Study of the Relation between Body Composition and Physical Performance among Elderly

Abstract

Background Body composition consists of fat and fat free mass muscle, bone, water and organs in the body 1. With advancing age, changes in body composition take place in the form of decline in skeletal muscle mass and increase in body fat with redistribution on fat in the body 2. Many physiological and pathological changes are responsible for these changes and the degree of these changes vary greatly among elderly population 3 Neuronal loss with age results in decrease in number of motor neurons with age and chronic denervation of muscle tissue with loss of muscle fibers and muscle mass. 4 Age related hormonal changes in the form of decrease in Growth Hormone, insulin like growth factor 1 and testosterone, increase in cortisol level and insulin resistance results in increase in body adiposity specially visceral fat, decrease in lean mass and bone mineral density 5 Also some inflammatory cytokines were observed to be increased in older adults such as tumor necrosis factor alpha, interleukin-6 , interleukin-1 and C-reactive protein. All of them induce inflammatory process which negatively affect muscle mass and strength. 6 Different methods used to assess body composition in elderly. Anthropometric measures such as Body mass index, waist circumference, waist hip ratio and skin fold thickness are all easy, inexpensive and portable measurements to evaluate body composition. Although they depend on skills of operator and their accuracy may vary between populations. 7 8 Dual Energy X-ray Absorpiometry DEXA , Computed Tomography CT and Magnetic Resonance Imaging MRI are all accurate validated methods to assess body composition. But all of them are expensive and nonportable methods using radiation and cannot be used in large population based studies. 9 10 11 Bioelecterical impedence analysis is a safe, portable, inexpensive and easy to use alternative that is suitable for evaluating large number of people. Results from