Read an Excerpt
the yoga back book
By Stella Weller
Red Wheel/Weiser, LLCCopyright © 2013 Stella Weller
All rights reserved.
Before driving a car or using a piece of machinery, people usually acquaint themselves with the way it works. This allows them to operate it intelligently and therefore safely. The human spine, which is perhaps more sophisticated in its design than most machines, should be similarly considered.
A basic understanding of how the spine is constructed and how it functions is therefore a vital first step towards acquiring and maintaining a trouble-free back. This chapter represents that important first step. Spend a few minutes reading it from beginning to end. The time you invest in doing so will be rewarded; it will equip you to care for your back with insight and wisdom.
Functions and Structure
The spine supports the head and about 90 per cent of the weight of the human body in an upright position. It is mechanically balanced to conform to the stress of gravity and to permit movement from place to place, as well as to assist in purposeful movements.
The spine prevents shock to the brain and spinal cord during activities (such as running and jumping) through its curves and intervertebral discs, about which more information will be given later. It protects and houses the spinal cord. It provides attachment for many powerful muscles and it forms a strong posterior boundary for the body.
Known also as the spinal or vertebral column, the spine is composed of 33 bones (vertebrae; singular, vertebra) with a pad of cartilage, or gristle (intervertebral disc) in between every two bones (Fig. 1, Fig. 2 and Fig. 3). This disc buffers the vertebrae against shock during activities such as running, jumping or driving on bumpy roads.
The disc has a tough elastic shell composed of crisscrossing fibres. Inside it (the nucleus) is a soft substance with the consistency of jelly. The upper and lower surfaces of the disc have a cartilaginous layer known as an end plate. This acts somewhat like a sieve between the disc and the bone.
Discs have no blood supply; they depend on a process of diffusion through the end plates for their nutrition. When we are resting or sleeping, the discs suck in water and other nutrients. When we move about or exercise, compression squeezes fluids out and expels wastes. A sensible balance of exercise and rest is therefore crucial in maintaining the health of the intervertebral discs.
All individuals can expect degenerative changes in the discs. Between the ages of 20 and 30, maximum development of the discs has occurred and the water content is maximal-about 80 per cent. This lessens with age. With a healthy lifestyle, however, it is possible to keep the discs from drying out, and to preserve a good balance between fibre and fluid, even into advanced age.
You may also think of the spine as being composed of a number of functional units. Each unit (Fig. 2) consists of two segments: an anterior (front) portion which may be considered a hydraulic, weight-bearing, shock-absorbing structure comprising two vertebrae with a disc in between them, and a posterior (back) portion which may be thought of as a guiding mechanism. This includes three projecting pieces of bone: two projecting sideways and one rearward. You may be able to feel these as 'buttons' down the middle of your back. These processes provide for the attachment of ligaments and muscles.
In addition, the rear portion of the vertebra has two upper and two lower surfaces called facets. The lower facets of one vertebra glide along those of the vertebra below. The facets thus guide and limit the motion of one vertebra relative to its neighbouring vertebra.
The articulated posterior processes of the vertebrae form a canal which houses and protects the spinal cord. This is a bundle of nerve fibres connecting the brain with all parts of the body, and which carries messages to and from the brain.
On each side of the spine, between every two vertebrae, are tiny openings for the passage of nerves branching from the spinal cord.
Ligaments and Muscles
Strengthening the joints formed by the vertebrae and their intervening discs are ligaments-tough fibrous bands of tissue-running behind and in front of them along the entire length of the spine.
Reinforcement is also provided by the back muscles which help to control forward bending, and indirectly by the abdominal ('tummy') muscles which give a counterbalancing effect and help to prevent extreme backward bending.
It is worth noting that although the abdominal muscles are not directly attached to the spine, their strength and tone are crucial to the overall health of the back.
The space between the bones, tendons, ligaments and muscles of the back are filled with material known as connective tissue. Much of this filling is composed of a protein substance known as collagen. In fact, collagen accounts for about 30 per cent of total body protein. It is a sort of 'cement', which binds cells together. It is the key to the relationship between nutrition and spinal health. It acts as a transport medium, carrying nutrients from the bloodstream to the muscles and ligaments, and conveying wastes to the bowel and skin for elimination.
The chief functions of connective tissue in the back are: to bind tendons to bones and buffer muscles and ligaments to help to maintain resilience and strength; and to act as a medium of transport carrying oxygen and nutrients to spinal structures and removing wastes.
With your mind's eye now, try to see the spinal column from the side (laterally). You will note four curves (Fig. 3): in the neck (cervical) region, one that is convex towards the front (lordosis); in the chest (thoracic) area, one that is convex towards the rear (kyphosis); at waist level (lumbar spine) another arch that is convex towards the front, and at hip level (sacral area) another arch that is convex towards the rear. These curves transect the plumb line of gravity in order to maintain a state of balance.
