Is running bad for your knees?

Humans are bipedal creatures designed to move forward on two feet. It seems odd that the most efficient way of moving our bodies from point A to point B would be bad for our joints, yet running receives a lot of criticism. Running has historically been criticized by the general public and even some medical professionals for “putting too much stress on the joints” leading to pain, injury, and osteoarthritis.

Evidence does not support that running is associated with increased risk of osteoarthritis (OA). There is evidence that suggests decreased physical activity is associated with increased incidence of osteoarthritis.

Over the past century our culture has become more and more sedentary.  A recent study¹ found the prevalence of knee osteoarthritis among individuals over 50 years old in the early industrial era (late 1800s to early 1900s) was 6% compared to 16% of individuals in the post-industrial era (late 1900s to early 2000s).  After controlling for age and BMI, the data indicates the prevalence of knee OA has increased by 2.1-fold over the last century.

Osteoarthritis is not a disease of wear and tear. Sedentary lifestyles, obesity, and chronic inflammation are more likely to contribute to developing osteoarthritis than running. 

This progressive disorder is characterized by inflammation and loss of cartilage that lines the ends of bone. Running is an effective form of activity to control weight, manage BMI, and reduce systemic inflammation. The repetitive movement and force within the joint stimulates repair and maintenance mechanisms to maintain healthy cartilage. Running may actually decrease your risk of developing OA, while inactivity may increase your risk. This does not account for trauma disrupting ligaments or cartilage that occurs with running.

The cartilage in our knees functions as a shock absorber. Articular cartilage does not have a blood supply. Rather it gets its oxygen and nutrients from the surrounding joint fluid. Repeated compression of the joint allows water to flow in and out of the cells delivering nutrients to the tissue. The weight that bears down on your joints when you exercise forces water molecules out of the cartilage like a sponge. When the weight is lifted, water flows into the cells bringing oxygen and nutrients the joint.

Still think running is bad for your knees?

Let’s look at the research that indicates running does not cause damage to the knees or increase risk of developing osteoarthritis.

A study by Eliza⁴ compared 45 long distance runners to 53 non-runners with a mean age of 58 over the span of 20 years. Radiographic evidence showed no difference in prevalence of knee osteoarthritis between the two groups.

Another study by Kessler⁵ looked at the short-term effects that long distance running has on cartilage and meniscus. Cartilaginous volume was measured by MRI in 48 runners before a 20 km run, immediately after the run, and after a one hour recovery. Decrease in cartilage volume was found immediately after the run but was no longer significant after one hour. The recovery of cartilage and meniscal volumes suggests that these tissues are able to adapt to the loads caused by running.

Krampla⁷ conducted a 10-year study looking at the changes in knee joints of marathon runners. No adverse long-term consequences were observed in six of the seven active runners at the 10- year MRI follow up.

A longitudinal study by Sohn⁸ compared 504 former college cross-country runners with 284 former college swimmers. The subjects were observed for an average period of 25 years.  They found that moderate long-distance running (average 25.4 miles per week) was not associated with higher incidence of osteoarthritis of the hip or knee.

A study by Kujala⁹ looked at the prevalence of knee OA among former athletes of varying sports. The prevalence of knee OA determined by radiographic examination was 3% in shooters, 29% in soccer players, 31% in weightlifters, and 14% in runners. This study does not control for knee joint trauma contributing to the development of osteoarthritis; however, it does not support the idea that running is worse for your knees than other forms of physical activity.

Lane¹⁰ performed a study including 33 matched pairs of long-term, long-distance runners and non-runners over the age of 50. The study showed no difference in the incidence of osteoarthritis in runners and nonrunners. The results remained the same at a 9-year follow up.

 Our bodies are designed to move, and our joints are designed to withstand the demands of running. The repetitive movement that occurs with running facilitates the delivery of nutrients to the knee joints and stimulates repair mechanisms to maintain healthy cartilage. There are limitless forms of physical activity to optimize health and fitness. Running may not be for you, but please stop telling other people it is bad for them. The evidence indicates running is not bad for your knees and does not increase your risk of developing osteoarthritis.

If you are interested in running and do not have previous experience, come see one of our Doctors of Physical Therapy for a complete movement analysis. We will assess your mobility and strength and provide you with the tools to safely begin a running program. 

If you run, you are a runner. It doesn’t matter how fast or how far. It doesn’t matter if today is your first day or if you’ve been running for twenty years. There is no test to pass, no license to earn, no membership card to get. You just run. – John Bingham

Written by Hannah Sweitzer, DPT, OCS

References

1. Ian J. Wallace, Steven Worthington, David T. Felson, Robert D. Jurmain, Kimberly T. Wren, Heli Maijanen, Robert J. Woods, Daniel E. Lieberman. Knee osteoarthritis has doubles in prevalence since the mid-20th century. Proceedings of the National Academy of Sciences Aug 2017, 114 (35) 9332-9336; DOI: 10.1073/pnas.1703856114
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7. Krampla, W.W., Newrkla, S.P., Kroener, A.H. et al. Changes on magnetic resonance tomography in the knee joints of marathon runners: a 10-year longitudinal study. Skeletal Radiol 37, 619–626 (2008). https://doi.org/10.1007/s00256-008-0485-9
8. Sohn RS, Micheli LJ. The effect of running on the pathogenesis of osteoarthritis of the hips and knees. Clin Orthop Relat Res. September1985:106 –109
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