Regular moderate intensity physical activity and blood concentrations of endogenous anabolic hormones and thyroid hormones in aging men.

Background: Physical activity has been reported to affect endocrine function in elderly men.

Objective: To establish an association between regular moderate physical activity and endogenous anabolic hormone levels in healthy aging men.

Participants: Twenty four middle-aged (57.4+/-4.7 years) and 24 elderly (68.3+/-2.6 years) physically active men who in the past 10 years had been regularly bicycling during leisure time were compared with 24 middle-aged (57.9+/-4.0 years) and 24 elderly (67.2+/-1.7 years) sedentary men. Groups did not differ for body composition.

Measurements: Serum dehydroepiandrosterone sulfate (DHEAS), insulin-like growth factor-I (IGF-1), free testosterone (FT), and thyroid hormone levels were assessed.

Results: In general, elderly men had lower IGF-1 (P<0.001), DHEAS (P=0.013), and triodothyronine levels (P<0.001) than their middle-aged counterparts. Independently of age, however, physically active men had on average higher IGF-1 (P=0.031), DHEAS (P=0.001), and triodothyronine serum levels (P<0.001) than sedentary men. FT and thyroid stimulating hormone (TSH) serum concentrations did not differ across age groups, but physically active men had lower TSH values than sedentary men (P=0.021).

Conclusions: Our results suggest that, in aging men, regular moderate physical activity is associated with higher levels of IGF-1 and DHEAS levels and with thyroid function alterations.