Hormone replacement therapy does not augment gains in muscle strength or fat-free mass in response to weight-bearing exercise

Effects of weight-bearing dance aerobics on lower limb muscle morphology, strength and functional fitness in older women

Objective

To investigate the effects of 12-week weight-bearing dance aerobics (WBDA) on muscle morphology, strength and functional fitness in older women.

Methods

This controlled study recruited 37 female participants (66.31y ± 3.83) and divided them into intervention and control groups according to willingness. The intervention group received 90-min WBDA thrice a week for 12 weeks, while the control group maintained normal activities. The groups were then compared by measuring muscle thickness, fiber length and pennation angle by ultrasound, muscle strength using an isokinetic multi-joint module and functional fitness, such as 2-min step test, 30-s chair stand, chair sit-and-reach, TUG and single-legged closed-eyed standing test. The morphology, strength, and functional fitness were compared using ANCOVA or Mann-Whitney U test to study the effects of 12 weeks WBDA.

Results

Among all recruited participants, 33 completed all tests. After 12 weeks, the thickness of the vastus intermedius (F = 17.85, P < 0.01) and quadriceps (F = 15.62, P < 0.01) was significantly increased in the intervention group compared to the control group, along with a significant increase in the torque/weight of the knee flexor muscles (F = 4.47, P = 0.04). Similarly, the intervention group revealed a significant improvement in the single-legged closed-eyed standing test (z = -2.16, P = 0.03) compared to the control group.

Conclusion

The study concluded that compared to the non-exercising control group, 12-week WBDA was shown to thicken vastus intermedius, increase muscle strength, and improve physical function in older women. In addition, this study provides a reference exercise program for older women.

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 Intricate Web of Fatigue in Women

The modern woman has taken her rightful place in society as a worker, a caregiver, a mother, and a world citizen. However, along with the privileges of these roles comes the great cost of stress and resultant exhaustion and fatigue. Psychosocial, physical, cultural, and disease-related realms of stress act as strands of a web that serve to bind and hinder women with chronic stress. New areas of research, such as exercise intervention, improved social programs (e.g., childcare), and supplementation are constantly evaluated for effectiveness alongside traditional remedies such as exercise. This review will highlight some of the key issues regarding stress in women and explore reports of new treatment modalities in light of the specific requirements of the modern woman.

Protein Requirements for Master Athletes: Just Older Versions of Their Younger Selves

It is established that protein requirements are elevated in athletes to support their training and post-exercise recovery and adaptation, especially within skeletal muscle. However, research on the requirements for this macronutrient has been performed almost exclusively in younger athletes, which may complicate their translation to the growing population of Master athletes (i.e. > 35 years old). In contrast to older (> 65 years) untrained adults who typically demonstrate anabolic resistance to dietary protein as a primary mediator of the ‘normal’ age-related loss of muscle mass and strength, Master athletes are generally considered successful models of aging as evidenced by possessing similar body composition, muscle mass, and aerobic fitness as untrained adults more than half their age. The primary physiology changes considered to underpin the anabolic resistance of aging are precipitated or exacerbated by physical inactivity, which has led to higher protein recommendations to stimulate muscle protein synthesis in older untrained compared to younger untrained adults. This review puts forth the argument that Master athletes have similar muscle characteristics, physiological responses to exercise, and protein metabolism as young athletes and, therefore, are unlikely to have protein requirements that are different from their young contemporaries. Recommendations for protein amount, type, and pattern will be discussed for Master athletes to enhance their recovery from and adaptation to resistance and endurance training.

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.

Appendicular lean mass is lower in late compared with early perimenopausal women: potential role of FSH