The Pelvic Ring
The spine is balanced on an undulating pelvic base known as the pelvic ring (sometimes pelvic girdle). (Fig 4.). This is the human body's chief weight-transmitting structure, connecting the upper body to the legs. It consists of the sacrum at the back, and two innominate (hip) bones which are connected to the femurs (thigh bones). Together, these bones form five joints: two sacroiliac joints at the base of the spine; two hip joints where the hip bones connect with the legs, and the symphyis pubis where the two hip bones join in front.
A key feature of the pelvic ring is its strong ligamentous support, which is especially important in weight bearing.
During normal standing or sitting, the ligaments of the sacroiliac joints and the pelvic ring are somewhat loose. When weight bearing occurs, however, the pressure exerted down through the spinal column causes the sacroiliac ligaments to tighten. This tightening alters the position of the pelvic ring from a loose, or neutral structure to one that makes for greater stability.
A second key characteristic of the pelvic ring is that its degree of tilt determines the quality of the curves in the spinal column above. Any change in the angle of the sacral portion of the pelvis will influence the curves of the spine above, thus determining posture. If the pelvic ring is in a balanced position, the spinal curves will be proportionately balanced and the posture safe. If, however, the pelvic ring is abnormally tilted, poor posture will result and the spine will consequently be more vulnerable to injury and pain.
Good posture and smooth movement and rhythm require good coordination between nerves and muscles, good flexibility of tissues and adequate functioning of all joints involved.
The chief back muscles are as follows:
The erector spinae muscles form two columns, one on each side of the spine. They extend the spine and keep the trunk erect.
The latissimus dorsi is a broad, flat muscle lying over the lower part of the chest and loins (between ribs and hip bones). It draws the upper bone of the arm (humerus) down and back, and rotates the arm inwards.
The gluteal muscles, which form the buttocks, raise the trunk from a stooping to an erect position. They are also involved in leg motions.
The sling muscles (hip flexors) connect the transverse processes of the spine on the inside (the projecting pieces of bone mentioned in the section 'Spinal Units'), cross the pelvic ring and attach to the thigh bones just below the hips. They are very important in the maintenance of upright posture.
The lateral muscles are situated between the ribcage and the pelvic ring. They extend from the lowest ribs to the hip area and legs.
Muscles forming secondary supports to the spine are: the quadriceps (thigh muscles), which run down the front of the thighs and insert into the kneecaps or patellae, and serve to extend the knees; and the hamstrings, which are located at the back of the thighs, passing from the pelvic ring and inserting into the bones of the lower legs (tibiae and fibulae). The hamstrings flex the knees and extend the thighs.
Both sets of muscles-quadriceps and hamstrings-contribute to the tilt or balance of the pelvic ring and so are important to good posture.
The abdominal muscles, which will be dealt with in chapter six, basically extend from the breastbone (sternum) to the symphysis pubis, on each side of the midline. Although thin, these muscles give extremely important support to the spine. They operate at a distance and so provide leverage.
Postural patterns are influenced not only by lifestyle but also by genetic and early environmental factors. Without conscious, sustained effort, faulty postures can become permanent.
There is no ideal posture, since people come in all shapes and sizes. The ideal posture for you is one in which your back is subjected to the least possible strain and in which the normal graceful curves of the spine are maintained.
The key to good posture is fitness. If you keep your muscles well conditioned, you stand a good chance of acquiring the posture that is correct for you, particularly if you complement this with a balanced mental and emotional state. This is the essence of the yoga approach.
Dr Bess Mensendieck, a sculptor turned physician, has remarked that correct posture, and freedom from pain due to faulty posture, can be acquired only when all muscles are used in accordance with their anatomical functions and with the laws of body mechanics. She has further noted that the primary exercise needed to achieve these states is the practice of correct postural habits during normal daily activities. No daily half-hour exercise session alone will produce good posture if muscles and joints and related structures are not used properly the rest of the time.
A well-aligned vertebral column when we are upright or sit or lie down imposes the least strain on the spine. It is also an important prerequisite for the harmonious functioning of the nervous system, which is hinged on the backbone and the spinal cord, and for the free expansion of the chest to permit proper breathing. If we can maintain natural physical equilibrium when both sitting and standing, we minimize strain on the back muscles and facilitate harmonious distribution of the body weight along the 132 articulations of the vertebral column.
In summary, your posture is determined by the way you hold each part of your body, from head to toes. Your posture affects your breathing, indeed your health in general-both physical and emotional-and the image your present to the world.
In order to relieve stress on the lumbar spine, a natural lumbar curvature (at the small of the back), good balance and flexibility must be maintained at all times. The natural lumbar curvature is maintained through pelvic tilt (assisted by tightening abdominal and buttock muscles). The position distributes weight evenly down through the spine allowing the strong leg muscles to bear the weight.
