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Your Feet Don't Have to Hurt
A Women's Guide to Lifelong Foot Care
By Suzanne M. Levine
St. Martin's PressCopyright © 2000 Suzanne M. Levine and Susan Jacoby
All rights reserved.
An Inside Look at Your Feet
Approximately one and a half million years ago, Homo erectus — the first of our primate forebears to walk upright — appeared on Earth. That historic transition, which freed up two hands for such useful tasks as manipulating tools and (hundreds of thousands of years later) lighting fires and planting crops, also placed unprecedented demands on the spine, legs, and feet. If you entered the new millennium with sore feet or an aching back, you have those very distant ancestors — the ones who decided it was more convenient and more fun to stand up instead of crouching on all fours — to thank and to blame.
With two appendages bearing the weight nature originally assigned to four paws, it's not surprising that the foot has turned out to be one of the most vulnerable parts of the human body. The anatomy of the foot and ankle has evolved in ways that make it possible for us to engage in a variety of activities far more mechanically complicated than the clumping around and lunging of our prehistoric relatives. Homo erectus definitely never went skateboarding, performed a pirouette on point, landed a triple axel on the ice, played mixed doubles, or skipped rope double Dutch style.
The Renaissance artist and scientist Leonardo da Vinci rightly described the foot as both a "masterpiece of engineering and a work of art." This complex and delicate anatomical marvel consists of twenty-eight bones, thirty-five joints, fifty-six ligaments, and thirty-eight muscles — all needed to support the body's full weight. Feet are the final recipients of every pound of pressure imposed by every upright activity.
For its flexibility, the foot depends on the equally delicate ankle joint, with an Achilles tendon that must contract properly to provide the "pushoff" power for every step. That the foot and ankle work as well and as dependably as they do is a tribute to their strength and adaptability; that they sometimes break down, sending painful messages that they're in urgent need of attention, is the logical (though not inevitable) outcome of the heavy workload they bear.
With our first, shaky toddler steps, we begin a journey of at least 150,000 miles — the average distance a man or woman travels on foot in the course of a lifetime. But that's just a ballpark figure. A professional athlete can accumulate more than 300,000 miles. An amateur weekend tennis player — or even someone who walks an hour a day for exercise — is also adding tens of thousands of miles to the "average" lifetime burden.
THE LOAD WE BEAR
With every ordinary step, we place pressure on our feet equal to at least one and a half times our body weight, and the load increases sharply with even low-impact activities like brisk walking and ballroom dancing. High-impact exercise and sports, such as jogging, step aerobics, basketball, and tennis, can triple or quadruple the pressure.
Patients often ask me why walking imposes a burden that's actually heavier than their body weight. Climb onto a bathroom scale, and you'll see why. You don't step firmly onto the scale, do you? If you're like most people, you approach the dreaded measuring instrument in as gingerly a manner as possible, planting your feet while hanging onto a railing or vanity table, avoiding any excess motion while you transfer your entire weight to the scale itself. Without actually thinking about it, you're aware that any motion inflates your total weight tally. If you weigh 130 pounds standing motionless, you'd register 195 on the dial if you could walk back and forth across a large scale, and 390 if you could run on the same surface.
Here's the simple biomechanical equation determining the pressure we bear: Body weight plus intensity of impact equal the force that causes true wear and tear on the feet. That's one reason why adults tend to decrease their level of activity — sometimes without even realizing what they're doing — as they gain weight. With a twenty-pound weight gain, we put thirty extra pounds of pressure on our feet even when we're only walking at a slow pace. Running transforms that twenty pounds into sixty — and dozens of bones, joints, ligaments, and muscles must absorb the added impact. Bearing this mathematical formula in mind, it's easy to understand why so many overweight people become discouraged and give up on exercise.
A FOUNDATION OF BONES
If you consider the inner structure of the foot, it will be easier for you to understand the complexity of the mechanism that springs into action with each step. As a podiatrist, I'm awed by the elaborate design, and I find it something of a miracle that such a complicated assortment of bones and joints doesn't break down more often.
Your foot is divided into three basic sections: the forefoot, which includes the toes and the ball of the foot; the midfoot, with an all-important arch that acts as a shock absorber for the entire body; and the hindfoot, with a heel and a triple joint linking your ankle to the arch in your midfoot. (See Figure 1.)
* Fourteen small bones are joined together to make up your five toes (phalanges). The big toe (hallux) is composed of two bones, while each of the other toes is made up of three bones.