Age-related declines in skeletal muscle mass (i.e., sarcopenia) contribute to physical disability in older women. Although a menopause-related increase in fat mass is well documented, whether menopause influences muscle mass and sarcopenia is unclear. We determined the extent to which skeletal muscle mass differs across the stages of the menopause transition in women and whether these differences are associated with estradiol or other sex hormones. This was a cross-sectional study of 144 healthy women (aged 30-70 yr) classified as premenopausal [n = 30, 38 ± 6 yr (means ± SD)], early (n = 31, 50 ± 3 yr) and late (n = 30, 50 ± 4 yr) perimenopausal, and early (n = 26, 55 ± 3 yr) and late (n = 27, 62 ± 4 yr) postmenopausal. Appendicular lean mass (ALM) adjusted by the square of height in meters (ALM index; ALMi) was assessed by dual-energy X-ray absorptiometry. ALMi was lower (P < 0.05) in late perimenopausal and postmenopausal compared with early perimenopausal, with no significant differences between other groups (premenopausal 6.6 ± 0.6, early perimenopausal 6.8 ± 0.8, late perimenopausal 6.1 ± 0.8, early postmenopausal 6.5 ± 1.1, and late postmenopausal 6.2 ± 0.9 kg/m²). The prevalence of sarcopenia (ALMi ≤ 5.67 kg/m²) was 7%, 3%, 30%, 27%, and 32% in premenopausal, early and late perimenopausal, and early and late postmenopausal groups, respectively. ALMi measured across menopause stages was inversely correlated to follicle-stimulating hormone (FSH; r = -0.28, P = 0.003) but not to estradiol (r = 0.088, P = 0.34). The menopause transition appears to be a vulnerable period for the loss of skeletal muscle mass that may begin during the late perimenopausal transition. Future studies are necessary to investigate the potential effect of FSH on skeletal muscle.NEW & NOTEWORTHY Our data suggest that the late perimenopausal stage may be a vulnerable period for the loss of skeletal muscle, potentially related to elevations in FSH.

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.

Estrogen Effects on Skeletal Muscle Insulin-Like Growth Factor–1 and Myostatin in Ovariectomized Rats

Previous work showed that estrogen replacement attenuates muscle growth in immature rats. The present study examined muscle insulin-like growth factor–1 (IGF-1) and myostatin expression to determine whether these growth regulators might be involved in mediating estrogen’s effects on muscle growth. IGF-1 and myostatin message and protein expression in selected skeletal muscles from 7-week-old sham-ovariectomized (SHAM) and ovariectomized rats that received continuous estrogen (OVX/E2) or solvent vehicle (OVX/CO) from an implant for 1 week or 5 weeks was measured. In the 1-week study, ovariectomy increased IGF-1 mRNA expression in fast extensor digitorum longus and gastrocnemius muscles; the increase was reversed by estrogen replacement. A similar trend was observed in the slow soleus muscle, although the change was not statistically significant. In contrast to mRNA, muscle IGF-1 protein expression was not different between SHAM and OVX/ CO animals in the 1-week study. One week of estrogen replacement significantly decreased IGF-1 protein level in all muscles examined. Myostatin mRNA expression was not different among the 1-week treatment groups. One week of estrogen replacement significantly increased myostatin protein in the slow soleus muscle but not the fast extensor digitorum longus and gastrocnemius muscles. There was no treatment effect on IGF-1 and myostatin expression in the 5-week study; this finding suggested a transient estrogen effect or upregulation of a compensatory mechanism to counteract the estrogen effect observed at the earlier time point. This investigation is the first to explore ovariectomy and estrogen effects on skeletal muscle IGF-1 and myostatin expression. Results suggest that reduced levels of muscle IGF-1 protein may mediate estrogen’s effect on growth in immature, ovariectomized rats. Increased levels of muscle myostatin protein may also have a role in mediating estrogen’s effects on growth in slow but not fast skeletal muscle.

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.

CORRELATIONS BETWEEN ISOMETRIC QUADRICEPS MUSCLE STRENGTH AND BONE MINERAL DENSITY

The purpose of this study was to evaluate the relationship between isometric quadriceps muscle strength and measurements of bone density (BMD), mass (BMC) and ultrasound properties. A total of 113 individuals were included, 53 men and 60 women aged 22-85 years. Isometric quadriceps muscle strength correlated significantly to BMD of the total body for both men (r=0.63, p=0.02) and women r=0.77, p=0.04) after adjustments for age, weight and height. In women, there was also an association between isometric quadriceps muscle strength and BMD of the lumbar spine (r=0.67, p=0.04). These correlations were evident in premenopausal women for BMD at the lumbar spine, femoral neck and total body whereas no significant relationships were seen in postmenopausal women or any age group of men. For isometric quadriceps muscle strength and the ultrasound measurements of the heel, a positive correlation was seen in men and women aged 41-60 years. The findings point to a role of endogenous sex steroids, primarily estrogens, in the correlation between BMD and isometric quadriceps muscle strength.

