If you're trying to get in shape, lose weight, and improve your cardiovascular system but are afraid that should you start running your knees will get arthritic...don't worry about it. Yet another study demonstrates that risk of OA in joggers is lower than in those who lead a sedentary lifestyle. So put down the remote, get off the couch, and go discover the benefits of getting fit regardless of your age!

Knee OA Risk Lower in Joggers

Published: Nov 17, 2014 | Updated: Nov 17, 2014

By Kate Johnson

BOSTON -- People who run at any time of life have lower rates of knee pain and osteoarthritis (OA) compared with nonrunners, according to cross-sectional analysis of data from the Osteoarthritis Initiative (OAI).

"Based on our findings, clinicians can say to those who don't already have osteoarthritis, that running does not appear harmful to the knee from the perspective of developing radiographic evidence of knee OA and knee pain. These people should not be discouraged from running," lead investigator Grace Hsiao-Wei Lo, MD from Baylor College of Medicine in Houston, told MedPage Today.

"I was mostly trying to show that running wasn't harmful to the knee. It was a nice surprise to find that it might actually have positive benefits for the knee," she added.

The study included 2,683 subjects, mean age 64.5 years, with a mean body mass index (BMI) of 28 kg/m².

All participants had knee radiograph readings, and knee pain was assessed by questionnaire.
Roughly 29% (n=776) of the subjects reported that they had run at some time in their lives.

"We asked specifically for people to think back over their lives between the ages of 12 to 18, 19 to 34, 35 to 49, and then greater than or equal to 50," explained Dr. Lo during a press conference at the annual meeting of the American College of Rheumatology.

"During each of those age ranges we asked people to indicate the top three activities that they participated in [more than 20 times in life]. If they indicated running as one of those activities we indicated them as a runner for that particular time frame."

The researchers looked at the relationship between running over a lifetime and knee pain, radiographic osteoarthritis (ROA) of the knee, and symptomatic ROA of the knee, "meaning that people had to have both pain and evidence of radiographic OA on the same knee," she said.

They found that people who ran at any time of life had a lower prevalence of both frequent knee pain and symptomatic ROA compared with nonrunners (35.0% versus 41.6%, odds ratio 0.87; and 22.8% versus 29.8%; OR 0.83, respectively) -- differences that remained statistically significant after adjusting for age, sex, and BMI, she said.

There is controversy regarding whether habitual running is beneficial or harmful to the knee because chronic, mechanical overloading could potentially physically damage structures within the knee, said Dr. Lo. "But, alternatively, runners have a lower BMI which we know is protective of knee OA."

The question of whether or not running increases the risk of OA is particularly relevant because the physical activity guidelines from the Centers for Disease Control recommend 75 minutes per week of vigorous aerobic activity such as running, she said.

Most previous studies looking at the relationship of running and knee OA have focused on elite male runners and are therefore not generalizable, she noted.

"There's really little data out there addressing this question in the general population and so Dr. Lo's study is, I think, one of the first to look at this question in a population-based study," said moderator Rob McLean, DSc, MPH, an epidemiologist at Harvard Medical School in Boston.