Relationship between estrogen use and musculoskeletal function in postmenopausal women

Population-specific equations of age-related maximum handgrip force: a comprehensive review

Background

The measurement of handgrip force responses is important in many aspects, for example: to complement neurological assessments, to investigate the contribution of muscle mass in predicting functional outcomes, in setting realistic treatment goals, evaluating rehabilitation strategies. Normative data about handgrip force can assist the therapist in interpreting a patient's results compared with healthy individuals of the same age and gender and can serve as key decision criteria. In this context, establishing normative values of handgrip strength is crucial. Hence, the aim of the this study is to develop a tool that could be used both in rehabilitation and in the prevention of work-related musculoskeletal disorders. This tool takes the form of population-specific predictive equations, which express maximum handgrip force as a function of age.

Methodology

In order to collect data from studies measuring maximum handgrip force, three databases were searched. The search yielded 5,058 articles. Upon the removal of duplicates, the screening of abstracts and the full-text review of potentially relevant articles, 143 publications which focussed on experimental studies on various age groups were considered as fulfilling the eligibility criteria. A comprehensive literature review produced 1,276 mean values of maximum handgrip force.

Results

A meta-analysis resulted in gender- and world region-specific (general population, USA, Europe and Asia) equations expressing maximum force as a function of age. The equations showed quantitative differences and trends in maximum handgrip force among age, gender and national groups. They also showed that values of maximum handgrip force are about 40% higher for males than for females and that age-induced decrease in force differs between males and females, with a proved 35% difference between the ages of 35 and 75. The difference was lowest for the 60-64 year olds and highest for the 18-25 year-olds. The equations also showed that differences due to region are smaller than those due to age or gender.

Conclusions

The equations that were developed for this study can be beneficial in setting population-specific thresholds for rehabilitation programmes and workstation exposure. They can also contribute to the modification of commonly used methods for assessing musculoskeletal load and work-related risk of developing musculoskeletal disorders by scaling their limit values.

Reproductive factors and their association with physical and comprehensive frailty in middle-aged and older women: a large-scale population-based study

STUDY QUESTION

Are women's reproductive factors associated with physical frailty and comprehensive frailty in middle-age and later life?

SUMMARY ANSWER

Early menarche at <13 years, age at menopause <45 years, surgical menopause, experiencing miscarriage and a shorter reproductive period of <35 years were associated with increased odds of frailty, while having two or three children was related to decreased likelihood of frailty.

WHAT IS KNOWN ALREADY

Evidence has shown that women are frailer than men in all age groups and across different populations, although women have longer lifespans. Female-specific reproductive factors may be related to risk of frailty in women.

STUDY DESIGN SIZE DURATION

A population-based cross-sectional study involved 189 898 women from the UK Biobank.

PARTICIPANTS/MATERIALS SETTING METHODS

Frailty phenotype and frailty index were used to assess physical frailty and comprehensive frailty (assessed using 38 health indicators for physical and mental wellbeing), respectively. Multivariable logistic regression models were used to estimate odds ratios (ORs) and 95% CI between reproductive factors and likelihood of physical frailty and comprehensive frailty. Restricted cubic spline models were used to test the non-linear associations between them. In addition, we examined the combined effect of categorized age at menopause and menopause hormone therapy (MHT) on frailty.

MAIN RESULTS AND THE ROLE OF CHANCE

There was a J-shape relationship between age at menarche, reproductive period, and frailty; age at menarche <13 years and >16 years, and reproductive period <35 years or >40 years were all associated with increased odds of frailty. There was a negative linear relationship between menopausal age (either natural or surgical) and odds of frailty. Surgical menopause was associated with 30% higher odds of physical frailty (1.34, 1.27-1.43) and 30% higher odds of comprehensive frailty (1.30, 1.25-1.35). Having two or three children was linked to the lowest likelihood of physical frailty (0.48, 0.38-0.59) and comprehensive frailty (0.72, 0.64-0.81). Experiencing a miscarriage increased the odds of frailty. MHT use was linked to increased odds of physical frailty in women with normal age at natural menopause (after 45 years), while no elevated likelihood was observed in women with early natural menopause taking MHT.

LIMITATIONS REASONS FOR CAUTION

The reproductive factors were self-reported and the data might be subject to recall bias. We lacked information on the types and initiation time of MHT, could not identify infertile women who later became pregnant, and the number of infertile women may be underestimated. Individuals participating in the UK Biobank are not representative of the general UK population, limiting the generalization of our findings.

WIDER IMPLICATION OF THE FINDINGS

The reproductive factors experienced by women throughout their life course can potentially predict frailty in middle and old age. Identifying these reproductive factors as potential predictors of frailty can inform healthcare providers and policymakers about the importance of considering a woman's reproductive history when assessing their risk for frailty.

STUDY FUNDING/COMPETING INTERESTS

This work was supported by the National Key Research and Development Program of China (2022YFC2703800), National Natural Science Foundation of China (82273702), Science Fund Program for Excellent Young Scholars of Shandong Province (Overseas) (2022HWYQ-030), Taishan Scholars Project Special Fund (No. tsqnz20221103), and the Qilu Young Scholar (Tier-1) Program (202099000066). All authors have no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

N/A.

