The world is facing an unprecedented demographic shift in the human population. The number of people aged 65 or older is projected to increase from 524 million in 2010 to nearly 1.5 billion by 2050.1,2 With this demographic shift, a corresponding increase in the prevalence of mobility limitations and other disabilities are also expected. The prevention and postponement of mobility limitations for the aging population is of major public health importance and the role of rehabilitation specialists will be tremendously emphasized.
Older adults are diverse in their functional level ranging from senior Olympians to those who are dependent in mobility and activities of daily living (ADL). The need of older individuals to stay active and prevent functional decline also varies based on the individual's functional level. However, there are universal physiologic changes which occur with aging. In addition, reduced reserve in their organ systems may predispose older adults more vulnerable to injuries and hinder their healing regardless of their functional level. In this chapter, we will discuss the key information for rehabilitation specialists to provide optimal care for the geriatric population, including physiologic changes in organ systems with aging, their relevance in common conditions including falls and mobility limitations, and specific considerations during interventions for the geriatric population.
PHYSIOLOGIC CHANGES RELATED TO AGING
Distinguishing what changes are expected with age from those attributed to disease is essential in the assessment of the older adult. In general, most physiologic functions decline at a rate of 1% per year beginning at age 30.3 Age-related physiologic changes and their clinical significance are summarized in Table 83–1.4–6 Changes in the musculoskeletal system have particular relevance to mobility decline and are elaborated further.
Table 83–1Age-Related Changes in Multiple Organs and Systems ||Download (.pdf) Table 83–1 Age-Related Changes in Multiple Organs and Systems
|Organ/System ||Age-Related Changes |
|Musculoskeletal System || |
1.5%–2% decline in muscle strength/year after age 40.
Preferential loss of type II fibers.
Decline in muscle power is more pronounced than muscle strength.
(see more details in the text)
|Neurological System || |
Depletion of neurons in brain, and loss of anterior horn cells.
Decreased nerve conduction velocities.
|Cardiovascular system || |
Cardiac output (CO) decreases after the 3rd decade at a rate of 1%/year.
Causes for ↓ in CO: ↓ in inotropic response to catecholamines, ↑in myocardial stiffness, and progressive stiffening of the aorta (↑afterload).
Decrease in aerobic capacity (↓VO2max).
|Respiratory system || |
Linear ↓ in vital capacity: Men (26 mL/year), Women (22 mL/year) after age 20. Residual volume (RV) ↑ with age.
Total lung capacity (TLC) remains constant.
RV/TLC ↑ from 20% at age 20 to 35% at age 60.
↑ in alveolar-arterial oxygen difference (A-a)O2 due to mismatch of ventilation and perfusion.
Predisposition to pneumonia due to depression of immune system function, aspiration of oropharyngeal secretions, slower ...