Uncorrected Proof Zahedan J Res Med Sci. 2022 July; 24(3):e112795. Published online 2022 June 29. doi: 10.5812/zjrms-112795. Research Article The Bone Metabolic Response to a Period of High-Intensity Intermittent Exercise Along with Calcium and Vitamin D Consumption in Postmenopausal Women Homeyra Rakhshani 1 , Reza Delavar 1, * and Morteza Nikoofar 1 1 Department of Sport Sciences, Faculty of Education and Psychology, University of Sistan and Baluchestan, Zahedan, Iran * Corresponding author: Department of Sport Sciences, Faculty of Education and Psychology, University of Sistan and Baluchestan, Zahedan, Iran. Email: delavar@ped.usb.ac.ir Received 2021 January 23; Revised 2021 July 20; Accepted 2021 July 28. Abstract Background: Estrogen deficiency and increasing its reabsorption are determining factors in reducing bone density in post- menopausal women. Objectives: The purpose of this study was to investigate the response threshold of alkaline phosphatase (ALP) and parathyroid hormone (PTH) to resistance training along with Calcium and vitamin D intake in postmenopausal women. Methods: In the present study, 17 postmenopausal women (50 - 60 years old) in Zahedan were randomly selected and divided into two groups, exercise + supplement (n = 9) and control (n = 8). The exercise + supplement group received 1,500 mg of Calcium and 600 IU daily of vitamin D. Each of them performed resistance training movements in three sets with eight repetitions, with an intensity of 55% 1RM in the first week to 65% 1RM in the fourth week for three sessions/week during four weeks. Sampling was performed before the first training session and 24 hours after the last session from the first to fourth weeks. Data were analyzed with repeated- measures analysis of variance using SPSS software version 19 (P≤0.05). Results: The results showed that Calcium and vitamin D supplementation and resistance training significantly affected PTH (P = 0.004) and ALP (P = 0.02) levels. Also, it was shown that the ALP response started in the second week (P = 0.001), while the PTH response started in the third week (P = 0.001). Conclusions: According to the findings of the present study, it can be said that in postmenopausal women, the threshold for the response of ALP to resistance training and Calcium and vitamin D intake is the second week and the threshold for the response to PTH is the third week. Keywords: Resistance Training, Calcium, Vitamin D, PTH, ALP, Postmenopausal 1. Background Among the significant characteristics of aging, some changes like estrogen deficiency and an increase in its ab- sorption are the factors that demonstrate the reduction of bone density in women (1). The annual bone density reduc- tion in menopausal women is estimated at 0.6% in 60 to 69 years old women, 1.1% in 70 to 79 years older women, and 2.1% in women higher than 80 (2). Numerous factors such as genetics and environment affect bone density. Ge- netic factors cannot be changed, but correcting some vari- ables like lifestyle, physical activities, and suitable diets ef- fectively stimulates increased bone density (3). Among the studied elements practical on the metabolism and skele- tal strength, consuming Calcium and vitamin D supple- ments is suggested as a strategic procedure to avoid pre- mature bone loss in menopausal women (4). Some stud- ies have shown that Calcium existing in the body cannot be consumed. Therefore, applying procedures like doing exercise will be a suggested method to facilitate Calcium consumption (5). It seems to do exercise influences skele- tal structure in three different procedures. The first is the direct effect imposed by transferring biological signals of mechanical receptors on bones. Mechanical signals are transmitted through the osteocytic network to the epithe- lial cells of the bone. They secrete paracrine agents such as prostaglandins and insulin-like growth factor, which re- sults in the proliferation of osteoblast cells, resulting in the synthesis of bone matrix (6). The second is the direct effect of muscle mass, which influences mechanical receptors peripherally, and it is considered the last mechanism of in- direct hormone effects (7). The third one studies the effects of hormones, of which parathyroid hormone (PTH) is the most important. It is one of the hormones that play an in- Copyright © 2022, Author(s). This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/) which permits copy and redistribute the material just in noncommercial usages, provided the original work is properly cited.