Chemical equilibrium model comprising calcaneus bone mineral density, low-density lipoprotein cholesterol, and physical work capacity in premenopausal women

Abstract

Background: During menopause, bone density decreases, and low-density lipoprotein cholesterol (LDL-C) rapidly increases; a decrease in the estrogen level is a common factor in these phenomena. Methods: In this study, we focused on the fact that menopause is a spontaneous process, and aimed to derive the conditions that mitigate the decline in the osteo sono-assessment index (OSI), an index of bone mineral density (BMD), using a chemical equilibrium model. We attempted to establish the relationship between variables related to female hormone secretion (OSI, LDL-C) and a variable related to work capacity (physical work capacity [PWC] at 75% of maximal heart rate) by analogy, using the fact that Gibbs free energy, a thermodynamic variable related to spontaneous change, is related by three variables. Results: Consequently, if linearity is established between PWC and OSI when LDL-C is used as the standard, then the analogy of chemical equilibrium can be established between the deviation values of these three variables, with equilibrium constant K. Finally, the theoretically determined equilibrium model with constant K was applied to data obtained from the Sports Program Service (SPS) of the Yokohama Sports Medical Center. Conclusions: The present study suggests that the decrease in bone density could be alleviated by promoting an increase in LDL-C or by mitigating the decrease in PWC. In discussing personal health, mitigating bone density loss and maintaining a high work capacity are important components, which should also take into account the appropriate levels of LDL-C.