Whatever type of shoe you're buying, they can affect the health of your feet -- and far more.

"If your shoes aren't absorbing shock well, then your feet will, and then your knees, hips and back," says Dr. Jacqueline Sutera, a podiatric medicine and surgery specialist in New York City.

Some tips:

Consider the activity. Running and walking shoes are designed for forward motion, while tennis, basketball and cross-training types are meant to move from side to side.

Shop late in the day. Your feet are smallest in the morning, before swelling and gravity do their work. Your shoes should fit the bigger size.

Watch your size "number." Not every shoe company cuts its products the same way. Your size should be a starting point only; the best fit might be a half- or even full size away from usual.

Fit for your longest toe. Don't focus only on the "big" toe if your second toe is actually longer. Aim for about a thumb-width of distance between your longest toe and the end of a shoe.

Be careful buying flip-flops. They're not walking shoes. Flat, cheap flip-flops don't offer enough support for anything but short distances; thongs also force toes to overgrip to hold shoes in place. Overuse can cause serious injuries, including fractured bones. Invest in sturdier sandals -- thick rubber bottom, straps, arch support -- for walking.

Buy alternatives to heels. Any heel higher than 2 inches can cause problems, but if you do wear one, keep comfortable flats handy to give your feet breaks during the day. Don't wear the same-height heel every day, as doing so can damage tendons.


Study: Age might not affect running economy

Older runners might not have the speed of their younger counterparts, but they do have the same running economy, a study finds.

Running economy is a gauge of how efficiently the body uses oxygen at a given pace. Researchers used various tests to see how age affects factors of running economy in competitive distance runners.

The 51 male and female participants in the study were sub-elite distance runners who were grouped by age: 18 to 39, 40 to 59, and 60 and older. They were put through a variety of tests. Running economy was about the same for all groups at various treadmill speeds.

The study was published recently in the Journal of Strength and Conditioning Research.