A new study found that people who live a sedentary lifestyle are at risk for arthritis and other painful conditions at a younger age.

Denis Courtney, who has arthritis, got knee replacement surgery at just 41 years old. He says he originally injured the joint when he was 16 years old, playing soccer, and it got worse during his career as a construction worker.

Although Courtney has lived an active lifestyle, the new study shows many of his peers are suffering from the same conditions, but not due to injury.

"One of the reasons is obesity," says Dr. Nakul Karkare, an orthopedic surgeon. "Obesity has become an epidemic."

The international insurance company Bupa says more adults ages between 25 and 45 are getting treated for conditions traditionally seen in the elderly, like varicose veins, knee joint problems and back pain.

According to the study, more people are living a sedentary lifestyle: spending more time sitting at desks, watching television, playing video games or using smartphones and tablets.

People who show symptoms should seek early treatment, Dr. Karkare says.

"We have excellent evidence to show that early treatment not only decreases short term pain, but we also have excellent long term outcomes," he says. 

The study also shows that more younger adults are experiencing neck and back pain from constantly looking down at their phones.