The association between hormone therapy and sarcopenia in postmenopausal women: the Korea National Health and Nutrition Examination Survey, 2008-2011

Objective:

Menopausal transition contributes to sarcopenia, but the effects of hormone therapy (HT) on sarcopenia in postmenopausal women have not been determined. This study assessed the effect of HT on sarcopenia in postmenopausal women.

Methods:

The present study included 4,254 postmenopausal women who participated in the Korea National Health and Nutritional Examination Surveys from 2008 to 2011. Appendicular skeletal muscle mass divided by weight (ASM/Wt) and the prevalence of sarcopenia were analyzed in groups of women stratified by duration of HT use.

Results:

ASM/Wt was higher and the prevalence of sarcopenia was lower in participants with a history of prolonged (≥13 mo) HT use than in participants with a shorter duration of HT use or no HT use. After adjusting for multiple confounding factors, prolonged use of HT remained significantly associated with estimated mean ASM/Wt and the prevalence of sarcopenia (odds ratio: 0.60; 95% confidence interval: 0.41-0.88; P = 0.01). In addition, the prevalence of sarcopenia was linearly associated with history of hypertension, duration of hypertension, physical activity, and duration of HT use. Subgroup analysis showed that the association between duration of HT use and the prevalence of sarcopenia was maintained in younger (<65 y old) and leaner (body mass index <25 kg/m²) postmenopausal women.

Conclusions:

The present study showed that the prolonged use of HT was associated with high muscle mass and a low prevalence of sarcopenia in postmenopausal women.

Body Composition Analysis of 10 Years versus 5 Years of Adjuvant Endocrine Therapy in Patients with Nonmetastatic Breast Cancer

OBJECTIVE

Our study aims to investigate the association of extended adjuvant endocrine therapy with disease-free survival (DFS), muscle mass, muscle strength, and visceral adipose tissue in patients with nonmetastatic breast cancer and the effect of extended endocrine therapy on body composition. Patients and Methods. Patients (N = 90) with nonmetastatic breast cancer aged between 60 and 65 years old were prospectively recruited in this study, compromising a cohort of subjects rece iving 5 years or 10 years of adjuvant endocrine therapy. Patients' DFS was compared between these two groups. Patients' body composition including muscle and fat using CT scans, muscle strength, and gait speed was evaluated in these two groups.

RESULTS

Dietary behavior was recorded with the food frequency questionnaire (FFQ). Patients' age, body weight, and body mass index (BMI) did not differ between the two groups. An extended adjuvant endocrine therapy into 10 years could translate into DFS benefit (123.8 vs. 102.2 months, P=0.038). Patients receiving 10 years of adjuvant endocrine therapy had less skeletal muscle and more visceral fat compared with patients receiving 5 years of adjuvant endocrine therapy. The skeletal muscle index was 50.3 ± 1.6 cm2/m2 versus 46.5 ± 1.3 cm2/m2 in the 10 years or 5 years of adjuvant endocrine therapy group (P=0.042). The visceral fat was 28.9 ± 2.9 cm2/m2 versus 55.0 ± 3.2 cm2/m2 in the 10 years or 5 years of adjuvant endocrine therapy group (P=0.011). The muscle strength, gait speed, and FFQ results in the two groups not reaching statistical difference.

CONCLUSION

In conclusion, breast cancer patients with 10 years of adjuvant endocrine therapy had DFS benefit, but with more muscle loss and adipose tissue deposits compared to patients receiving 5 years of adjuvant endocrine therapy.

Association Between Hormone Therapy and Muscle Mass in Postmenopausal Women: A Systematic Review and Meta-analysis

IMPORTANCE

Hormone therapy (HT) has been suggested for protection against age-related muscle weakness in women. However, the potential for HT-associated health risks necessitates a better understanding of the direction and magnitude of the association between HT and health outcomes, such as lean body mass (LBM).

OBJECTIVE

To determine whether HT was associated with reduced LBM loss compared with not receiving HT among postmenopausal women aged 50 years and older.

DATA SOURCES

MEDLINE, Embase, AgeLine, CINAHL, and SportDiscus (searched from inception until April 25, 2018).

STUDY SELECTION

For this systematic review and meta-analysis, randomized clinical trials including postmenopausal women undergoing HT and control groups of women not receiving HT were selected by 2 reviewers. Studies were included if LBM or fat-free mass were measured as an outcome. Studies with participants from hospitals, long-term care facilities, or with specific diseases were excluded.

DATA EXTRACTION AND SYNTHESIS

Information regarding study characteristics and outcome measures were extracted by 1 reviewer and verified by another. Risk of bias was evaluated. Quality of evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines were used to abstract data and assess data quality/validity. Data were pooled using a fixed-effects model.

MAIN OUTCOMES AND MEASURES

The primary study outcome was the overall absolute change in LBM (measured in kilograms), captured by dual-energy x-ray absorptiometry, dual-photon absorptiometry, or bioelectrical impedance analysis imaging.

RESULTS

Of 8961 studies that met selection criteria, 12 were included, with a total of 4474 recruited participants. Of the participants, mean (SD) age was 59.0 (6.1) years. Data on ethnicity were collected by 2 of the studies. Of the 22 HT intervention arms, 15 used estrogen-progesterone combination HT and 7 used estrogen-only HT. Control participants were women who received no HT at all or who received placebo. The median follow-up duration was 2 years (range, 6 months to 6 years). Seven treatment arms showed a loss of LBM, and 14 were protective. Overall, HT users lost 0.06 kg (95% CI, -0.05 to 0.18) less LBM compared with control participants, but the difference was not statistically significant (P = .26). The results were unchanged when stratified based on treatment type and dosage, duration of follow-up, time since menopause, study quality, and type of LBM measurement, with HT users losing between 0.06 kg more to 0.20 kg less LBM compared with control participants for all strata. The quality of evidence based on GRADE was low.

