The association of bone metabolism with bone mineral density, serum sex hormone concentrations, and regular exercise in middle-aged men.

Physical activity is an important factor in attaining bone mass. Our aim was to investigate if low to moderate intensity exercise affects bone resorption [serum tartrate-resistant acid phosphatase (TRAP) 5b activity] and formation (serum osteocalcin concentration) in a randomized controlled exercise intervention trial in Finnish middle-aged men. In addition, the relations of these bone turnover markers with bone mineral density (BMD) and serum sex hormone concentrations [circulating testosterone (T), estradiol (E2), and sex hormone-binding globulin (SHBG) concentrations] were evaluated. Serum TRAP 5b activity and osteocalcin concentration were measured at randomization and after 1 and 4 years of the exercise intervention. BMDs of the lumbar spine (L2-L4), femoral neck, and total proximal femur were measured with a dual-energy X-ray absorptiometry (DXA). At randomization, TRAP 5b activity was strongly correlated with the osteocalcin concentration (Spearman r = 0.541, P < 0.0001). In addition, TRAP 5b activity was significantly correlated with proximal femur BMD values (r = -0.201, P = 0.018) and osteocalcin concentration with femoral neck and proximal femur BMD values (r = -0.187, P = 0.028; r = -0.240, P = 0.005, respectively). Serum E2, free E2, and free T concentrations were inversely correlated with both bone turnover markers. After 1 year of exercise intervention, TRAP 5b activity was significantly lower in the exercise than reference group (P = 0.006). However, after 4 years of exercise intervention, the difference was no longer statistically significant. There were no differences in the osteocalcin concentrations between the study groups during the intervention. Our results show a connection between serum TRAP 5b activity and osteocalcin concentration. Furthermore, our results suggest that low to moderate exercise intervention and serum sex hormone concentrations may induce changes in bone metabolism in middle-aged men. However, exercise-induced effects on bone metabolism should be confirmed in other randomized controlled exercise trials taking into account exercise intensity and dose-response issues.

Aerobic exercise and bone mineral density in middle-aged finnish men: a controlled randomized trial with reference to androgen receptor, aromatase, and estrogen receptor alpha gene polymorphisms.

Our aim was to investigate associations of the polymorphic loci of androgen receptor (AR), aromatase CYP19, and estrogen receptor alpha (ERalpha) genes with bone mineral density (BMD) in a four-year controlled randomized exercise intervention trial in Finnish middle-aged men. Additionally, we studied whether the gene polymorphisms affect circulating testosterone (T), estradiol (E(2)), and sex hormone-binding globulin concentrations. The polymorphic CAG repeat of the AR gene, the TTTA repeat of the human aromatase gene, and the PvuII site of the ERalpha gene were analyzed. BMDs of the lumbar spine (L2-L4), femoral neck, and total proximal femur were measured with a dual-energy X-ray absorptiometry (DXA). In the exercise group, the subjects with the ERalpha gene PP or Pp genotypes showed an increase (+6.5 and +5.1%, respectively) in lumbar spine BMDs (P = 0.007; repeated measures ANOVA) during intervention, while there was no change in the subjects with the pp genotype. The long TTTA repeat (TTTA(9-12)) in aromatase gene was associated with greater height (P = 0.026) and lower BMI (P = 0.029) values than the short TTTA repeat (TTTA(6-8)). With regard to the AR gene, no statistically significant differences in bone properties were found between the genotypes. There were no significant associations of any analyzed polymorphic sites with the serum sex steroid hormone concentrations in the exercise or reference group. In conclusion, the Finnish middle-aged men with ERalpha PP or Pp genotypes appear to have increased BMD values in the lumbar spine. This increase may reflect a predisposition to age-related degenerative changes in the spine. In addition, the AR CAG repeat and aromatase TTTA repeat do not modify the effect of regular aerobic exercise on BMD.