4. Body composition changes in old age

fractures, frailty, reduction in the quality of life and loss of independence [45]. These changes in musculoskeletal system reflect the ageing process as well as consequences of a reduced physical activity. The muscle wasting in frail older persons is termed 'sarcopaenia'. This disorder leads to a higher incidence of falls and fractures and a functional decline. Functional sarcopaenia or agerelated musculoskeletal changes affect 7% of elderly above the age of 70 years, and the rate of deterioration increases with time, affecting over 20% of the elderly by the age of 80 [46]. Strength declines at 1.5% per year, and this accelerates to as much as 3% per year after 60 years of age [47]. These rates were considered high in sedentary individuals and twice as high in men as compared with those in women [48]. However, studies show that on an average, men have larger amounts of muscle mass and a shorter survival than women. This makes sarcopaenia potentially a greater

Skeletal muscle strength (force-generating capacity) also gets reduced with ageing [45, 46] depending upon genetic, dietary and, environmental factors as well as lifestyle choices. This reduction in muscle strength causes problems in physical mobility and activity of daily living. The total amount of muscle fibres is decreased due to a depressed productive capacity of cells to produce protein. There is a decrease in the size of muscle cells, fibres and tissues along with the total loss of muscle power, muscle bulk and muscle strength of all major muscle groups like deltoids, biceps, triceps, hamstrings, gastrocnemius (calf muscle), and so on. Wear and tear or wasting of the protective cartilage of joints occurs. The cartilage normally acts as a shock absorber and a gliding agent that prevents the friction injuries of the bone. There are stiffening and fibrosis of connective tissue elements that reduce the range of motion and affect the movements by making them less efficient. As part of the normal cell division process, telomere shortening occurs. DNA is more exposed to chemicals, toxins and waste products produced in

With ageing, toxins and chemicals build up within the body and tissues. As a whole, this damages the integrity of muscle cells. Physical activity also decreases with age, due to a change in lifestyle. Somehow, the physiological changes of the muscles are aggravated by age-related neurological changes [49]. Most of the muscular activities become less efficient and less responsive with ageing as a result of a decrease in the nervous activity and nerve conduction. A study was done by Williams et al. [50], who evaluated the muscle samples from both elderly and young adults and suggested that limb muscles are 25–35% shorter and less responsive in elderly healthy individuals when compared to young adults. In addition, the overall fat content of muscles was also higher in elderly population, suggesting transformation in the normal remodelling with age. Age-related musculoskeletal changes are much more prominent in fast-twitch muscle fibres as compared to slow-twitch muscle fibres. With ageing, the total water content of the tissue decreases and loss of hydration also adds to the inelasticity and stiffness. Alterations in the basal metabolic rate and slowing metabolism (as part of the physiological ageing process) result in muscle changes. This leads to the replacement of pro-

Hormonal disorders can affect the metabolism of bones as well as muscles. Research suggests that menopause in women marks the aggravation in the deterioration of musculoskeletal changes due to lack of oestrogen that is required for the remodelling of bones and soft tissues. Certain systemic conditions like vascular disorders or metabolic disorders, in the case of

public health concern among women than among men [48].

8 Gerontology

the body. This whole process increases the vulnerability of cells.

teins with fatty tissue (that makes muscle less efficient).

The human body is made up of fat, lean tissue (muscles and organs), bones and water. After the age of 40, people start losing their lean tissue. Body organs like liver, kidneys and other organs start losing some of their cells. This decline in muscle mass is associated with weakness, disability and morbidity [57, 58].

The tendency to become shorter occurs among the different gender groups and in all races. Height loss is associated with ageing changes in the bones, muscles and joints. Studies show that people typically lose almost one-half inch (about 1 cm) every 10 years after age 40 [59]. Height loss is even more rapid after age 70. These changes can be prevented by following a healthy diet, staying physically active and preventing and treating bone loss [60, 61].

Changes in the total body weight vary for men and woman, as men often gain weight until about age 55 and then begin to lose weight later in life. This may be related to a drop in the male sex hormone testosterone. Women usually gain weight until age 67–69 and then begin to lose weight. Weight loss later in life occurs partly because fat replaces lean muscle tissue and fat weighs less than muscle [60]. Studies have also shown that older people may have almost one-third more fat compared to when they were younger. Fat tissue builds up towards the centre of the body, including around the internal organs [60, 62, 63].
