You're approaching age 45. You have a healthy body mass index. But are you more likely to sit on the couch and watch TV ..... or are you going for a run, riding your bike and generally staying active? The answer may make a difference in the future.

When it comes to fitness and athletics, even the most hardened enthusiasts realize at some point they're over the hill. Who knew the hill begins to crest by age 45?

A new study published last month in the Archives of Internal Medicine found that cardiovascular fitness in both men and women begins to decline sometime in the fifth decade of life and that the drop speeds up as you get older.

“The older athlete is redefining what normal aging is and what's possible for people who are middle age or older,” said Dr. Michael Joyner, an anesthesiologist with the Mayo Clinic in Rochester, Minn.

Joyner said athletes of all ages continue to improve record times because of better training methods, equipment and medical care.

“Your VO2 Max typically starts to decline in your 30s, but a highly trained athlete can delay that decline until they are in their later 30s or even early 40s,” Joyner said. “An average sedentary person loses about 10 percent per decade starting at about age 30, but for someone who is able to continue to train very hard into their 40s or 50s, they only lose about half that much, primarily due to the fact they continue to train hard.”

The Bulletin, by Markian Hawryluk, 11/12/09

Tags: Anesthesiology, athletes, Cardiology, cardiovascular fitness, Wellness