CONCLUSIONS AND RELEVANCE

This systematic review and meta-analysis did not show a significant beneficial or detrimental association of HT with muscle mass. Although muscle retention in aging women is of crucial importance, these findings suggest that interventions other than HT should be explored.

Vibration Therapy to Prevent Bone Loss and Falls: Mechanisms and Efficacy

A considerable volume of evidence has accumulated to suggest that whole-body vibration (WBV) may have a therapeutic role to play in the prevention of osteoporotic fracture, particularly for individuals who are unable to tolerate vigorous exercise interventions. There is moderate to strong evidence that WBV will prevent falls (likely due to enhanced neuromuscular function), but also some indication that the effects of WBV do not outstrip those of targeted exercise. Animal data indicates that WBV will also improve bone mass, including preventing loss due to hormone withdrawal, disuse and glucocorticoid exposure. Human trials, however, have produced equivocal outcomes for bone. Positive trends are apparent at the hip and spine, but shortcomings in study designs have limited statistical power. The mechanism of the vibration effect on bone tissue is likely to be mechanical coupling between an oscillating cell nucleus and the cytoskeleton. More robust dose-response human data are required before therapeutic guidelines can be developed.

Menopause, estrogens and frailty

The controversy surrounding the results from the Women's Health Initiative (WHI) trials published a decade ago caused a significant decline in the use of menopausal hormone replacement therapy. However, these results have been vehemently contested and several lines of evidence suggest that in perimenopausal and non-obese women, estrogen therapy may indeed be of benefit. There is ample proof that menopause causes a loss of musculoskeletal tissue mass and quality, thereby causing a loss of health and quality of life. There is also solid evidence that hormone replacement therapy in itself prevents most of these effects in connective tissue in itself. Besides the independent, direct effects on the musculoskeletal tissues, estrogen deficiency also reduces the ability to adequately respond and adapt to external mechanical and metabolic stressors, e.g. exercise, which are otherwise the main stimuli that should maintain musculoskeletal integrity and metabolic function. Thus, normophysiological estrogen levels appear to exert a permissive effect on musculoskeletal adaptations to loading, thereby likely improving the outcome of rehabilitation following critical illness, musculoskeletal trauma or orthopedic surgical therapy. These effects add to the evidence supporting the use of estrogen therapy, particularly accelerated gain of functional capacity and independence following musculoskeletal disuse.

The effect of 8 mos of twice-weekly low- or higher intensity whole body vibration on risk factors for postmenopausal hip fracture

OBJECTIVE

Whole body vibration is a potential therapy for age-related loss of musculoskeletal competence. Vibration has improved bone in animal models, but evidence in humans is limited. Relative efficacy of low- vs. high-intensity whole body vibration is also unknown. Our goal was to observe the effect of brief low- and higher intensity whole body vibration on risk factors for hip fracture in postmenopausal women.

DESIGN

We used an 8-mo randomized controlled trial design to examine the influence of twice-weekly low-intensity whole body vibration (15 mins, 30 Hz, 0.3 g) or higher intensity whole body vibration (2 × 3 mins, 12.5 Hz, 1 g) on anthropometrics, bone (whole body, hip, spine, forearm, and heel), muscle (wall squat and chair rise), and balance (tandem walk and single leg stance). Physical activity, daily calcium, and compliance were recorded. Effects were examined by repeated-measures analysis of covariance, controlling for age, height, weight, calcium, physical activity, compliance, and baseline values.

RESULTS

Forty-seven women (71.5 ± 9.0 yrs) completed the trial. There were no between-group differences in any measure at 8 mos, but within-group effects were evident. Controls lost bone at the trochanter (-6%, P = 0.03) and lumbar spine (-6.6%, P = 0.02), whereas whole body vibration groups did not. Whole body vibration subjects improved wall squat (up to 120%, P = 0.004) and chair rise performance (up to 10.5%, P = 0.05).

CONCLUSIONS

Eight mos of twice-weekly whole body vibration may reduce bone loss at the hip and spine and improve lower limb muscle function. These changes may translate to a decreased risk of falls and hip fracture.

