late to benefit from exercise," says a scientist. "Whether it's a brisk walk to the shops, gardening, or competing in a fun run, it is crucial that those of us who can get active as we grow older."