The general population is aging at such a rate that architects, city planners, health providers, and merchants are among those taking notice. Despite the growing interest in meeting the needs of older people (variously referred to as aging, aged, geriatric, or senior citizens), there is not even agreement on the age that defines the younger boundary of this group (Machemer & Overeynder, 1993). For example, 65 years of age has often been considered the line marking off the workers from the retired, the capable from those who are becoming incapable of working and even of caring for themselves.

The widespread use of the magical age of 65 as a specific cut-off seems to have taken root in the rule that age 65 is when one is eligible to retire and draw full benefits from Social Security. It is interesting that so many assign significance to age 65 since it was apparently an arbitrarily chosen age at the time that Social Security was established. The age of eligibility for many senior citizen programs is younger, 60 years of age, while the American Association of Retired Persons, the largest organization and a very effective lobbying body for older people, requires one to have attained only 50 years of age to join (AARP, 1990). As the lower boundary moves to younger levels, some people interested in the aging process have found it necessary to distinguish the old from the very old or old-old (frail), terms that refer to people 85 years and older (Machemer & Overeynder, 1993).

For the purposes of this paper, I look at aging not as a point reached on the life-span continuum but as a process by which function begins to show a decline. I begin with a brief discussion of some of the more commonly reported areas of concern relating to mobility of all aging persons.

Osteoporosis, an absolute decrease in bone density to the point at which fractures begin to occur, is the most common age-related pathologic condition of bone (Ben-Yishay & Zuckerman, 1993). In addition to osteoporosis that results from an underlying disease process (e.g., hypothyroidism), there are two types of osteoporosis, both considered typical complications of aging. The first affects primarily vertebrae and distal radii; the second type affects primarily the hips (Ben-Yishay & Zuckerman, 1993; Smith, Gilligan, & Kwiatkowski, 1993).

Minimally, osteoporosis can result in compression of vertebrae, which in turn results in a loss of height and range of motion of the spine. Particularly in slender, Caucasian women, the loss of bone density of the spine results in spontaneous compression fractures of the thoracic and lumbar parts of the spine. The consequences may include pain, disturbance of nerve function of the lower extremities, and loss of bladder and bowel control.

A second primary target of osteoporosis is the hip, where 95% of the fractures are either of the femoral neck or intertrochanteric (Smith, Gilligan, & Kwiatkowski, 1993). Fractures of the hip are often seen as heralding the beginning of the end for older people.

A reduced ability to maintain balance is manifested in a person’s efforts to broaden his or her base of support while standing and walking. Women, for example, move from stylish pumps with heels to oxfords with broader, lower heels. Older people move more slowly and take special care with foot placement on stairs and on uneven terrain. How much of this increased caution is due to a reduction of righting and protective reflexes (Lewis & Knortz, 1993), loss of visual ability, or other factors is currently the subject of much research (Horak, Mirka, & Shupert, 1989; Winter, 1993; Woollacott, 1989).

For people in general, aging muscles remain relatively stable biochemically, and older sedentary men show only a small decrease in blood supply in com-parison with younger sedentary men. However, other typical changes of aging significantly affect muscle strength and endurance.

Aging is accompanied by a loss in the total number of muscle fibers and atrophy of those remaining. There is a reduction in the number of muscles in each motor unit and possibly in the number of motor units. As a result, a smaller amount of contractile tissue can be mobilized when a given motor unit is being recruited. Additionally, aging muscle is not able to contract as rapidly as younger muscle. Collagen fiber content increases in aging muscles, making them less compliant and, therefore, more susceptible to injury. Skeletal muscle changes in those who are aging are summarized by Menard (1993) as “a loss of endurance, strength, mass, contraction speed, and compliance.”

Connective tissues are highly dynamic structures that form the framework of many of the body’s structures, including those of ligaments and tendons. Diversity of composition allows for variations in the important properties of compliance and tensile strength. The composition varies according to function and use of structures, as well as with age. Changes associated with the aging process include increasing brittleness and vulnerability to fracture of elastic fibers, reduced shock-absorbing capacity, and reduced tissue compliance. Severely injured aging ligaments do not regain their original length, and their stress-strain properties are permanently disrupted (Menard, 1993).

As people age, their joints are typically negatively affected by several factors, including the thinning of articular cartilage, reduction of flexibility of tendons and ligaments, and reduction of vascular support (Menard, 1993). The result of years of wear on joint structures are commonly manifested in older people by pain and swelling of the knees, hips, fingers, and spine.

Compensatory measures include attempts to reduce further wear by limiting activities, strengthening muscles surrounding bothersome joints, and surgical joint replacements.

