AGING, PHYSICAL-ACTIVITY, INSULIN-LIKE-GROWTH-FACTOR-I, AND BODY-COMPOSITION IN GUATEMALAN WOMEN

Aging is associated with diminished secretion of growth hormone and th e major endogenous mediator of growth hormone action, insulin-like gro wth factor I(IGF-I). Aging is also associated with decreased physical activity. Alterations in body composition characteristic of the aging process (increased fat mass and decreased lean body mass) may be relat ed to the decline in anabolic effects of IGF-I with aging, decreased p hysical activity, or both. Guatemalan women often maintain a high leve l of physical activity during aging. The purpose of this study was to determine whether IGF-I concentrations correlated with physical activi ty level (determined by standardized scoring of a self-report question naire) and body composition (determined by bioelectrical impedance ana lysis) in elderly Guatemalan women. In 112 women aged 20-87 y, we foun d a progressively lower serum IGF-I with age (r = -0.732). In subjects > 60 y of age, the self-reported activity level was associated with a lower percentage body fat (P < 0.001) but there was no significant re lation between physical activity level and either lean body mass or IG F-I. We conclude that there is a significant age-related decline in se rum IGF-I concentrations in Guatemalan women, similar to that observed in both men and women in the United States. An increased level of phy sical activity in the elderly Guatemalan population was associated wit h reduced body fat but did not modify the expected reduction in circul ating IGF-I concentrations that occurs with aging.