Turns out, muscular strength, measured by handgrip, is an indication of how healthy our brains are.
Using data from the 475,397 participants from all around the UK, a research showed that on average, stronger people performed better across every test of brain functioning used.
Tests included reaction speed, logical problem solving, and multiple different tests of memory.
The study from the NICM Health Research Institute and Western Sydney University showed the relationships were consistently strong in both people aged under 55 and those aged over 55.
"When taking multiple factors into account such as age, gender, bodyweight and education, our study confirms that people who are stronger do indeed tend to have better functioning brains," said researcher Joseph Firth.
The study also showed that maximal handgrip was strongly correlated with both visual memory and reaction time in over one thousand people with psychotic disorders such as schizophrenia.
He said: "We can see there is a clear connection between muscular strength and brain health. But really, what we need now, are more studies to test if we can actually make our brains healthier by doing things which make our muscles stronger - such as weight training."
He added, "The study raises the strong possibility that weight training exercises could actually improve both the physical and mental functioning of people with these conditions."
The findings are published in Schizophrenia Bulletin.