Benefits of estrogen replacement for skeletal muscle mass and function in post-menopausal females: evidence from human and animal studies

Age related loss of skeletal muscle mass and strength accelerates with the onset of menopause in women. Recent evidence from human and animal studies provides compelling evidence for the role of estrogen based hormone replacement therapy (HRT) in maintaining and enhancing muscle mass and strength and protecting against muscle damage. The physiological mechanisms by which estrogen can positively influence skeletal muscle mass and strength and protect against post-damage inflammation and disruption are also beginning to emerge. These less well known benefits of estrogen for skeletal muscle coupled with other benefits of estrogen to bone and metabolic health in older females provide further incentives for HRT use to enhance overall health in post-menopausal women. New research also attests to the safety of shorter term HRT in younger post-menopausal females. Overall the benefits of HRT to muscle health and function could assist in offsetting age related loss of muscle mass and function and delay age related morbidity and their use for overall health benefits in aging females should continue to be evaluated.

Treatment strategies for sarcopenia and frailty

Sarcopenia is the key feature of frailty in older people and a major determinant of adverse health outcomes such as functional limitations and disability. Resistance training and adequate protein and energy intake are the key strategies for the management of sarcopenia. Management of weight loss and resistance training are the most relevant protective countermeasures to slow down the decline of muscle mass and muscle strength. The quality of amino acids in the diet is an important factor for stimulating protein synthesis. Vitamin D deficiency should be treated, and new pharmacologic approaches for sarcopenia are currently assessed.

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.

Validated treatments and therapeutic perspectives regarding physical activities

Current knowledge on physical activity in regard to sarcopenia is reported in this manuscript. The consequences of inactivity on muscle mass and function are discussed. Impact of resistance training on muscle and mass and function as well as its interaction with other factors associated with sarcopenia such as denervation, hormones modification and protein intake will be discussed.

Sarcopenia: its assessment, etiology, pathogenesis, consequences and future perspectives

Sarcopenia is a loss of muscle protein mass and loss of muscle function. It occurs with increasing age, being a major component in the development of frailty. Current knowledge on its assessment, etiology, pathogenesis, consequences and future perspectives are reported in the present review. On-going and future clinical trials on sarcopenia may radically change our preventive and therapeutic approaches of mobility disability in older people.

Skeletal muscle and bone: effect of sex steroids and aging

Both estrogen and testosterone are present in males and females. Both hormones contribute to the well being of skeletal muscle and bone in men and women, and there is evidence that the loss of sex hormones is associated with the age-related decline in bone and skeletal muscle mass. Hormonal supplementation of older adults to restore estrogen and testosterone levels to those of young men and women is not without penalty.

Effect of estrogenic compounds (estrogen or phytoestrogens) combined with exercise on bone and muscle mass in older individuals

Exercise has a beneficial effect on bone, possibly by stimulating estrogen receptor alpha. Because estrogen up-regulates this receptor, estrogen therapy combined with exercise training may be optimal for increasing bone mineral density. Studies combining estrogen therapy and exercise training in postmenopausal women show mixed results, but indicate that the combination of interventions may be more effective for increasing bone mass than either intervention alone. Plant-like estrogens (i.e phytoestrogens such as soy isoflavones) may act as weak estrogen agonists or antagonists, have small beneficial effects on bone, and may interact with exercise for increasing bone mineral density. Phytoestrogen derived from flaxseed (flax lignans) has not been evaluated as extensively as soy isoflavones and thus its effect on bone is difficult to determine. Estrogen or soy isoflavones given to postmenopausal women results in a small increase in lean tissue mass that may be mediated through estrogen receptor alpha on muscle or through decreased inflammation.

Interaction between playing golf and HRT on vertebral bone properties in post-menopausal women measured by QCT

We investigated the effect of playing regular golf and HRT on lumbar and thoracic vertebral bone parameters (measured by QCT) in 72 post-menopausal women. The main finding of this study was that there was positive interaction between golf and HRT on vertebral body CSA and BMC at the thoracic 12 and lumbar 2 vertebra but not the third and seventh thoracic vertebras.

INTRODUCTION

Identifying specific exercises that load the spine sufficiently to be osteogenic is an important component of primary osteoporosis prevention. The aim of this study was to determine if in postmenopausal women regular participation in golf resulted in greater paravertebral muscle mass and improved vertebral bone strength.

