After last week's ultra-long post, I'm going to go short this week.
So today, without a lot of elaboration, we'll look at the latest scientific roundup on how activity affects knee joints.
An article on exactly that subject (just released online) is slated for March publication in the journal Medicine and Science in Sports and Exercise. What's more, it's a systematic review -- double gold in my eyes, because a systematic review aims to synthesize the evidence from a pile of existing studies.
Such a method reaches a more certain truth because, as we all know, individual studies can be confusing, as they sometimes contradict each other.
The article's researchers, led by Donna Urquhart, examined a total of 28 studies. Here are their conclusions (with my comments afterward). I've ordered the list from least to most interesting to build up a little suspense.
(1) There is limited evidence that there is a positive relationship between cartilage volume and physical activity.
Good news! And not surprising! (I suspect future studies will supply even more evidence). So this means people who are physically active have more cartilage in their joints than their lazier brethren.
(2) There is strong evidence that there is no relationship between joint space narrowing and physical activity.
At last, it's time to shut up the "tut tut" birds. You know the ones: they look at you askance and warn that with advancing age, running/cycling/playing basketball will just hasten the inevitable breakdown of your knee joints. For example, running will lead to deteriorating cartilage, and that means eventually the bones will be brought into closer proximity (joint space narrowing), until you're in danger of having bone scrape painfully on bone ...
Great Halloween horror story. But not necessarily true, it appears.
(3) There is strong evidence that there is an inverse relationship between cartilage defects and physical activity.
Hooray! In other words, the physically active have fewer cartilage defects. I'll go even further and predict what a systematic review may find in another 10 years or so: not only do physically active people have fewer defects, but more of those defects will be shown to improve over time than among the general population.
(4) There is strong evidence that there is a positive relationship between osteophytes and physical activity.
Okay, this is the one that should have surprised me greatly, except I had read this New York Times piece a while back. Osteophytes (or bone spurs) don't have to be bad; they can be of the good "protective" variety, it turns out. Spurs are sometimes just a way the knee adapts to the forces pulling on the joint. "There is ... evidence to suggest that osteophytes can develop without explicit injury to cartilage," according to this latest article.
Yet more good news ...
Time to get active!