## 4 Discussion  
This study analyzed the effects of an exercise program on the representative serum osteoclastin, bone ALP, and estradiol as indicators of bone formation after 6 months of complex exercise for elderly women aged 75 years or older using public health centers in order to provide a basis for its use. This study analyzed the effect of exercise performance on osteoclastin for six months in the elderly in late years. Although there was no significant difference, osteoclastin in the control group decreased by 7.7%, and osteoclastin in the exercise group increased by 18.66%. Osteocalcin differs depending on aerobic exercise and resistance exercise [34]. As a result of 16 weeks of resistance exercise in postmenopausal women, it was reported that there was no change in osteoclastin, an indicator of bone formation [35], and there was also a report [36] that postmenopausal women's exercise treatment did not change with osteoclastin. Additionally, exercise performance in postmenopausal women increases bone mineral density, but does not change serum osteoclastin levels [37]. However, according to [PERSON] et al. [38], osteoclastin increased when anaerobic exercise was performed for 1 to 2 months [39], and low-intensity and high-intensity ladders for 6 weeks in mature male rats. As a result of exercise, the serum osteoclastin concentration was significantly increased in both groups compared to the control group, but bone density was significantly increased only in the high-intensity exercise group. Therefore, it is judged that exercise performance plays a positive role in improving maximum bone mass and bone density [40]. It was reported that ALP is a representative index reflecting the activity of osteoblasts [41] and can be used as an index of bone metabolism in subjects without liver disease or metabolic disease. As a result of analyzing the effect of exercise performance on ALP for six months in the elderly in late years in this study, the control group increased by 18.92%, and the exercise group significantly increased by 69.81%. This study, together with [PERSON] et al. [42], which reported that bone-type alkaline phosphatase increased dramatically as a result of performing a bicycle ergometer with an average age of 57 years old, a report which claimed that the concentration of BALP was high [43], a report which claimed that the bone BALP increased after 12 weeks compared to pre-exercise only in the aqua aerobic exercise group [13], and the report of [PERSON] et al. [44], which claimed that growing rats after swimming exercise for 12 weeks showed bone density higher by 13%, and bone content higher by 10% and 67% higher ALP than the control group, respectively, proved that the exercise is effective for the bone density increase in the elderly in late years. However, serum osteoclastin and ALP were increased at the time of menopause due to the compensatory process by the osteogenesis inhibitory action [45; 46; 47] and osteoporosis. Figure 3: Estradiol changes. The analysis results on the pattern of the bone formation index change according to exercise treatment in postmenopausal women with prognoses are still not clear. Therefore, along with a number of reports [48; 49], which claim that the effect on bone metabolism is different depending on the type of exercise, it is also affected by the duration of exercise [47]. To use it as an analysis index of metabolism, further analysis is required, including many cases in the future. Among endocrine hormones, aging-related hormones include growth hormone, DHEA-S (dehydroepiandrosterone sulfate), and estrogen, and these hormones show a decrease in secretion with aging [49]. After menopause, estradiol (E2), which accounts for most estrogen, is not produced, and trace levels of E2 appear [50]. This study analyzed the effect of complex exercise performance on estradiol for 6 months in the elderly in late years. Although no significant difference was found, the control group decreased by 55.09%, and the exercise group decreased by 1.85%. [PERSON] et al.