All over the map

Middle Daughter spent a year studying abroad in Senegal. One of the things she noticed was that the American and Senegalese students both bought the same kind of sandals, but the Americans wore through theirs much more rapidly. She attributed this to a difference in walking stride--the Senegalese women tended to walk with the foot more flat, so that it landed more on the ball, or even evenly, while Americans tended to hit heel first.

Since knee problems have been a live issue in our home, I wondered if one's stride had something to do with stress on one's knees.

The first question is epidemiological: Is cartilage deterioration more common here than there? Unfortunately that's not easy to answer, thanks to radically different health care systems and reporting. The rate of meniscus repairs will be a lot lower there, no matter the relative need.

So, off to sports medicine. You name it, somebody claims it. Heel-first is 6% more energy efficient, and early hominid footprints tell us they did it too. Ground force vs time plots are distinguishable, but the curves don't show (for me, anyway) a true winner. Runners run using the front of their feet because the angle of a runner's body wrt the ground demands it.

Barefoot is better. Or maybe it doesn't make any difference. Or it depends on the footwear.

You'd think intuitively that the stress on your knee would be less when your foot flexes with impact rather than when you strike hard with your heel. But it seems that the heel pad cushions the blow well enough to make it pretty much a wash. Unless it doesn't. Running is good for your joints, possibly simply because it keeps you leaner and stronger. (Apples to apples comparisons are hard here.)

Combing out the folks who want to sell you something or make a name for themselves, and just looking at the studies, is taking more time than I thought it would.

I think I'll try to take a walk using a different stride and see how it feels. I predict "awkward." Maybe it's all cultural, and all a wash--just so you don't overdo or underdo things.