Some Britons have joints that appear to be more than a decade older than their age.
The findings are based on an online Joint Age Calculator, run by Seven Seas supplements.
Some 13,000 people took part, and one in five aged 25 to 34 had a 'joint age' over 50.
Osteopath Torben Hersborg, who helped create the calculator, said: "We must learn to look after our joints in the same way we know to look after our heart, weight or fitness. It requires work, but you reap the rewards."