Now that you have a basic understanding of the structure and function of the spine, you will readily appreciate the principles of good body mechanics which follow and the importance of maintaining the normal spinal curves.
Good posture when sitting puts the pelvis in a neutral position, that is, neither tilted backwards not tilted forwards (remember that posture is controlled mainly from the pelvis).
The spine should be supported along its natural curve. The height of the seat should be such as to place the knees level with, or higher than, the hips (Fig. 5).
Figures 6 and 7 are examples of poor posture in sitting. In Fig. 6 the pelvis is tilted backwards. This flattens the normal curve of the lower spine, stretching ligaments and eventually producing pain.
In Fig. 7 the pelvis is tilted forwards, thus distorting good posture in much the same way as prolonged standing does. This, too, can lead to back strain and pain.
The Easy Pose
One excellent way to sit is in the yoga Easy Pose (Fig. 8). It provides a stable base, encourages you to hold your spine naturally erect and promotes relaxation of the back muscles. It brings into play the sartorius, or tailor, muscles which lie across the thighs, from about the front of the hip bones to what we know as the shin bones. These are the muscles used in bending the legs and turning them inwards.
Here's how to do the Easy Pose.
1 Sit with your legs stretched out in front.
2 Bend one leg and place the foot under the opposite thigh.
3 Bend the other leg and place the foot under the other bent leg.
4 Rest your palms quietly on the respective knees or place them upturned, one in the other, in your lap.
5 Maintain this posture as long as you comfortably can, breathing regularly, and keeping your body relaxed.
If your knees do not touch the surface on which you are sitting, do not be discouraged. They eventually will as your joints become more flexible and your ligaments more elastic.
The Japanese Sitting Position
Here's another position that encourages good posture in sitting (Fig. 9).
1 Kneel down with your legs together and your body erect but not rigid. Let your feet point straight backwards.
2 Slowly lower your body to sit on your heels. Rest your palms quietly on the respective knees. Sit tall and breathe regularly. Keep as relaxed as you can.
If at first your heels cannot bear your weight, place a cushion between your bottom and heels, and hold the position only briefly. As your knees and ankles become more flexible and your body more conditioned, you will be able to sit in this posture for a longer time.
One quarter of the human race habitually take weight off its feet by squatting. A deep squat position for work and rest is used by millions of people in Africa, Asia and Latin America.
Squatting reduces any exaggerated curve of the lower spine, thus lessening tension in spinal muscles and ligaments. It reduces pressure on the spinal discs. As a result, the back is both strengthened and relaxed, and back discomforts are minimized. Squatting is, moreover, excellent for strengthening the ankles and feet.
The Squatting Pose
1 Stand with your legs comfortably apart. Distribute your body weight equally between your feet. Breathe regularly.
2 Slowly bend your knees, lowering your bottom until you are sitting on your heels. Relax your arms for maximum comfort (Fig. 10). Hold this posture as long as you can, breathing regularly.
3 Resume your starting position. Rest.
If you have varicose veins, you would do better to practise the dynamic version of the Squatting Pose which follows, rather than holding the squat for any length of time.
The Squatting Pose-Dynamic version
1 Stand with legs apart and arms at your sides. Inhale and slowly raise your arms to shoulder level as you simultaneously raise yourself on your toes. (If you have difficulty keeping your balance, use a stable prop for support.)
2 Exhale and slowly lower your arms as you lower your body into the squatting posture (Fig. 10).
3 Without holding the posture, come up again on tiptoe. Repeat the up-and-down movements in smooth succession as many times as you wish. Relax afterwards.
This version of the Squatting Pose gives a gentle, therapeutic massage to the legs and stimulates the blood circulation.
Sitting to Prevent Backache
Sitting puts great pressure on spinal discs. Take periodic breaks from prolonged sitting to practise stretching and relaxation exercises. Two examples will be given later in this chapter.
Be sure that the seat on which you habitually sit to do your work is well designed. It should be fully adjustable to suit your own measurements. It should support your back and legs comfortably. It should be at a height that permits you to do your work without having to stretch your arms forwards from the shoulders. It should be adequately padded yet firm. You might consider using a desk or other work surface that slopes towards you, so that you don't have to bend your head and neck down.
Do arrange things on your desk so as to avoid having to twist back and forth.
Don't cradle the telephone between your ear and shoulder. It promotes upper back tension.
Do rest your arms on armrests when they're available.
Do consider using a lumbar roll (back log), which is a support specially designed for the low back. Use it to good advantage when reading, writing, watching television or driving your car to counteract any tendency to slouch. An ordinary cushion is not to be relied upon for long-term use; only in an emergency.
Excerpted from the yoga back book by Stella Weller. Copyright © 2013 Stella Weller. Excerpted by permission of Red Wheel/Weiser, LLC.
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