Touted as an excellent form of exercise, walking is something we all do, and that most of us take for granted as an activity we need no training in. But of course we were trained, it was just at a time we no longer remember.
More than an exercise, it is a basic activity of daily living. We bear weight, we transport and we maintain our body’s equilibrium. The human gait cycle is more complicated than most of us appreciate, but perhaps that is because few of us take time to think about it. A normal gait supports our weight as we move with minimal energy expenditure. The lower limbs are adapted for stability rather than range of motion and that stability is achieved at the major joints of the lower limb through the use of strong ligaments and tight fitting bony surfaces rather than the expenditure of energy in the form of muscle contraction.
With each step we shift our weight to an ideal position supported by the surfaces of our bony joints.
The wide surfaces of the knee joints, and the arches of the foot and ankle bear the majority of the weight. The ligaments stabilize the joints with amazing strength providing support. The goal is to maintain an ideal center of gravity, and this is done instinctually.
The two main phases of gait are named stance and swing and the structures of the lower limb move differently during each. In stance phase the limb is weight bearing and in swing phase the limb is non-weight bearing. During stance phase, the pelvis moves over the thigh (femur), the thigh moves over the lower leg (tibia) and the lower leg moves over the foot. During swing phase, the motion is opposite, ie the thigh moves under the pelvis etc.
The muscles act to control the rate of motion and the size of each step. They accelerate and decelerate the bones to maintain the ideal center of gravity and support our weight as we move. Any deviation away from the instinctual pattern increases the work each limb must do at a higher energy expenditure.
If a muscle is weak, a ligament damaged, a bone misshapen or in the presence of neurologic disease, we subconsciously adjust our gait pattern to accommodate the dysfunctional part. Said another way, we limp. Most people think that if they have an injury limping will protect the impaired body part from further strain and this may be true but consider the rest of the body. For example, if an ankle is sprained, the normal compensatory instinct is to walk on the ball of the affected foot minimizing motion across the ankle joint. But walking on the ball of the foot, eliminating the part of gait when the heel hits the floor, causes excess strain on the calf muscles and hip, knee and toe joints and their ligaments. The time for each step on the injured leg is reduced and the healthy limb must bear weight longer than normal, thus straining the muscles and joints. And the muscles we do not use by walking on the ball of the foot get weaker.
When we limp, protecting the one injured part, we cause strain and misuse of many other portions of each limb. And this strain and misuse happen all the time, with every step. The risks of limping to the entire limb far outweigh any benefit limping might offer a single injured portion of a limb. The damage begins almost immediately so that even a single day of limping may cause substantial injury. When injured it is essential that we adjust the way we walk to maintain a normal gait pattern. Reducing the speed of our walking is one efficient way to restore a normal gait pattern. When this is not enough, using a cane or crutch to reduce our body weight can restore gait to normal.
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