[suprgeek]

We need to be wary of drawing the conclusions drawn here - the big tip-off is this sentence from the paper: "...Runners self-reported running for exercise three or more times per week for at least 30 minutes per bout and for at least six months prior to the study. "

A self-reported group of old runners can apparently walk more efficiently than a self-reported group of old walkers...but the runners were fit enough to run and sustain running to begin with!!

So older people who were fit enough to sustainably run for 6+ months were fitter than older folks who (were possibly not as fit) but choose to walk?

Horrible study...randomly assign fit older people to one or other group, let them run or walk for 6+ months - measure. Reverse the groups again measure.

[lightcatcher]

I think the study is assigning health benefits to "being a runner" rather than just "running". It's likely that the selected group of runners who had been running regularly for 6 months had been running regularly for much much longer, perhaps 10+ years. I'm definitely not an expert on the subject, but I don't know how many people are in good enough shape at age 60+ to start running, and I imagine most people running at age 60+ started running no later than their mid 50's.

The real thing you want to control for is the health of the runners and the walkers at the time the runners started running.