Repetitive microtrauma can result in multiple small tears in cartilage, tendons, and ligaments, and may lead to bursitis. Clinically, the person experiences debilitating pain and loss of function.

The use of canes, crutches, walkers, scooters, and wheelchairs has a negative connotation and is too often considered by a person only when it becomes absolutely necessary, frequently after a fall instead of as a preventive measure.

To accommodate for the flattening of the spinal curve, the elderly person unconsciously flexes hips and knees when standing and walking (Nasca, 1993). Consequences of these changes in relationships of body structures may include pain, decrease in balance, and reduction in strength and endurance.

Perhaps the most detrimental thing that can be done to someone who has cerebral palsy or spina bifida is done when that person is still an infant and the parent(s) are told that the condition is nonprogressive. A review of medical texts and articles on these two conditions affirms that the lesions causing the conditions are indeed nonprogressive (NIH, in press). Unfortunately, cerebral palsy and spina bifida are lifelong conditions, and although the contributing lesions may not be progressive, the conditions are now recognized as having progressive qualities. There is much variance within each condition depending upon the particular location and timing of the insult causing the abnormality.

Many resources have been expended to successfully reduce the incidence of both cerebral palsy and spina bifida. However, once the lesion has occurred, it cannot be erased. Once it is identified, the energies of professionals, caretakers, and patients are channeled into habilitation, the reduction of the effects of the lesion. Great harm can be done to a person and family by a failure to warn them that although the lesion may be nonprogressive, the condition may be progressive. Additionally, people can be seduced by the zeal of professionals into believing that if they carry out a prescribed program, all effects of the condition will disappear.

Another problem is that cerebral palsy is commonly considered to be a condition affecting only children. Recently a major lawsuit was brought to court because services were withheld from a young man of 16 years because it was thought that “people who have cerebral palsy do not need treatment after the age of 16.”

Finally, secondary disabilities have been all too easily overlooked. A secondary disability is a negative condition that develops because of the presence of a primary disability. Much attention has been given to the prevention of primary disabilities of such conditions as cerebral palsy and spina bifida, but professionals have been slow to put concerted efforts into the prevention of secondary disabilities (Pope & Tarlow, 1991).

The human body is malleable. It can be molded and shaped over time, as evidenced by people from other cultures who have necks that are a foot or more long, ear lobes that reach to their knees, or lips that protrude out from their faces like large platters. These unusual features are the result of molding from early childhood, not of genetic endowment.

People who have abnormal neuromuscular systems are prime candidates for finding that their bodies are being molded into nonfunctional shapes or positions. Persistent pulling of spastic muscles, for example, can cause the development of dislocated joints and scoliosis. Hypotonia, low muscle tone, puts one at the mercy of that strong force-gravity. Lack of or inappropriate support promotes joint dislocations, scoliosis, decrease in cardiopulmonary function, and digestive disorders. Care must be taken that the body is supported to grow in a way that promotes optimal function and comfort.

Overstretching Body Parts. The lack of sensation experienced by people who have spina bifida promotes hyperextension of joints, particularly of the lumbar spine and hips. This can lead to further loss of function, change in balance, subluxation or dislocation of the hips, and entrapment of nerves and blood vessels.

Body parts may be subjected to undue stretching when stereotypical movement patterns are allowed to be repeated over and over. Additionally, overstretching is often an unintentional part of a treatment program or functional behavior. For example, it is not unusual for a child, as a part of the treatment regimen, to be positioned in a way that promotes a certain desired motor behavior but that ignores the excessive excursion of a body part. A typical scenario might go as follows: A child is positioned prone over a wedge to promote head control. In this position the child is instructed, “Hold your head up.”

Books, pictures, or other enticements may be positioned to make holding the head up (cervical spine in extension) rewarding. Mercury switches may be used to control radios or tape players to provide immediate positive feedback. Unfortunately, when the child relaxes or muscles fatigue, the head may fall far forward. The neck is now in a position of extreme flexion, which causes overstretching of posterior neck muscles. If this, or other contraindicated movements, are allowed repeatedly over a period of time, the structures will become irrevocably overstretched. A secondary disability has now been created unnecessarily.

In the same fashion, in the name of promoting function, switch controls are sometimes placed so that a person accesses them by use of an abnormal reflex pattern. This strengthens an abnormal movement pattern while allowing body parts to move through a range so large that structures are frequently inappropriately stressed.