Estradiol and genistein antagonize the ovariectomy effects on skeletal muscle myosin heavy chain expression via ER-beta mediated pathways

The age-related decline in ovarian sex hormone production following the onset of menopause alters skeletal muscle metabolic, structural and functional characteristics. The myosin heavy chain (MHC) expression pattern defines skeletal muscle contraction velocity and is therefore an important factor in skeletal muscle function. The present study was designed to examine the effects of 17beta estradiol (E2), estrogen receptor (ER) subtype selective agonists (ERalpha, ERbeta) or genistein (Gen) following ovary removal (OVX) in female Wistar rats in combination with a high intensity treadmill-based exercise protocol (Ex) or normal cage-based activity (NoEx) on MHC protein expression patterns in the slow fiber type m.Soleus (Sol) and the fast fiber type m.Gastrocnemius (Gas). Gen and E2 in the Sol significantly stimulated MHC-I expression relative to OVX only in the absence of exercise (NoEx). MHC-IIb expression in the Gas was significantly increased relative to OVX in Gen Ex and E2 Ex and NoEx groups. The estrogenic effects in the Sol and Gas were both predominantly mediated via ERbeta pathways, since the ERbeta agonist induced greater MHC increases than OVX or ERalpha. We therefore propose that high intensity exercise in combination with exposure to E2, Gen, ERalpha or ERbeta agonists in OVX rats exerts differential effects on MHC expression in skeletal muscles composed of mainly slow type I MHC (Sol) or fast type II MHC (Gas). In summary, the data shows that MHC composition is affected by estrogens and exercise in a fiber type specific manner and that these effects are mainly mediated by ER-beta. This is of great importance with respect to skeletal muscle health and potential treatment with ER selective agonists.

The influence of estrogen on skeletal muscle: sex matters

As women enter menopause, the concentration of estrogen and other female hormones declines. This hormonal decrease has been associated with a number of negative outcomes, including a greater incidence of injury as well as a delay in recovery from these injuries. Over the past two decades, our understanding of the protective effects of estrogen against various types of injury and disease states has grown immensely. In skeletal muscle, studies with animals have demonstrated that sex and estrogen may potentially influence muscle contractile properties and attenuate indices of post-exercise muscle damage, including the release of creatine kinase into the bloodstream and activity of the intramuscular lysosomal acid hydrolase, beta-glucuronidase. Furthermore, numerous studies have revealed an estrogen-mediated attenuation of infiltration of inflammatory cells such as neutrophils and macrophages into the skeletal muscles of rats following exercise or injury. Estrogen has also been shown to play a significant role in stimulating muscle repair and regenerative processes, including the activation and proliferation of satellite cells. Although the mechanisms by which estrogen exerts its influence upon indices of skeletal muscle damage, inflammation and repair have not been fully elucidated, it is thought that estrogen may potentially exert its protective effects by: (i) acting as an antioxidant, thus limiting oxidative damage; (ii) acting as a membrane stabilizer by intercalating within membrane phospholipids; and (iii) binding to estrogen receptors, thus governing the regulation of a number of downstream genes and molecular targets. In contrast to animal studies, studies with humans have not as clearly delineated an effect of estrogen on muscle contractile function or on indices of post-exercise muscle damage and inflammation. These inconsistencies have been attributed to a number of factors, including age and fitness level of subjects, the type and intensity of exercise protocols, and a focus on sex differences that typically involve factors and hormones in addition to estrogen. In recent years, hormone replacement therapy (HRT) or estrogen combined with exercise have been proposed as potentially therapeutic agents for postmenopausal women, as these agents may potentially limit muscle damage and inflammation and stimulate repair in this population. While the benefits and potential health risks of long-term HRT use have been widely debated, controlled studies using short-term HRT or other estrogen agonists may provide future new and valuable insights into understanding the effects of estrogen on skeletal muscle, and greatly benefit the aging female population. Recent studies with older females have begun to demonstrate their benefits.

Hormone therapy and skeletal muscle strength: a meta-analysis

BACKGROUND

Our objective was to perform a systematic review and meta-analysis of the research literature that compared muscle strength in postmenopausal women who were and were not on estrogen-based hormone therapy (HT).

METHODS

Twenty-three relevant studies were found. Effect sizes (ESs) were calculated as the standardized mean difference, and meta-analyses were completed using a random effects model.

RESULTS

HT was found to result in a small beneficial effect on muscle strength in postmenopausal women (overall ES = 0.23; p = .003) that equated to an approximately 5% greater strength for women on HT. Among the 23 studies, various muscle groups were assessed for strength, and those that benefitted the most were the thumb adductors (ES = 1.14; p < .001). Ten studies that compared muscle strength in rodents that were and were not estradiol deficient were also analyzed. The ES for absolute strength was moderate but not statistically significant (ES = 0.44; p = .12), whereas estradiol had a large effect on strength normalized to muscle size (ES = 0.66; p = .03).

CONCLUSION

Overall, estrogen-based treatments were found to beneficially affect strength.

Additive benefit of higher testosterone levels and vitamin D plus calcium supplementation in regard to fall risk reduction among older men and women

Higher physiologic testosterone levels among community dwelling older men and women may protect against falls, and this benefit may be further increased among those taking additional vitamin D plus calcium.

INTRODUCTION

The aim of this study is to investigate sex hormone levels and fall risk in older men and women.

METHODS

One hundred and ninety-nine men and 246 women age 65+ living at home were followed for 3 years after baseline assessment of sex hormones. Analyses controlled for several covariates, including baseline 25-hydroxyvitamin D, sex hormone binding globulin, and vitamin D plus calcium treatment (vitD+cal).

RESULTS

Compared to the lowest quartile, men and women in the highest quartile of total testosterone had a decreased odds of falling (men: OR = 0.22; 95% CI [0.07,0.72]/ women: OR = 0.34; 95% CI [0.14,0.83]); if those individuals also took vitD+cal, the fall reduction was enhanced (men: OR = 0.16; 95% CI [0.03,0.90] / women: OR = 0.15; 95% CI [0.04,0.57]). Similarly, women in the top quartile of dihydroepiandrosterone sulfate (DHEA-S) had a lower risk of falling (OR = 0.39; 95% CI [0.16,0.93]). Other sex hormones and SHBG did not predict falling in men or women.

