How your feet work — and three steps for keeping them healthy
Standing and walking on two legs has many advantages over depending on four, six, or even eight, but it does mean we ask a lot of our poor two feet. They need to provide a steady base for the rest of the body to perch upon. They serve as shock absorbers as we walk or run, smoothing out the impact of landing with a force that exceeds our body weight. They act as levers that propel us forward — and occasionally in other directions.
An engineering feat
Each of our feet has 26 bones, one less than in our hands. The phalanges form the bendable (and breakable) toes. The calcaneus (pronounced kal-KAY-nee-us) makes up the heel. In between are the slender metatarsals and the blocky tarsal bones, which could be the work of a master mason the way they're ingeniously put together into an arch.
Over 100 different ligaments are needed to lash together this elaborate bonework and its 30-odd joints. Scores of muscles and tendons orchestrate the foot's movement. They enable the foot to move in several directions and help form its graceful, lengthwise arch.
All of this intricate architecture comes into play every time we take a step. In a normal, healthy gait, the heel hits the ground first. The calcaneus and a layer of fatty tissue underneath it absorb some of the impact. As the foot rolls forward on its outside edge, the intrinsic muscles of the sole of the foot give way a little and a band of tissue along the bottom of the foot, called the plantar fascia, stretches out. Then the weight moves to the ball of the foot and over the joints formed by the metatarsals and the first phalanges. Finally, we get leverage by pushing off on our big toes, while the Achilles' tendon lifts our heel.
Lucky for us, this happens without our having to think about it very much.
So what could go wrong? Plenty. Some people are born with irregularities like clubfoot (talipes equinovarus) or very high arches (pes cavus). In many cases, those problems can be corrected with surgery, particularly in young children.
There's another, larger group of us who have relatively minor defects. Age, weight, and time spent on our feet turn them into something more serious like flexible flat feet, overpronation (the tendency to walk or run along the inside part of the foot), or oversupination (walking on the outside edge of the foot).
Then there are the foot problems we bring upon ourselves by the shoe choices we make. Hammertoes and bunions are often a consequence of continually jamming five toes into narrow shoes. High heels are murder on the metatarsals and no kinder to the Achilles' tendon.
Even when we buy sensible shoes we make mistakes that our feet wind up paying for. We buy shoes that are too small, not realizing that as we age, our feet tend to grow by half a size or more because the ligaments and tendons stretch out. Even if the shoes are the right size, we often wear them too long, so the sole that helps with shock absorption is worn away.
So here's step one to having healthier feet: buy shoes that fit well with low heels and plenty of room for your toes — and replace them regularly.
Step two: stay trim, and if you haven't, work on losing some weight. Your feet won't be the only body part to benefit.
And step three: take your feet for a walk. The heel-to-toe motion strengthens and stretches your feet.September 2009 update