The main objectives of this competing continuation application are to develop methods of estimating the prevalence and incidence rates of sarcopenia, or deficient relative muscle mass, and to determine sex and ethnic differences in risk factors and consequences of sarcopenia in community-dwelling elderly. It is accepted that muscle mass and strength are gradually lost with age. Because there are few methods of quantifying muscle mass in population studies, and criteria for defining "deficient" muscle mass remain to be established, estimates of the prevalence and incidence of sarcopenia are lacking and the extent of the public health problem posed is unknown. Age-related loss of muscle mass is undoubtedly multifactorial. Although a variety of possible mechanisms and etiological factors have been indicated, there are few data for multivariate associations of risk factors with sarcopenia. Sarcopenia is believed to be a major factor associated with physical functional impairment, and a number of studies have reported that indicators of muscle strength and function (e.g., balance, gait speed, etc.) are associated with disability and falls in elderly people. There are few reports, however, for direct associations between sarcopenia and disability or falls. Sex and ethnic differences in rates of loss for muscles mass and strength, risk factors and consequences remain to be established. The proposed study will establish methods for defining sarcopenia using cross-sectional data collected previously in the New Mexico Elder Health Survey (NMEHS, 1993-1996, n = 883) and reference data to be collected for a population-based sample of 300 young adults 20 to 40 years of age. Risk factors and long-term consequences of sarcopenia will be studied using 4 to 10 years of follow up data by continuation of the New Mexico Aging Process Study (NMAPS, current n = 404). The following variables have been measured in the NMAPS since 1993: muscle mass from dual-energy X-ray absorptiometry, serum nutrient and hormone levels (e.g. free-T, estrone, IGF1, DHEAs, leptin), dietary intake, physical activity and resting energy expenditure, cognitive and physical functional status, disability, incident falls and morbidity. Data collected for these variables will be extended another 5 years. The NMEHS included Hispanic elderly men and women: 200 new Hispanic participants will be recruited in the NMAPS to further facilitate ethnic comparisons for risk factors and consequences of sarcopenia.