Running and Knee Health

When it comes to knee health, running often gets a bad reputation as being a cause for many ailments, the primary one being osteoarthritis.  However, as more research becomes available, these claims are found to be increasingly baseless, showing that running at reasonable volumes and intensities leaves the joint no worse for wear.  And according to some studies, possibly better than before!

What the research tells us:

There are many studies suggesting that running is not detrimental to the knees.  In one such study, 504 former collegiate cross country runners were surveyed to assess their levels of hip and knee osteoarthritis.  The follow up period for individuals was between two and fifty-five years, averaging twenty-five years.  Of those assessed, only 2% reported severe pain, and only 0.8% had surgery for their condition.  They compared these results to former collegiate swimmers, which had 2.4% reporting severe pain along with 2.1% having surgery (1).  The evidence from this study suggests that there is no association between moderate long-distance running and the development of osteoarthritis.  Additionally, it suggests that heavy mileage and the number of years running are not contributory to the future development of osteoarthritis.

That is all well and good, but those are former elite athletes!  How about when compared to people who do not run regularly? 

In another study, a group of male runners (who averaged 28 miles per week over 12 years) were compared to male nonrunners to assess a variety of factors.  The groups were compared in perceived pain and swelling in the knees as well as the hips, ankles and feet.  Additionally, radiologic exams were conducted to assess osteophytes (bony outgrowths in joints), cartilage thickness, and overall grade of degradation.  There was no statistically significant difference between either group for all measures, further suggesting that long-distance running is not associated with premature join degradation (2, 5).

A more recent systematic review conducted in Australia sought to analyze the effects of physical activity on the individual structures of the knee joint.  After analyzing 1,362 studies, the data suggested that there is an association between physical activity and osteophytes in the knee joint.  However, this is not necessarily a bad thing, and could possibly be an adaptation to the stimuli associated with exercise.  Additionally, the review states there is no strong evidence on physical activity narrowing the joint space from cartilage degradation.  In fact, there is strong evidence for an inverse relationship between physical activity and cartilage defects (3).  In other words, people who are active have stronger cartilage in the knees than those who do not.  This is further supported by a Swedish study, in which researchers gave people at risk of osteoarthritis a running program, and by the end showed improved biochemistry of the associated cartilages (5).

It is also worth noting that factors such as gender, education and mean exercise time do not appear to increase the chances of developing osteoarthritis in the knee.  Despite these findings, running is not an activity that everyone should participate in without the proper guidance.  Various factors such as genetic predisposition, higher than average BMI, and previous damage to the knee can all increase the chances of developing osteoarthritis (4).

What you can do to prevent damage to your knees?

If you are a runner and have not had knee problems, great!  Keep doing what you are doing.  

If you have had problems, here are some suggestions:

Try maintaining a stable BMI

Since it has been shown that having a high BMI while performing repetitive exercise can be a risk factor towards osteoarthritis (4), it is important to try having a consistent, average BMI.  Doing so will reduce the impact that your feet and knees take.  Did you know?  Depending on the intensity, running can create an impact of three to ten times a person's body weight! (6)

Watch your form

Improper biomechanics can place increased strain on the lower extremities.  Research suggests that running with a slightly forward-leaning trunk reduces stress on the patellofemoral joint (7, 8), which is the part of the knee where the thigh bone and knee cap meet.

Increase volume/intensity gradually

Among runners there is a training philosophy called the “10% rule”, in which during a training cycle weekly mileage does not increase by more than 10% from week to week.  The rule has validity, with one 2014 study showing that runners who followed this rule were less likely to become injured compared to a group that increased their mileage by 30% (9).

In conclusion:

If you are an experienced runner or someone who would like to start and have no underlying knee issues, do not fear that running will damage your knees.  That being said, always talk to a healthcare professional before making major lifestyle changes.  Train smart, and above all, enjoy running!

Sources:

1. Sohn, Roger S., and Lyle J. Micheli. “The Effect of Running on the Pathogenesis of Osteoarthritis of the Hips and Knees.” Clinical Orthopaedics and Related Research, no. 198, 1985

2. Panush, Richard S. “Is Running Associated With Degenerative Joint Disease?” JAMA: The Journal of the American Medical Association, vol. 255, no. 9, 1986, p. 1152.

3. Urquhart, Donna M., et al. “What Is the Effect of Physical Activity on the Knee Joint? A Systematic Review.” Medicine & Science in Sports & Exercise, vol. 43, no. 3, 2011, pp. 432–442.

4. Chakravarty, Eliza F., et al. “Long Distance Running and Knee Osteoarthritis.” American Journal of Preventive Medicine, vol. 35, no. 2, 2008, pp. 133–138.

5. Neighmond, Patti. “Put Those Shoes On: Running Won't Kill Your Knees.” NPR, NPR, 28 Mar. 2011

6. Elert, Glenn. “Force on a Runner's Foot.” E-World, 1999, hypertextbook.com/facts/1999/SaraBirnbaum.shtml.

7. Teng, Hsiang-Ling, and Christopher M. Powers. “Sagittal Plane Trunk Posture Influences Patellofemoral Joint Stress During Running.” Journal of Orthopaedic & Sports Physical Therapy, vol. 44, no. 10, 2014, pp. 785–792.

8. Teng, Hsiang-Ling, and Christopher M. Powers. “Influence of Trunk Posture on Lower Extremity Energetics during Running.” Medicine & Science in Sports & Exercise, vol. 47, no. 3, 2015, pp. 625–630.

9. Nielsen, Rasmus Østergaard, et al. “Excessive Progression in Weekly Running Distance and Risk of Running-Related Injuries: An Association Which Varies According to Type of Injury.” Journal of Orthopaedic & Sports Physical Therapy, vol. 44, no. 10, 2014, pp. 739–747.

Blog post by Robbie Papapietro.