Interestingly, studies have shown that the average adult's little toe is smaller today than it was a century ago. We're not born that way (like every other body part, feet are bigger today as a result of improved nutrition), but many adults — especially women — alter the shape of their toes by squeezing the forefoot into too-narrow shoes. In Western countries before the twentieth century, only the tiny upper class — the one segment of society that didn't have to stand on its feet to make a living and could count on riding rather than walking — wore constricting shoes.
* Also in the forefoot, two extremely tiny bones (sesamoids) lie buried at the base of the big toe. On X rays, the bones look like two eyeballs. The sesamoids are often ignored (some doctors even forget to mention them when they're talking about anatomy with patients), but they're extremely important: They act as pulleys for many muscles in the foot, and they also enable the big toe to move up and down. You've probably never heard of the sesamoid bones, but if you break one, you'll know it because you'll experience acute pain — and you probably won't be able to move your big toe.
* The five long bones leading to each toe (metatarsals) complete the forefoot. Look at the top of your foot, and you can easily see the shape of these bones beneath the skin. The bottom side of the metatarsal area is the ball of your foot.
* In the midfoot, five clumpy-looking, irregularly shaped bones (tarsals) make up your metatarsal arch (see Figure 2). This arch, linked to both the back and front of the foot by numerous muscles and the vital plantar fascia ligament — which connects the heel to the ball of your foot and is believed to be the strongest ligament in the body — provides the "spring" in your step. The higher the arch, the greater the spring.
Many people regard high-arched feet as "good" feet, but that judgment is based more on aesthetics — fashion photography has long exalted the high-arched woman — than on practical considerations. Like very low arches, extremely high arches have some drawbacks. For one thing, high arches place extra pressure on the heel, and that can cause stress fractures and pain in later life.
With age, the plantar fascia ligament loses some of its natural elasticity, causing most adults' arches — however high they were at birth — to flatten out to some degree. The shape of the tarsal bones, however, determines the original proportions of your arch.
* The hindfoot encompasses your heel (calcaneus) — the largest bone in the foot — and your ankle bone (talus). The uniquely flexible ankle joint (subtalus) between the ankle and heel bones is a miracle of anatomy — a hinge that enables you to move your foot up and down and from side to side. Increasing the complexity — and the possibility for injury — is the fact that the ankle and heel bones also form joints with separate arch bones (see Figure 2). We're all triple-jointed at the back of our feet.
SOFT TISSUE: CONNECTING AND PADDING
The soft tissues in your foot include muscles, tendons, and ligaments too numerous to describe in detail. Ligaments are fibrous tissues that connect bones and help to stabilize joints; without them, your bones couldn't "cooperate" and enable you to walk.
I've already mentioned the importance of the plantar fascia ligament, a mighty band of tissue that links the back and the front bones of your foot. Even a minor strain in that ligament can cause considerable pain — not only in the soft tissue itself, but also in the bones that aren't getting their accustomed help.
Another critical soft tissue is the Achilles tendon, commonly called the heel cord, which you've probably heard of because it figures in so many injuries to prominent athletes.
Running along the back of the ankle, the heel cord is actually an extension of two major calf muscles, and it attaches your heel bone to the muscles (gastrocnemius and soleus) that make it possible for you to stand on tiptoes.
You probably know the story of Achilles from Greek mythology. His mother tried to render him invulnerable by dipping him as a baby into the waters of the River Styx, but she overlooked one spot — the heel she was clutching when she immersed the rest of her son. Due to his mom's oversight, Achilles was fatally wounded by a perfectly placed arrow during the Trojan War. I've always wondered whether that myth developed because ancient Greek runners, like runners today, wanted an explanation for the acute pain they experienced at the back of their ankles when they ran too far too fast.
Even though we're not conscious of "rising" on our toes when we walk normally, we're actually doing it imperceptibly with every step. Ordinary activities like climbing stairs, or athletic moves like jumping, give our Achilles tendons a more strenuous workout. Running is actually a series of small jumps, though that's not obvious to the naked eye.
Because the Achilles tendon is involved in every move we make, it's responsible for some of the most serious, difficult-to-treat foot and ankle injuries. For a professional athlete, a ruptured Achilles tendon can become a career-ending injury. Even for those who don't make exceptional athletic demands on their feet, a torn Achilles tendon may require months of rehabilitation.
THE FOOT IN MOTION
Walking — unlike, say, playing tennis — doesn't have to be taught. So it's not surprising that healthy adults don't give much thought to what actually happens when they put one foot in front of the other.
"Gait cycle" is the term podiatrists use to describe the action of the foot from the beginning to the end of each step, from heel strike to heel strike. Whenever something goes wrong with your foot, the gait cycle is inevitably disrupted.
