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Bad biomarkers, good knee news 

 •  • by Paul Ingraham
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Weekly nuggets of pain science news and insight, usually 100-300 words, with the occasional longer post. The blog is the “director’s commentary” on the core content of a library of major articles and books about common painful problems and popular treatments. See the blog archives or updates for the whole site.

Studies have shown that runners probably do not get more knee osteoarthritis than anyone else, which is a bit surprising: surely regular pounding wears out joints?

Researchers took a bunch of fancy pictures of the insides of knees before and after a marathon, using a new MRI technique that can detect early cartilage degeneration:

Runners showed elevated T1rho and T2 values after a marathon, suggesting biochemical changes in articular cartilage …

… the patellofemoral joint and medial compartment of the knee show the highest signal changes, suggesting they are at higher risk for degeneration.

Sounds bad, doesn’t it? Also, perhaps some biomarkers of trouble “remain elevated after 3 months of reduced activity” — but it’s arguable that those results were not actually statistically significant.

So, bad biomarkers in the knee after running, oh noes! But I actually see good news for knees here. It’s not surprising that a lot of running has an effect on joints in the first place, of course, and this data confirms that. But this data also shows that the effect is surprisingly minor, and that most knees recover, either mostly or completely, within three months. Which is very important information.

Stressfully loading a joint in itself is probably not a problem per se, and could even be healthy, stimulating, toughening — as long as you allow time to recover. It’s excessive loading without adequate recovery, AKA “overdoing it,” that is likely to be the real hazard for runners. I see this as (more) evidence that the average sane runner is not wearing out his or her knees (and also that runners who do get into trouble really, really need to rest and let their biomarkers simmer down).

“High-Field Magnetic Resonance Imaging Assessment of Articular Cartilage Before and After Marathon Running: Does Long-Distance Running Lead to Cartilage Damage?”
Luke et al. American Journal of Sports Medicine. Volume , Number . Jul 2010.

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