Effects of 17β-estradiol replacement and treadmill exercise on vertebral and femoral bones of the ovariectomized rat

To evaluate the effect of 17β-estradiol replacement (10 μg, twice a week) (E₂) and treadmill exercise (18 m/min, 45 min/day) (EX) on long bone and vertebral bone mass and density, 10-month-old rats were ovariectomized (OV) and divided into four groups: OV, OV + E₂, OV + EX, OV + EX + E₂ 2 months after surgery. After 7 weeks intervention, the calcium content and the density of lumbar-5 were higher in both OV + E₂ and OV + EX + E₂ groups than in the OV group, but, only the OV + EX + E₂ group had a significantly higher femoral bone weight and density than the OV group. After 16 weeks intervention, the bone-conserving effects of E₂ and EX were significant on lumbar-5 and femoral dry weight and density. The effect of E₂ on both two sides of bones was due to the suppression of the bone turnover rate, while EX suppressed bone turnover rate primarily on the femur. We conclude that the effect of the two interventions on lumbar-5 and femoral bone mass were additive and independent.