Though the gym may be the coolest place to be seen working out, by far the quickest, easiest and cheapest aerobic is (literally) at your feet. Depending on your weight and rate, you can burn off around 100 calories during a 20 minute walk and it's a great way to clear your head focus your mind too. Now British researchers have discovered that continued muscle fitness in the legs is strongly associated with a better outlook for the aging in the brain.
The team at King's College London conducted a decade long study on 324 healthy female twins from the TwinsUK volunteer registry starting in 1999. The findings seem to suggest that simple things targeted to improve leg power — like an increase in time spent walking or running — may, in the long term, have a positive impact on cognitive aging. It's well known that a sedentary lifestyle is bad for your heart, circulation and weight but studies have also linked inactivity to depression too. The London study — published in the medical journal Gerontology — point to a direct link between leg-strengthening exercise and improved mental function.
Various cognitive processes — thinking, learning and memory — were measured at both the beginning and end of the study and it was found that leg power was a better predictor of change than any of the other lifestyle variables tested. The researchers measured various "health and lifestyle predictors" and, by comparing the outcomes for each twin, were able to account for any genetic factors in observed changes. "Everyone wants to know how best to keep their brain fit as they age," says Dr. Claire Steves, lead author of the study. "Identical twins are a useful comparison, as they share many factors, such as genetics and early life, which we can't change in adulthood."
The team found that, on the whole, the twin who displayed greater leg power at the beginning of the study showed fewer of the effects associated with aging when they were measured again after ten years. Previous studies have shown that physical activity can have a beneficial effect on the aging of the brain — A 2012 study using mice showed that exercising releases hormones which help nerve cells grow. In fact, in that study, physical activity helped sharpen cognitive ability more than any other kind of stimulus.
We also already know that keeping to a healthy diet can benefit both mind and body. This year, further study from Europe delivered results that suggested the right balance of omega-3 fatty acids, vitamins and minerals can help reduce the risk of depression in the long term. There, researchers at the University of Las Palmas found a direct link between good physical health and a positive effect on mental health which seems to mirror the idea that what's good for the body is good for the brain.
The new study is thought to be the first to show a specific link between power — force and speed — in the lower limbs and a positive cognitive effect on normal, healthy individuals. The legs contain the largest muscles and so they often play a major role in exercise. Leg exercise is also generally the easiest and, as such, they are of particular relevance for muscular fitness. "It's compelling to see such differences in cognition and brain structure in identical twins, who had different leg power ten years before," says Steves. "It suggests that simple lifestyle changes to boost our physical activity may help to keep us both mentally and physically healthy."
The researchers point out that more studies are needed to better understand the relationships between leg power, aerobic capacity and the brain and how to correctly assess the exact impact on brain structure and cognition. Other details, such as age-related changes in immune function, blood circulation or nerve signaling, need to be factored into the equation, the team says. Only female participants with an average aged between 43 and 73 took part in this study so further studies would also be needed to see how older or male populations are affected.