In 11 older men, subcutaneous GHRH nightly for 6 weeks produced a small increase in muscle strength and reduced the need for anaerobic metabolism during stressful exercise. In a study of GH and sex steroid administraton for 6 months, baseline data from 41 healthy women and men >65y suggest that: (1) Serum IGF-I does not predict integrated GH secretion; (2) GH secretion is unrelated to lean body mass or strength, but inversely correlated with total body fat and abdominal fat mass; (3) abdominal fat is a predictor of triglyceride and HDL cholesterol, whereas total and LDL cholesterol are more closely related to GH secretion; (4) There are no effects of basal GH or IGF-I, on VO2 max. Thus, age-related reductions in GH alter cardiometabolic risk factors both directly and via effects on abdominal fat. A study of 2800 banked sera from 443 BLSA men aged 25-92 y at entry shows both cross-sectional and longitudinal decreases in testosterone (T) and free T with aging with a constant rate of change after age 30, and independent effects of smoking on sex hormone binding globulin and free T index.