The Overlay of Normal Aging. People who have cerebral palsy or spina bifida traditionally spend many years perfecting motor skills that allow them mobility. Slight changes in their environment-for example, stairs with other than standard risers-can cause major problems in adjustment. It should be expected, then, that an overlay of the insidious changes brought about by the normal aging process can play havoc with a person’s ability to function. For example, there is the person who has cerebral palsy who, after years of practice, has perfected balance and ambulation. But carefully perfected balance in the body is lost when, as a natural part of the aging process, spinal curves flatten, tendons and ligaments lose flexibility, muscles lose strength, and righting and protective reflexes slow. There may be just enough change to cause falls that result in injuries such as fractures.

The effect of repetitive microtrauma that results from walking on hips where there are abnormal biomechanics must be considered. Complaints of bursitis and osteoarthritis are frequent among relatively young people with cerebral palsy.

It is not uncommon for people who have spina bifida or cerebral palsy with low muscle tone to be overweight. The extra weight adds to the stress of ambulating with crutches, so that people in their mid-twenties frequently find themselves with severely traumatized shoulder structures.

By ignoring such potential damage to body structures, are we setting people up for pain, cardiopulmonary compromise, and tissue breakdown as early as their twenties? We are seeing people who have made extraordinary efforts throughout childhood, adolescence, and early adulthood now facing unemployment, loss of their homes, and, ultimately, the loss of their independence.

Pressure from Social and Lifestyle Values. Our society values youth, physical prowess, extraordinary feats of physical ability, and normal appearance and behavior. Only when someone is particularly successful in some aspect of life does society readily accept that person’s deviation from the norm. It is the norm for people to attempt to retain or regain their youth by using creams and even surgery to reduce wrinkles, dying hair to hide dullness or gray, dieting and exercising to attain younger-looking bodies, and wearing stylishly youthful clothes.

There is a fairly narrow band of gait that is accepted as being within the norm; beyond this, we speak of abnormal gait patterns. Parents of young children who have cerebral palsy or spina bifida are encouraged by professionals (e.g., physical therapists, occupational therapists, physicians) to strive to have their children achieve a pattern of walking that is as close to normal as possible, to practice for hours on end (could this be considered developing a lifetime pattern of overuse?), and to use this ability to walk as much as possible. How can we then justify promoting the idea that someone with a spastic gait, obviously ambulating with biomechanics that are not optimal, complete a marathon run?

The same question might be asked with regard to someone with spina bifida, where the means of mobility include undue wear and tear on shoulder, elbow, and wrist joints and, frequently, repeated movements of extreme lordosis of the lumbosacral spine. Is it appropriate for distance walking to be a part of that person’s individualized education program (IEP)? And should a teenager be allowed to arrive five minutes late for each class and leave ten minutes early because of the length of time required to ambulate or operate a manual wheelchair from room to room? We must return to thinking about the reason for ambulation-to accomplish getting from one place to another.

People who have disabilities of mobility should be taught to be discriminating about their choice of mode of mobility under various circumstances. Internalizing the concepts of age-appropriate and condition-appropriate use of assistive technology should start early and be reinforced throughout life.

The Lack of Knowledge of Professionals. Although there may not be enough of them, there are people in the medical and health care professions who have specialized information and who can provide good care to persons who have cerebral palsy or spina bifida while they are young. Unfortunately, as they move out of childhood, they will find very few people who are prepared to provide them quality care (Murphy, 1993; Segalman, 1993). To compound the problem, even those people who are aging without primary disabilities find it difficult to receive quality medical care (Lewis & Knortz, 1993). The lack of knowledge about the special problems of aging leaves people to struggle on their own to find answers and guidance, a situation that certainly leads to further problems.

Interdisciplinary teams dealing with developmental disabilities must be broadened to include people who are efficiency and ergonomics experts. It should be standard practice that videotapes are taken of people in their “regular” lives. A broad array of people, including the people who have cerebral palsy or spina bifida, should analyze these, looking not only at the present physical behaviors but also considering the likely future so that the questions like “If this behavior continues for a period of years, what will be the long-term effect on the body?” and “Can the person afford that?” can be answered. This careful scrutiny can help us find alternative ways of approaching tasks and at least avoiding the effects of:

• repetitive movements when there are abnormal biomechanics;
• repeated overextension of joints from: reflex movements, spastic or athetoid (unceasing, involuntary) movements without graded co-contraction, inappropriate positions such as extreme lordotic posture, and entrapment of nerves, blood vessels, or both;
• joint dislocations (e.g., hip, temporal mandibular, shoulder);
• adopting abnormal postures for stabilization (e.g., wrapping arms around push handles and legs around uprights of wheelchairs) with consequent tearing up of joints, overstretching of structures, nerve entrapments, pain, and loss of function.