CONCLUSIONS

Higher testosterone levels in both genders and higher DHEA-S levels in women predicted a more than 60% lower risk of falling. With vitD+cal, the anti-fall benefit of higher physiologic testosterone levels is enhanced from 78% to 84% among men and from 66% to 85% among women.

Postmenopausal HRT and tibolone in relation to muscle strength and body composition

OBJECTIVES

Sarcopenia, the loss of muscle mass with age, has a great impact on physical function, and especially in postmenopausal women, who experience a greater decline in muscle strength than do men of similar age. Conventional hormone replacement therapy (HRT) may diminish this loss of muscle strength and may even increase muscle strength. However, HRT is not currently promoted for this indication because of its negative side effects, which is why tibolone, a synthetic steroid with oestrogenic, progestogenic, and androgenic activity, may be an alternative option. The aim of this article was to review data on the effect of HRT and tibolone on muscle strength and body composition in postmenopausal women.

METHODS

Medline, Pubmed, Embase, and Sumsearch were searched for articles on the effect of HRT and tibolone on muscle strength and body composition, using the Mesh terms hormone replacement therapy and clinical trial combined with muscle strength or body composition. Tibolone was added as search term with clinical trial and muscle strength or body composition.

RESULTS

Three of five randomized controlled trials reported a significant positive effect of HRT on muscle strength but not on body composition. Tibolone significantly increased handgrip strength and isometric knee extension strength in one randomized placebo-controlled, double-blind trial and increased mean knee extensor strength in one cross-sectional study. Tibolone also increased the lean body mass and decreased the accumulation of body fat.

CONCLUSIONS

HRT and tibolone increase muscle strength. Unlike HRT, tibolone also increases lean body mass and significantly reduces the total body fat content. Further research is recommended to determine whether tibolone is a safe treatment for sarcopenia.

Patterns and Correlates of Muscle Strength Loss in Older Women

BACKGROUND

The aging process is associated with progressive declines in muscle strength, resulting in functional disability and reduced quality of life.

OBJECTIVE

The purpose of this epidemiological study was to examine the age-related loss of grip strength both cross-sectionally and longitudinally and the risk factors associated with the decline in muscle strength in a large population of community-living older women (aged 65-91 years).

METHODS

Clinical visits, including physical examinations and lifestyle assessment, were conducted at baseline and biennially afterwards for a total of 10 years of follow-up. The upper-body muscle strength was measured by grip strength using a hand-held dynamometer.

RESULTS

The muscle strength decreased cross-sectionally (n = 9,372) as well as longitudinally (n = 5,214), as age increased, and the decline in muscle strength measured during follow-up was greater than that measured cross-sectionally at baseline. The average loss of grip strength during 10 years of follow-up was 5.1 kg, equivalent to a rate of 2.4% decline per year, with the greatest loss seen in the oldest age group (80 years or older). Cross-sectional analysis revealed that the correlates of lower muscle strength included older age, greater weight, greater height loss since age 25 years, lower protein intake, difficulties in functional tasks, and lower physical activity. In longitudinal analysis, older age, baseline strength, weight and height loss during follow-up, difficulties in functional tasks, and lower physical activity were found to be significantly and independently associated with greater loss in grip strength during follow-up.

CONCLUSIONS

Cross-sectional and longitudinal analyses of age-related loss of muscle strength yielded different rates of decline. In addition to older age and difficulties in functional tasks, a number of modifiable factors, including weight and physical activity, are associated with increased decline in muscle strength among older women.

Effects of combined female sex hormone replacement therapy on body fat percentage and distribution

The effectiveness of hormone replacement therapy for patients with cardiovascular disease and for postmenopausal women with associated cardiovascular risks is currently under wide investigation. Among the cardiovascular risks are those related to body fat percentage and distribution. The present study undertook to investigate the effects of combined hormone replacement therapy on body fat percentage and distribution in postmenopausal women. Data for the present study were collected via retrospective analyses of 287 healthy postmenopausal women (146 as a study group, 141 as controls). Participants in the study group received 0.625 mg conjugated equine estrogen combined with 2.5 mg medroxyprogesterone acetate per day for 18 months. Body fat percentage and fat distribution were evaluated through the electrical impedance method and measurements of skinfold thickness, respectively. Two indices of centripetal fat distribution were defined: ratio of trunk-to-extremity skinfold thickness (T/E index), and ratio of upper-to-lower body skinfold thickness (U/L index). Investigators found that a daily dose of 0.625 mg of conjugated equine estrogen combined with 2.5 mg of medroxyprogesterone acetate taken for 18 months increased body fat percentage by decreasing lean body mass and by affecting upper-to-lower body fat distribution, without producing significant changes in overall weight. A slight decrease in the trunk-to-extremity body fat ratio was noted at 18 months of treatment, but this decrease did not reach statistical significance. Data related to the effects of hormone replacement therapy on body fat percentage and distribution in postmenopausal women are scarce. Additional research is needed to clarify the possible health benefits of hormone replacement therapy.

