Many studies of exercise and health support the view that older people typically undertake far less exercise than they should. Exercise improves function and lowers mortality risk, and therefore the less active segment of the older population are only harming themselves. We evolved to be active throughout life, and we suffer when that is not the case. As researchers note here, the dose-response curve for exercise results in sizable benefits when moving from little exercise to some exercise, and diminishing returns with further increases. Evidence suggests that the optimal level is probably still somewhat more than the established 150 minutes per week, however.
The study followed 51 older adults, tracking their physical activity and fitness measurements. The participants performed tests specifically designed to measure cognitive functioning and underwent MRIs to assess brain functioning. They also wore a device that measured the intensity of the wearer's physical activity, number of steps taken and distance covered. The researchers assessed fitness through a six-minute walking test, during which participants walked as quickly as they could to cover the most distance possible within the time limit.
The brain is made up of a bunch of distinct networks. Different parts of the brain are active at different times. While one of these networks is active, the other should be shut off. If it's not, that's a sign that a person's brain isn't functioning as well as it should be. These networks are the key to being able to perform basic tasks in daily life, such as remembering important information and exhibiting self-control. But as people age, these tasks often become more difficult. This study was the first to examine how these networks interact with physical activity and fitness to impact how the brain functions.
"This paper is exciting because it gives us some evidence that when people whose brain networks aren't functioning optimally engage in physical activity, we see improvement in their executive function and their independence. Maybe just take the stairs on the way to work. Stand up and walk around a little bit more. That's where you get the most bang for your buck, not crazy, high-intensity exercise."