Exercise may be a kind of biological fountain of youth, according to new research showing older athletes tend to be much younger, physically, than they are in real life.

The study, involving participants in the coming Senior Olympics, found that the athletes’ fitness age is typically 20 years or more younger than their chronological age, The New York Times reports.

The findings are based on results of surveys of about 4,200 Senior Olympics competitors who completed an online fitness calculator.

Lead researcher Ulrik Wisloff noted that the athletes’ average chronological age was 68, but their average fitness age was 43.

“This is a massive difference,” Wisloff said. “I had expected a big difference, since these people have trained for years. However, I was surprised that it was this big.”