Non-runners often seem compelled to provide helpful advice to runners. A common refrain from such people is: "You know, all that running is going to wreck your knees." The runner with no history of knee problems can feel smug in the knowledge that there is no smoking gun that implicates treadmill running as a cause of osteoarthritis of the knee. For the runner with existing knee osteoarthritis or a history of significant structural injury to the knee, running may not be ideal.
Research focusing specifically on linear running has not found a cause-and-effect relationship with osteoarthritis of the knees. One such study, published in the "American Journal of Preventive Medicine" in 2008, compared aging long-distance runners to their non-running peers. Serial knee x-rays taken over 18 years failed to show any increased prevalence or progression of osteoarthritis among the runners. The authors concluded that otherwise healthy runners are not at increased risk for accelerated osteoarthritis of the knees as they age.
Running in Sports
Running in sports often calls for quick starts, stops and changes of direction. Sport-specific running potentially places greater stress on the knees than linear running and it certainly increases the opportunity for structural injury to the knees. Recognizing a link between sports participation and knee osteoarthritis, Swedish researchers sought to identify a specific cause for this association. After controlling for things like height, weight, smoking and occupation, they found that it was only the athletes who had sustained structural injuries to a knee that were at significantly greater risk of developing osteoarthritis in later years.
Overground vs Treadmill Running
Scientists studying biomechanics have noted small differences in the way people walk or run on treadmills versus overground. There is a tendency for treadmill runners to take shorter and faster strides when running at comparable speeds to overground runners. Overground runners extend their knees more fully and are more likely to land heels first compared to treadmill runners who land more on the middle of the feet. Vertical impacts known as "ground reaction forces" were found to be very similar between both running conditions in a study published in 2012 in the journal "Musculoskeletal Disorders." In terms of knee injuries or arthritis, there is no clear advantage or disadvantage to running on a treadmill.
Running After Injuries
Damage to ligaments or cartilage in the knee can result in changes that will accelerate the wear and tear with use. After recovering from such injuries, your doctor may clear you to return to running. Understanding that there is an association between prior injury and later osteoarthritis of the knee, you should start slowly with your treadmill work. Build up your speed and distance gradually. Be on the alert for any pain and swelling in the knee and promptly back off and consult your doctor if problems develop.
- American Journal of Preventive Medicine: Long Distance Running and Knee Osteoathritis A Prospective Study; Eliza F. Chakravarty, Helen B. Hubert, Vijaya B. Lingala, et. al.
- Scandinavian Journal of Medicine and Science in Sports: Knee Injuries Account for the Sports-Related Increased Risk of Knee Osteoarthritis; N. Thelin, S. Holmberg and A. Thelin
- Musculoskeletal Disorders: Comparison of Vertical Ground Reaction Forces During Overground and Treadmill Running. A Validation Study; Bas Kluitenberg, Steef W. Bredeweg, Sjouke Zijlstra, et. al.
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