Physical activity for aging: where's the context?

Reuters published an article this past Friday about a new study showing that older adults can maintain their balance if they exercise regularly, even if they start at retirement. Good news, maybe, but it really misses a lot of the context of the field by focusing on a single (observational) study.

There is a large body of literature suggesting that physical activity (by a number of definitions) for older people maintains function, prevents falling, does all kinds of good things. The problem is that most of these studies are observational, and don't account sufficiently for the fact that the folks who are exercising are probably already healthier to begin with, in ways that may be difficult to measure and correct for, and thus at lower risk of the outcomes measured by the studies. The current study is just another stitch in the fabric of that evidence, and suffers from the same weakness. There is, though, a recent study from the National Institute on Aging; it's a randomized trial that specifically addresses this potential weakness. Investigators administered a structured exercise intervention to elders at risk of losing their walking ability. The study confirmed the observational literature by showing that subjects who received the intervention were statistically significantly more likely to maintain their walking ability and their walking speed over the course of a year.

By the way, something tells me I may have written about this randomized trial here before, but I couldn't find the post, so if any of you sharp readers can find it, please let me know.