Story highlights Fitness leads to longer life, researchers found, with no limit to the benefit of aerobic exercise

Comparing those with a sedentary lifestyle to the top exercise performers, the risk of premature death was 500% higher.

(CNN) We've all heard exercise helps you live longer. But a new study goes one step further, finding that a sedentary lifestyle is worse for your health than smoking, diabetes and heart disease.

Dr. Wael Jaber, a cardiologist at the Cleveland Clinic and senior author of the study, called the results "extremely surprising."

"Being unfit on a treadmill or in an exercise stress test has a worse prognosis, as far as death, than being hypertensive, being diabetic or being a current smoker," Jaber told CNN. "We've never seen something as pronounced as this and as objective as this."

Jaber said researchers must now convey the risks to the general population that "being unfit should be considered as strong of a risk factor as hypertension, diabetes and smoking -- if not stronger than all of them."

"It should be treated almost as a disease that has a prescription, which is called exercise," he said.

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