Introduction: Menopause is the natural termination of menstruation, which affects the quality, and important aspects of women life. The aim of this study was to investigate regular resistance training along with vitamins D and calcium intake in the pre-menopausal period on bone mineral density (BMD) in rats.
Methods:  In this experimental study, the rats were randomly divided into control groups, placebo, vitamin D, calcium, resistance training, vitamin D + calcium, vitamin D + resistance training, calcium + resistance training, vitamin D + calcium + resistance training. Control and placebo groups were fed with a standard diet and sesame oil, respectively. Ovariectomy was done after two months of resistance training (Ex), calcium (35 mg/kg) and vitamin D (10000 IU) administration. BMD and bone mineral content (BMC) were measured. Hematoxylin-eosin staining was performed to examine bone total diameter and osteoclast and osteocyte cell numbers. The statistical analysis was done by a one-way analysis of variance (SPSS 20).
Results: There was an increasing trend in BMD lumbar of the Ex group (P<0.001) in comparison with the control group. The amount of bone mineral in the whole body in calcium and calcium + resistance groups was higher than the control group (P <0.05). BMC total in the vitamin D, calcium + resistance training, vitamin D + resistance training and calcium + vitamin D + resistance-training groups was lower than the other groups. Osteoclast cell numbers were decreased in Ex, Vit D+Ex (P<0.05), Ca+Vit D, Ca+Ex and Ex+Vit D+Ca groups (P<0.001) compared to the control group, also, osteocyte numbers were decreased in VitD, Ca+Vit D (P<0.05), Ex, Vit D+Ex, and Ex+Vit D+Ca groups (P<0.001).
Conclusion: Regular resistance exercise, vitamin D and calcium supplements in pre-menopausal period can improve BMD and BMC and delay the process of osteoporosis in postmenopausal period.