Purpose: Given that physical activity is the most important environmental moderating factor, it has been known as an effective, available, low-cost and non-pharmacological approach to increase or maintain bone density at different ages. The purpose of this study was to investigate the effect of 12 weeks of training in water, on land and combined environment on bone mineral density in premenopausal women. Methods: In this quasi-experimental study with a pretest-posttest design and a control group, 40 premenopausal women aged between 40 and 45 years were divided into four groups (with 10 patients each) based on the exercise environment: water, land, combined, and controlled. Each group exercised three days a week for 12 weeks, with each session lasting 70 minutes. The lumbar vertebrae bone mineral density of the participants was measured by DEXA before and after 12 weeks and the data were analyzed using descriptive statistics, ANOVA, Analysis of covariance and LSD, with the significance level of .For statistical calculations, SPSS software version 21 was used. Results: In the combined environment group, the lumbar vertebrae bone mineral density showed a significant increase (P>0.05), while in the control group first vertebra bone density loss was observed for the second and fourth lumbar vertebrae(P<0.05). In comparison with the control group, there was a significant difference among the first and fourth lumbar vertebrae bone mineral density in the water exercise group;first, third and fourth lumbar vertebrae density in the land exercise group; and all lumbar vertebrae density in the combined environment group. Conclusion: Given that there was no difference observed between water and land exercise groups,exercise in any environment is recommended for premenopausal women because the least effect that exercise can have is prevention of bone loss in these ages.
