RELATIONSHIP BETWEEN AGE-ASSOCIATED ENDOCRINE DEFICIENCIES AND MUSCLEFUNCTION IN ELDERLY WOMEN - A CROSS-SECTIONAL STUDY

Objective: muscle receptors and selected anabolic effects have been id entified for both insulin-like growth factor I (IGF-I) and 1,25-dihydr oxyvitamin D (1,25(OH)(2)D-3). The aim of the present study was to tes t the hypothesis that the decreasing concentrations of these endocrine factors might be involved in the decline in muscle function that char acterizes normal human ageing. Design: cross-sectional study. Study pa rticipants: a community-based sample of 245 healthy elderly women aged 70-90 years. Exclusion criteria mere diseases or medications known to affect muscle function or the somatotrophic axis. Measurements: knee extension strength was evaluated using an isokinetic dynamometer. A st andardized questionnaire was used to assess habitual physical activity . IGF-I and 1,25(OH)(2)D-3 were measured by radioimmunoassay. Vitamin D binding protein (DBP) was measured by single radial immunodiffusion and the free 1,25(OH)(2)D-3 concentration calculated as the molar rati o of total 1,25(OH)(2)D-3 to DBP. Results: the differences in isometri c and isokinetic strength over the age range were equivalent to losses of 0.9-2.4% per year. However, no relationship was found between the somatotrophic axis or vitamin D status and knee extension strength, de spite markedly decreasing concentrations of circulating IGF-I and free 1,25(OH)(2)D-3 with age. Conclusion: levels of circulating IGF-I and free 1,25(OH)(2)D-3 appear not to be involved in the loss of muscle fu nction that characterizes normal human ageing.