Estrogen replacement, muscle composition, and physical function: The Health ABC Study

PURPOSE

Although the beneficial effects of estrogen use on cardiovascular and cognitive function in postmenopausal women have been recently discredited, controversy remains regarding its usefulness for maintaining skeletal muscle mass or strength. Therefore, the purpose of this study was to determine whether estrogen use is associated with enhanced muscle composition and, if so, whether this translates into improved strength and physical function.

METHODS

Cross-sectional analysis of 840 well-functioning community-dwelling white women (current estrogen replacement therapy (ERT) users = 259, nonusers = 581) aged 70-79 yr participating in the Health, Aging and Body Composition Study. Muscle composition of the midthigh by computed tomography included cross-sectional area (CSA) of the quadriceps, hamstrings, intermuscular fat and subcutaneous fat, and muscle attenuation in Hounsfield units (HU) as a measure of muscle density. Isometric hand grip and isokinetic knee extensor strength were assessed by dynamometry. Physical function was assessed using a summary scale that included usual 6-m walk and narrow walk speed, repeated chair stands, and standing balance.

RESULTS

In analyses of covariance adjusted for relevant confounders, quadriceps muscle CSA and HU were greater in current ERT than non-ERT women (P < 0.05). Grip strength was also greater (P < 0.05) in women taking ERT while knee extensor strength approached significance (P < 0.10). However, differences in muscle composition and strength were modest at < or =3.3%. There was no difference by ERT status for the hamstring muscles, fat CSA, or for physical function.

CONCLUSION

The associations between ERT and muscle composition and strength were minor and did not translate into improved physical function. Initiation of ERT for preservation of muscle composition and function may not be indicated.

Soy isoflavones, body composition, and physical performance

OBJECTIVES

Physiologic changes, occurring during the process of aging, can have serious health consequences, such as increased risk of chronic disease and disability. Decline in estradiol levels after menopause is hypothesized to contribute to this risk. Thus, hormone therapy (HT) might prevent or delay those changes. However, HT has serious side effects and alternative approaches are needed.

METHODS

We performed a 12-month double-blind randomized trial comparing soy protein containing 99mg isoflavones (aglycone weights) with milk protein (placebo) daily in 202 postmenopausal women aged 60-75 years. Endpoints were body composition, and physical performance. Randomization resulted in reasonable well-balanced groups, 153 (76%) women completed the trial. Compliance was good (plasma genistein levels 55 +/- 101 and 1259 +/- 1610 nmol/L for placebo and soy group, respectively). The changes in the endpoints during the intervention period among the two intervention groups were analyzed.

RESULTS

Body mass index (BMI) and waist-to-hip ratio did not change during intervention. Handgrip strength at the final visit was slightly worse in the soy group compared to the placebo group (-0.45 kg (95% C.I.: -2.5, 1.6 kg; p = 0.7), but this difference was not statistically significant. Self-reported functional status, mobility and physical performance, all slightly improved during intervention but there were no differences between the groups.

CONCLUSIONS

The results of the present trial do not support the view that soy isoflavones have favorable effects on body composition and physical performance in postmenopausal women.

Removal of ovarian hormones from mature mice detrimentally affects muscle contractile function and myosin structural distribution

The purposes of this study were to determine the effects of ovarian hormone removal on force-generating capacities and contractile proteins in soleus and extensor digitorum longus (EDL) muscles of mature female mice. Six-month-old female C57BL/6 mice were randomly assigned to either an ovariectomized (OVX; n = 13) or a sham-operated (sham; n = 13) group. In vitro contractile function of soleus and EDL muscles were determined 60 days postsurgery. Total protein and contractile protein contents were quantified, and electron paramagnetic resonance (EPR) spectroscopy was used to determine myosin structural distribution during contraction. OVX mice weighed 15% more than sham mice 60 days postsurgery, and soleus and EDL muscle masses were 19 and 15% greater in OVX mice, respectively (P < or = 0.032). Soleus and EDL muscles from OVX mice generated less maximal isometric force than did those from sham mice [soleus: 0.27 (SD 0.04) vs. 0.22 N.cm.mg(-1) (SD 0.04); EDL: 0.33 (SD 0.04) vs. 0.27 N.cm.mg(-1) (SD 0.04); P < or = 0.006]. Total and contractile protein contents of soleus and EDL muscles were not different between OVX and sham mice (P > or = 0.242), indicating that the quantity of contractile machinery was not affected by removing ovarian hormones. EPR spectroscopy showed that the fraction of strong-binding myosin during contraction was 15% lower in EDL muscles from OVX mice compared with shams [0.277 (SD 0.039) vs. 0.325 (SD 0.020); P = 0.004]. These results indicate that the loss of ovarian hormones has detrimental effects on skeletal muscle force-generating capacities that can be explained by altered actin-myosin interactions.

