Knee injury while at rest.  Seemingly contradictory.   It has long been suspected that an active life and daily movement represent good ways to reduce your likelihood of getting arthritis. Now some researchers have finally looked at the numbers to see if this popular notion withstood statistical scrutiny. Their conclusion?

When they analyzed the step data from the pedometers, they found a strong link between participants’ activity level and knee health. Their results suggest 6,000 steps marks an important threshold: 70% of participants who developed knee impairments walked less than this amount while 70% of those who remained healthy walked more.

Using nothing more advanced than off-the-shelf fitness trackers, these researchers were able to study and control for a variety of factors in a population of about 2,000 people. Sure enough, the more active participants seemed considerably less likely to develop knee pain and other symptoms associated with this progressive disorder.  From a scientific standpoint, this makes sense.  Cartilage and the locomotion machine (i.e., body) function better when the ‘engine’ is kept warm.  Not turned off and allowed to collect dust; and not when the engine is ‘revved’ too high, wherein the parts fall into disrepair.  For example, the fascinating thing about cartilage is that cartilage requires, as a part of its normal maintenance, it’s use (such as with walking) to deliver the nutrients from the joint fluid into the cartilage structure.  It’s use actually prolongs it’s longevity!

Of course a cohort study like this cannot officially separate causation from correlation; it is possible, for instance, that people who walk fewer steps do so because they already have bad knees. Yet this study remains a tantalizing clue in support of the idea that sedentary lives can be injurious lives, and that we would all do better to move around more during our active years.