METHODS

Forty-seven postmenopausal women who played golf regularly were compared to 25 controls. Bone parameters at the mid-vertebral body were determined by QCT at spinal levels T3, T7, T12 and L2 (cross-sectional area (CSA), total volumetric BMD (vBMD), trabecular vBMD of the central 50% of total CSA, BMC and cortical rim thickness). At T7 and L2, CSA of trunk muscles was determined.

RESULTS

There was a positive interaction between golf and HRT for vertebral CSA and BMC at T12 and L2, but not at T3 or T7 (p ranging < 0.02 to 0.07). Current HRT use was associated with a 10-15% greater total and trabecular vBMD at all measured vertebral levels. Paravertebral muscle CSA did not differ between groups. Vertebral CSA was the bone parameter significantly related to muscle CSA.

CONCLUSION

These findings provide preliminary evidence that playing golf may improve lower spine bone strength in postmenopausal women who are using HRT.

The role of hormones, cytokines and heat shock proteins during age-related muscle loss

Ageing is associated with a progressive decline of muscle mass, strength, and quality, a condition known as sarcopenia. Due to the progressive ageing of western populations, age-related sarcopenia is a major public health problem. Several possible mechanisms for age-related muscle atrophy have been described; however the precise contribution of each is unknown. Age-related muscle loss is thought to be a multi-factoral process composed of events such as physical activity, nutritional intake, oxidative stress, inflammatory insults and hormonal changes. There is a need for a greater understanding of the loss of muscle mass with age as this could have a dramatic impact on the elderly and critically ill if this research leads to maintenance or improvement in functional ability. This review aims to outline the process of skeletal muscle degeneration with ageing, normal and aberrant skeletal muscle regeneration, and to address recent research on the effects of gender and sex steroid hormones during the process of age-related muscle loss.

Loss of Appendicular Muscle Mass and Loss of Muscle Strength in Young Postmenopausal Women

BACKGROUND

Different factors may predict loss of appendicular muscle mass (LossAMM) and loss of muscle strength (LossMS). We investigated the relationship between LossAMM or LossMS and baseline anthropometric measures, lifestyle habits, hormones, lipid profiles, and inflammatory markers in 49 healthy postmenopausal women (54.1 +/- 4.3 years) in a 24-36-month prospective study.

METHODS

We measured parameters of lifestyle habits, anthropometry, lipid profiles, and blood levels of testosterone, estrone, estradiol, cortisol, dihydroepiandrostenedione, luteinizing hormone, intact parathyroid hormone (iPTH), 25-hydroxyvitamin D, thyroxine, leptin, adiponectin, C-reactive protein (CRP), and interleukin-6 and interleukin-2 receptors. Percentage of loss per year of isometric knee extensor strength defined LossMS, and percentage of loss of AMM per year (dual x-ray absorptiometry) defined LossAMM.

RESULTS

The means (standard deviation) for LossMS and LossAMM were 1.17%/y (2.03) and 0.60%/y (0.74) and did not correlate (r = -0.001; p =.99). LossMS correlated negatively with level of physical activity (r = -0.28), femoral BMD (r = -0.30), alcohol consumption (r = -0.30), and luteinizing hormone (r = -0.32) and positively with estrone (r = 0.29) and iPTH (r = 0.32) (each at p <.05). LossAMM correlated negatively with AMM (r = -0.41; p <.01). Stepwise regression analyses showed that LossMS was significantly predicted by baseline physical activity (beta = -0.39) with an explanation of variation of the model (R(2)) of 6%, body mass index (BMI) (-0.40; 3%), high-density lipoprotein cholesterol (-0.29; 3%), estrone (0.32; 6%), iPTH (0.27; 7%), and interleukin-2 receptor (0.32; 5%). LossAMM was predicted by baseline height (0.56; 47%), body mass index (1.04; 83%), AMM (-0.92; 76%), thyroxine (-0.33; 8%), estrone (-0.61; 30%), and dihydroepiandrostenedione (0.44; 28%).

CONCLUSIONS

LossMS and LossAMM in young postmenopausal women were not correlated with one another, and were determined by different factors.

Oestrogen status in relation to the early training responses in human thumb adductor muscles

AIMS

The aims of this study were to identify the mechanisms for the early response to training in women of different oestrogen status and to determine whether any oestrogen and exercise effects on these would be additive.

