Everyone and their grandmother seems to believe that running is bad for the joints, particularly the knees, even though a number of studies have shown no evidence of increased knee problems among typical runners. Today, the modern view holds that excess body weight and too little exercise are the big culprits underlying knee and hip arthritis.
Still, old beliefs die hard, while new imaging technologies promise better evidence of joint wear and tear. Then, there are special populations, like first-time marathoners who build their training to get ready for 26.2 miles. What would happen if you focused the new technologies on this group, which is widely thought to have high injury rates?
Research published in Knee Surgery, Sports Traumatology, Arthroscopy did just that. And it produced results similar to those seen previously: The runners' knees remained essentially unchanged by training for and completing a first marathon. The authors conclude: “High-impact forces during long-distance running are well tolerated even in marathon beginners and do not lead to clinically relevant cartilage loss.”
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The study included five men and five women who spent six months training for a first marathon, and then completed it. They averaged 40 years of age, with average BMI of 25.9, and had been running about 14 miles a week before beginning their marathon build-up. During marathon training, they averaged about 20 miles a week for six months.
Researchers from Germany’s Freiburg University Hospital measured the runners' cartilage volume and thickness before the training period, and one day after the marathon. They used three-dimensional quantitative MRI, a new and highly precise imaging technology, to look at the runners’ femur, tibia, and knees. “This method allows detection of more subtle changes in cartilage morphology compared to conventional MRI,” the paper states.
The results revealed very small differences in the pre-training and post-marathon images. The differences were judged not meaningful.
The Freiburg team thought they might find greater cartilage thickness in the post-marathon images, because low stress to the knee has been shown to reduce cartilage health. They wondered if high stress would have an opposite--and positive--effect.
It didn't. Because they observed only small cartilage changes, this hypothesis was not borne out. “Therefore, our study reinforces the assumption that cartilage cannot increase tissue mass as a result of mechanical stimulation,” the researchers write.
But neither does it harm the knee cartilage. The new study shows again that most runners need not worry about damaged joints. It appears to be a case of “Use it, or lose it.”