When you're standing still, the back and the front of the foot bear equal weight, and your plantar fascia ligament, supporting the metatarsal arch, is in a relaxed position. As you begin your step, the weight shifts, and you strike the ground with the outer, back part of the heel.
Then the weight rolls forward toward the ball of the foot and big toe (these shifts all occur in a split second), while the plantar fascia ligament flattens out below the arch to help absorb the downward pressure. This necessary sagging of the ligament and metatarsal arch, as your weight shifts toward the forefoot, is called pronation.
Immediately after the midfoot makes solid contact with the ground, the weight shifts in the opposite direction (a process called supination). The foot lifts up, and you rise on your toes and the ball (here's where the Achilles tendon does its job). You push off, with your large thigh muscles helping to propel the body forward. Meanwhile, the plantar fascia ligament is contracting and curving slightly upward into the metatarsal arch. With this part of the gait cycle completed, your other foot is poised to begin its heel strike.
Ever wonder why the heels of your shoes wear down unevenly on one side or the other? If your foot rolls inward too much as your heel strikes the ground, you have a built-in mechanical glitch called overpronation. In underpronation, a less common flaw, the feet roll too far outward.
Overpronation is more likely to cause physical problems, because more pressure is shifted to the ball of the foot — which already carries 60 percent of the weight-bearing load in a person of normal gait. The muscles in your feet, calves, and even lower back must then work harder to compensate for the extra load imposed on the front of your foot.
YOUR PERSONAL GAIT
Think about how easy it is to recognize someone you know, even when you're not close enough to make out her features, by the way she walks. The gait of many celebrities and prominent historical figures is as famous as their faces: I can easily summon up images of Marilyn Monroe's swivel-hipped glide, Adolf Hitler's stiff-legged, herky-jerky motion, Queen Elizabeth II's short, neatly spaced, ladylike steps, Elvis Presley's gyrating progress across a stage. Everyone has a unique gait, and anything that feels comfortable is normal.
But many people wind up with what doctors call an antalgic gait, a pattern of walking that develops, often unconsciously, in an attempt to compensate for a physiological problem and avoid pain. Some antalgic gaits are the result of lower back or knee problems. Look at old films of President John F. Kennedy, who suffered from severe back pain for most of his adult life, and you'll notice his stiff, almost unnaturally upright walk — an obvious (to a physical therapist) attempt to minimize the pressure on his lower spine. I don't know whether Kennedy had time to worry about his feet, but his style of walking invariably causes foot pain in midlife. The weight can't shift easily back and forth between the heel and the forefoot as it does in the automatic, natural gait of a pain-free adult.
Other antalgic gaits work in reverse: They cause back and knee problems because you're trying to avoid a sore spot on your foot. Even something as small as a corn or blister — not to mention more significant bony deformities like bunions — can lead to back trouble because you're twisting yourself into a shape nature didn't intend as you try to keep the weight off that painful part of your foot.
When a new patient walks through my door, one of the first things I do is observe her as she walks across the room. Without asking a single question, I can almost always tell where the pain is.
* * *
After this inside look at your feet and your walking style, I hope you'll have a new appreciation of the intricacy of the mechanism that keeps you moving through life — and of the reasons why even a small podiatric problem can cause such intense pain. Some of us have inherited a foot structure that predisposes us to certain problems. My extremely flat feet, for example, made it likely that I would develop bunions at a relatively early age. But the way we walk — our gait — is a product not only of anatomy but also of life choices. A police officer who's on her feet most of the day inevitably develops a gait different from that of an executive who spends most of her time sitting at a desk. A woman who generally wears three-inch heels sways and minces because her shoes don't allow her to take long strides. Footwear, not just anatomy, determines the fate of our feet.
If your feet are chronically sore, chances are you're suffering from a combination of problems: those buried within the inherited structure of your foot, and those you've created for yourself through inattention and misuse. Both types of foot troubles are eminently solvable, but both worsen with age unless you start to pay more attention to your feet as you move into your thirties, forties, and beyond.CHAPTER 2
The Life Cycle of the Foot
Our feet, like the rest of our bodies, have a natural life cycle. Although hereditary bone deformities may cause trouble even for toddlers, the overwhelming majority of foot problems in adulthood are the result of our failure to understand and make allowances for the normal changes that affect our feet as we age. While many of my patients describe the onset of excruciating pain as "sudden," I usually find, in the course of taking a careful history, that they've ignored minor foot pain for years.
Excerpted from Your Feet Don't Have to Hurt by Suzanne M. Levine. Copyright © 2000 Suzanne M. Levine and Susan Jacoby. Excerpted by permission of St. Martin's Press.
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