The effect of hormone replacement therapy and/or exercise on skeletal muscle attenuation in postmenopausal women: a yearlong intervention

Hormone replacement therapy (HRT) has been reported to exert a positive effect on preserving muscle strength following the menopause, however, the mechanism of action remains unclear. We examined whether the mechanism involved preservation of muscle composition as determined by skeletal muscle attenuation. Eighty women aged 50-57 years were randomly assigned to either: HRT, exercise (Ex), HRT+exercise (ExHRT), and control (Co) for 1 year. The study was double-blinded with subjects receiving oestradiol and norethisterone acetate (Kliogest) or placebo. Exercise included progressive high-impact training for the lower limbs. Skeletal muscle attenuation in Hounsfield units (HU) was determined by computed tomography of the mid-thigh. Areas examined were the quadriceps compartment (includes intermuscular adipose tissue), quadriceps muscles, the posterior compartment and posterior muscles. Muscle performance was determined by knee extensor strength, vertical jump height, and running speed over 20 m. Fifty-one women completed the intervention. Vertical jump height and running speed improved in the HRT and ExHRT groups compared with Co (interaction, P<0.01). For both the quadriceps compartment and quadriceps muscles, HU significantly increased (interaction, P<or=0.005) for HRT, Ex, and ExHRT compared with Co. For the posterior compartment, HU for the HRT and ExHRT were significantly increased compared with Co, while for posterior muscles, ExHRT was significantly greater than Co. Although the effects were modest, the results indicate that HRT, either alone or combined with exercise, may play a role in preserving/improving skeletal muscle attenuation in early postmenopausal women and thereby exert a positive effect on muscle performance.

Postmenopausal hormone therapy and body composition--a substudy of the estrogen plus progestin trial of the Women's Health Initiative

BACKGROUND

It has been suggested that hormone therapy may help counter undesirable changes in body composition in older women.

OBJECTIVE

This study was designed to test whether estrogen plus progestin (E+P) therapy favorably affects age-related changes in body composition in postmenopausal women.

DESIGN

The substudy was composed of 835 women from the estrogen plus progestin trial of the Women's Health Initiative who were randomly assigned to receive either E+P therapy (n = 437) or placebo (n = 398). The women had a mean age of 63.1 y and, on average, were 13.8 y past menopause. More than 17% of the participants were from an ethnic minority. No significant differences in baseline body composition (measured with dual-energy X-ray absorptiometry) by intervention assignment were observed.

RESULTS

After 3 y of intervention, the women who received active E+P therapy lost less lean soft tissue mass (-0.04 kg) than did the women who received placebo (-0.44 kg; P = 0.001). Additionally, the women in the E+P group had less upper-body fat distribution than did the women in the placebo group (change in ratio of trunk to leg fat mass: -0.025 for the E+P group and 0.004 for the placebo group; P = 0.003). A sensitivity analysis, which was conducted on the women who took > or = 80% of the study medication during the intervention period, corroborated the findings from the intent-to-treat analysis.

CONCLUSIONS

A 3-y E+P intervention significantly reduced both the loss of lean soft tissue mass and the ratio of trunk to leg fat mass in postmenopausal women. However, the effect sizes were small, and whether these changes in body composition lead to significant health benefits remains to be confirmed.

The association of sex hormone levels with poor mobility, low muscle strength and incidence of falls among older men and women

OBJECTIVE

The objective of this study was to examine whether low levels of oestradiol and testosterone are associated with impaired mobility, low muscle strength and the incidence of falls in a population-based sample of older men and women.

DESIGN

Cross-sectional population-based study, based on data of the Longitudinal Ageing Study Amsterdam (LASA), including 623 men and 663 women, aged 65-88 years.

MEASUREMENTS

Serum levels of oestradiol, testosterone, albumin and sex hormone-binding globulin (SHBG) were measured. Physical performance, functional limitations and muscle strength were assessed, and a follow-up on falls was performed prospectively within 3 years.

RESULTS

After adjustment for age, level of education, alcohol use, physical activity, chronic disease and body mass index (BMI), men in the highest quartile of the oestradiol/SHBG ratio had significantly higher physical performance scores than men in the lowest quartile (beta = 0.103). Serum levels of total testosterone were positively associated with muscle strength (beta = 0.085). Calculated bioavailable testosterone levels were positively associated with physical performance and muscle strength (beta = 0.128 and 0.109 respectively). No associations of oestradiol levels with mobility were seen in women. Levels of oestradiol and testosterone were not associated with falls.

CONCLUSIONS

It can be concluded that low levels of sex hormones were associated with impaired mobility and low muscle strength in men, but not in women. Levels of sex hormones were not associated with the incidence of falls neither in men, nor in women.

A TA-repeat polymorphism in the gene for the estrogen receptor alpha does not correlate with muscle strength or body composition in young adult Swedish women

OBJECTIVES

There are conflicting data in the literature whether estrogens affect muscle strength. Prospective studies with hormone replacement therapy have not been able to convincingly demonstrate a muscular effect and the putative role of estrogen in the development of lean body mass is not established. Both lean mass and fat mass are known to be under strong genetic control and therefore we have investigated the relation between a TA-repeat in the gene for the estrogen receptor alpha (ERalpha) and muscle strength and body composition.

METHODS

175 healthy Swedish women, aged 20-39 were randomly selected from the population registry and included in the study. Body mass measurements (lean mass, fat mass, body weight and BMI) and muscle strength (quadriceps, hamstring and grip strength) were evaluated. The TA-repeat in the ERalpha gene was amplified by polymerase chain reaction.

RESULTS

Alleles with a TA-repeat length of 16 repeats or shorter were denoted short (e), and repeat length of 17 repeats or longer were denoted long (E). Women homozygous for the short and long genotype were denoted ee (31%) and EE (21%), respectively, while heterozygous individuals were denoted Ee (48%). The frequencies were in Hardy-Weinberg equilibrium. No associations were found between ERalpha genotypes and muscle strength or body composition.

