ReviewMenopause and sarcopenia: A potential role for sex hormones
Introduction
It is well known that menopause is characterized by important changes in hormonal status and that these changes have an important effect on bone mass density and body fat distribution [1]. In addition, a good body of evidence supports the hypothesis that the decline in estrogen levels with menopause may play a role in muscle mass loss in postmenopausal women [2]. The term that is widely used to describe the normal age-related loss in muscle mass is sarcopenia. Functional impairment and physical disability are the major consequences of sarcopenia and are associated with increased healthcare expenditures [3]. Indeed, it is estimated that the consequences of sarcopenia are responsible for approximately $18 billion in direct healthcare costs in the US annually [4]. Considering that the number of older adults is expected to double over the next 25 years, sarcopenia has become an important clinical research topic. Therefore, investigating the mechanisms underlying this condition and developing efficient interventions for the prevention and treatment of sarcopenia may be of great interest for health care professionals. In this review, we will (1) summarize the hormonal changes associated with menopause; (2) examine the role of sex hormones with regards to sarcopenia; (3) discuss the physical and metabolic consequences of sarcopenia and (4) address the potential effect of hormone replacement therapy and phytoestrogens supplementation combined or not with exercise training on muscle mass.
Section snippets
Menopause
Menopause is defined as the permanent cessation of menstruation resulting from the loss of ovarian follicular activity and marks the end of natural female reproductive life. Menopause is preceded by a period of menstrual cycle irregularity, known as the menopause transition or peri-menopause, which usually begins in the mid-40s. The menopause transition is characterized by many hormonal changes predominantly caused by a marked decline in the ovarian follicle numbers [5]. A significant decrease
Definition of sarcopenia
Sarcopenia refers to the loss of muscle mass associated with normal aging [8]. However, over the past decade, sarcopenia has often been defined as the age-related loss in muscle mass and muscle strength, which implies that these are causally linked and that changes in muscle mass are directly and fully responsible for changes in muscle strength. However, this concept has been challenged since it has been shown that age-associated changes in muscle mass explained less than 5% of the variance in
Changes in muscle morphology with sarcopenia
All skeletal muscles are composed of motor units and each motor unit contains a motor neuron and muscle fibers. Motor units can be differentiated in two main types based on the fiber type present in the motor unit. Slow motor units are mainly composed of type I fibers while fast motor units predominantly consist of type II fibers [15]. The decrease in muscle mass with aging results from loss of both slow and fast motor units, with an accelerated loss of fast motor units [16]. Moreover, there
Epidemiology of sarcopenia
The prevalence of sarcopenia highly depends on the criteria used to identify sarcopenic individuals. To our knowledge, only one study investigated the prevalence of sarcopenia in a representative sample of men and women aged 18–80 years old [12]. Indeed, Janssen al. [12] observed that the prevalence of class I and class II sarcopenia increased from the third to sixth decade and remained relatively constant thereafter. In addition, it was reported that the prevalence of class I and class II
Role of menopause associated with hormonal changes
It has been hypothesized that menopause transition and the subsequent decline in estrogen may play a role in muscle mass loss [23], [24], [25], [26]. That is, van Geel et al. [27] reported a positive relationship between lean body mass and estrogen levels. Similarly, Iannuzzi-Sucich et al. [28] observed that muscle mass is correlated significantly with plasma estrone and estradiol levels in women. However, Baumgartner et al. [29] reported that estrogen levels were not associated with muscle
Hormone replacement therapy (HRT) and phytoestrogens for improving muscle mass
Estrogen supplementation or HRT is considered as a potential strategy to play a protective role on muscle mass and muscle strength although contradictory results have been reported. For example, Sorensen et al. [42] performed a 12-week double-blind study where estrogen or placebo was administered and observed a significant increase in lean body mass. Moreover, in the Women's Health Initiative study, subjects who were randomized to receive HRT for 3 years lost 0.04 kg of lean body mass, which was
Consequences of sarcopenia
Several studies have shown an association between the loss in muscle mass and adverse clinical outcomes such as mobility limitations and fractures. That is, Janssen et al. [12] used the data of the Third National Health and Nutrition Examination Survey to investigate if sarcopenia was related to functional impairment and physical disability. Functional impairment was defined as having limitations in mobility performance such as walking and climbing stairs while physical disability refers to
Conclusion
The decrease in estrogens levels with menopause may play a potential role in the decline in muscle mass after the 5th decade of life. Sarcopenia is a complex condition involving hormonal, biological, nutritional and physical activity mechanisms. It is however difficult to establish the relative contribution of sex hormones on the onset of sarcopenia. Prospective observational studies with regular measurement of sex hormones and body composition during menopause transition, taking into account
Competing interests
This manuscript was supported by CIHR (Canadian Institute for Health Research) grants: 63279 MONET study (Montreal Ottawa New Emerging Team) and 88590 SOMET study (Sherbrooke Montreal Ottawa Emerging Team). Dr Rémi Rabasa-Lhoret and Dr Antony D. Karelis are supported by the Fonds de la recherche en santé du Québec (FRSQ). Finally, Dr Rémi Rabasa-Lhoret is the recipient of the J-A De Sève Research Chair for Clinical Research. The authors declare no conflict of interest.
Contributors
Virginie Messier: drafting; Rémi Rabasa-Lhoret: revision; Sébastien Barbat-Artigas: revision; Belinda Elisha: revision; Antony D. Karelis: revision; Mylène Aubertin-Leheudre: revision.
Provenance and peer review
Commissioned and externally peer reviewed.
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