Brain or muscles, what do we lose first?

From the age of 50, there is a decline not just in physical activity but also in cognitive abilities since the two are correlated. But which of them influences the other? Researchers used a database of over 100,000 people aged 50-90 whose physical and cognitive abilities were measured every two years for 12 years. The findings show that cognitive abilities ward off inactivity much more than physical activity prevents the decline in cognitive abilities.