CONCLUSION

The TA-repeat in the human ERalpha gene does not correlate with muscle strength or body mass measurements, indicating that body composition is not as sensitive to genetic variation in this receptor as other target organs for estrogen.

Relationship of body surface area with bone density and its risk of osteoporosis at various skeletal regions in women of mainland China

The aim of this study was to investigate the relationship between body surface area (BS) and bone mineral density (BMD) and the associated osteoporosis risk at various skeletal regions in women from mainland China. BMD was measured at the posteroanterior (PA) spine (L1-L4), supine lateral spine (L2-L4) including volumetric BMD (vBMD), hip including femoral neck, trochanter and total hip, and forearm, including radius + ulna ultradistal (R + UUD), 1/3 site (R + U1/3) and total region (R + UT) using a dual-energy X-ray absorptiometry (DXA) fan-beam bone densitometer (Hologic QDR 4500A) in 3418 females aged from 18 to 75 years. Data analysis revealed a positive correlation between BS and BMD at the various skeletal regions (r = 0.114-0.373, all P = 0.000), but no correlation with vBMD (r = 0.000, P = 0.934). Using the stepwise regression model, BMDs at various skeletal regions were dependent variables while height, weight, body mass index (BMI), BS and projective bone area (BA) were independent variables; BS was determined to be the most important variable that affected the PA spine, hip and forearm BMDs. Subjects were divided into three groups according to size: large BS group (LBSG), intermediate BS group (IBSG) and small BS group (SBSG). The BMD at different skeletal regions of subjects between groups exhibited a significant gradient difference, with LBSG > IBSG > SBSG, but this was not seen for vBMD. On the fitting curves where BMD varied with age at the PA spine, femoral neck, total hip and R + UUD, BMDs of LBSG were 6.93-9.29% higher than those of IBSG and 12.1-16.9 % higher than those of SBSG, whereas those of SBSG were 6.12-9.59% lower than those of IBSG at various skeletal regions, respectively. The prevalence rates and risks of osteoporosis of LBSG were significantly lower than those of SBSG and IBSG, whereas those of IBSG were obviously lower than those of SBSG at various skeletal regions, respectively, presenting a gradient difference among the three study groups, LBSG < IBSG < SBSG. Our study shows that the relationship between BS and BMD exceeds that between BMD and height or weight in women in mainland China. When areal BMD is employed, those with a larger BS have higher areal BMD and lower risks of osteoporosis while, conversely, those with a smaller BS have lower areal BMD, and therefore higher risk for osteoporosis. However, when vBMD is used, these differences diminish or even disappear.

Body composition and muscle performance during menopause and hormone replacement therapy

Menopausal transition is characterized by ovarian failure and its consequent decrease in female sex steroid production. Earlier studies suggest that an increase and redistribution of body fat during menopause predispose women to cardiovascular disease and metabolic syndrome. In addition, peri- and post-menopausal women seem to have less lean body mass (LBM) compared with pre-menopausal women. Accordingly, a changing ovarian hormonal status may accelerate the loss of muscle mass and result in decreased muscle performance and functional capacity. Hormone replacement therapy (HRT) has been used to treat menopausal symptoms and as a primary prevention therapy in chronic conditions. Inconsistent findings have, however, been published on the effects of HRT on body composition in post-menopausal women. Some studies clearly suggest that HRT counteracts menopause-related changes in body composition whereas others fail to show any difference between post-menopausal HRT users and abstainers. Although cross-sectional studies show conflicting results concerning the association between HRT and muscle performance, experimental trials suggest that deterioration in muscle force during menopause can be prevented by HRT. In the future, longitudinal data need to be collected to confirm changes in body composition and muscle performance during menopausal transition irrespective of age. Although HRT seems to have beneficial effects on body composition and muscle performance in healthy post-menopausal women, there is considerable variation in the effects of HRT between different studies. The underlying mechanism of HRT action on muscle performance is still unclear.

Lean body mass and bone mineral density in physically exercising postmenopausal women

OBJECTIVES

To investigate whether the relative contribution of body composition (lean and fat mass component) to postmenopausal bone mineral density (BMD) differs between women participating in physical exercise and sedentary women.

METHODS

Subjects were 45 postmenopausal women participating in regular physical exercise and 89 sedentary controls aged 50-60 years. Baseline characteristics included age, height, weight, body mass index (BMI, Wt/Ht(2)), age at menopause, and years since menopause (YSM). Body fat mass, percentage of body fat, lean body mass, and lumbar spine BMD (L2-4) were measured by dual-energy X-ray absorptiometry.

RESULTS

Although age, height, weight, BMI, and YSM did not differ between the two groups, lean body mass and lumbar spine BMD were significantly higher (P<0.05 and <0.001, respectively), while body fat mass and percentage of body fat mass were significantly lower in exercising women than in sedentary controls (P<0.05 and <0.05, respectively). In exercising women, BMD was positively correlated with lean body mass (r=0.415, P<0.01) but not with body fat mass (r=0.155, NS). Conversely, in sedentary controls, BMD was correlated with body fat mass (r=0.251, P<0.05) and lean body mass (r=0.228, P<0.05).

CONCLUSIONS

Lean body mass is a more significant determinant of postmenopausal BMD in physically exercising women than in sedentary women.