METHODS

We monitored training (ten 5-s contractions per day for 12 weeks)-induced changes in the size, strength, voluntary activation capacity and index of crossbridge force state (i.e. rapid stretch to isometric torque ratio), in the thumb adductor muscles of postmenopausal [eight who had never used, and 14 who were using, hormone replacement therapy (HRT)] and seven premenopausal eumenorrhoeic women. The contralateral untrained muscle was used as a control.

RESULTS

There was a significant effect of oestrogen status on the magnitude of training-induced strength increment, with the non-HRT postmenopausal group exhibiting the greatest benefits (28 +/- 6%, P = 0.024) from training. There were no significant or commensurate changes in either cross-sectional area or voluntary activation capacity. The index of crossbridge force state improved most in the no-HRT group (19 +/- 7%, P < 0.05).

CONCLUSIONS

Presence, rather than absence of oestrogen, is associated with relatively higher muscle function which limits the potential for any further training-induced increments in muscle performance, as would be expected if the muscle strengthening actions of training and oestrogen share a common, partially saturable physiological pathway. The mechanism that is involved in the early training-induced strength increment in the three differing oestrogen groups cannot be due to increased size or recruitment. It would appear instead that increased motor unit firing frequency is involved.

Effects of ultra-low-dose estrogen therapy on muscle and physical function in older women

OBJECTIVES

To determine the effects of ultra-low-dose hormone therapy on muscle mass and physical function in community-dwelling women.

DESIGN

Double-blind, placebo-controlled trial.

SETTING

Clinical research center in Connecticut.

PARTICIPANTS

Healthy, community-dwelling women aged 65 and older (n=167).

INTERVENTION

Eligible women were randomly assigned to treatment with 0.25 mg 17-beta estradiol or placebo for 36 months. All women (estradiol or placebo) with an intact uterus received micronized progesterone 100 mg/d for 2 weeks every 6 months. All participants received 1,300 mg elemental calcium with 1,000 IU vitamin D per day.

MEASUREMENTS

Appendicular skeletal muscle mass (ASM), lean body mass (LBM), and percentage body fat were measured using dual x-ray absorptiometry. Sarcopenia was defined as skeletal muscle mass (ASM/height2) 2 standard deviations or less than young, healthy reference population mean. Physical activity (Physical Activity Scale in the Elderly (PASE)) and performance were measured. Serum estrone, estradiol, and sex hormone-binding globulin were measured.

RESULTS

The prevalence of sarcopenia at baseline was 13%. There were no baseline differences between groups except for PASE score and chair rise time, in which the estrogen group had better performance. No changes in ASM, LBM, percentage of body fat, or physical performance were found after 3 years of estrogen therapy.

CONCLUSION

Sarcopenia was present in 13% of this group of community-dwelling, postmenopausal older women. Ultra-low-dose estrogen therapy neither improves nor harms ASM. Similarly, no changes in body fat or physical performance were detected.

Power output, isometric strength and steadiness in the leg muscles of pre- and postmenopausal women; the effects of hormone replacement therapy

There are conflicting reports of the effects of hormone replacement therapy (HRT) on strength preservation in postmenopausal women, while any effect on power output has received little attention. Decreased steadiness of force generation has been reported in older muscles and may be related to the hormonal changes associated with the menopause, but the effect of HRT has not been investigated. We have studied the effect of HRT on strength, power output and isometric force steadiness in healthy women. Sixteen young (aged 27.4 +/- 1.4 years, mean +/- SEM) and 29 postmenopausal women were studied. Fifteen of the latter were taking HRT (68.1 +/- 1.4 years, HRT+) and 14 (70.5 +/- 1.5 years, HRT-) had never done so. During isometric quadriceps contractions the force steadiness (coefficient of variation of force) was measured at 10, 25, 50 and 100% maximum voluntary contraction (MVC). The average power generated by an explosive leg extension was recorded. The HRT- group generated less power (110.2 +/- 7.2 W) than both the HRT+ (136.5 +/- 10.9 W, P = 0.027) and young (136.2 +/- 5.8 W, P = 0.027) subjects. Power output was similar in the HRT+ and younger subjects. The HRT- subjects were weaker than the younger ones (241.3 +/- 14.0 N vs. 297.6 +/- 13 N, P = 0.006). The strength of the HRT+ group (255.5 +/- 14 N) was not significantly different to the other two groups. There was no difference in steadiness between the three groups at any of the force levels. HRT appears to maintain power output to a greater extent than isometric strength in postmenopausal women. There was no evidence for an effect of either age or HRT on isometric steadiness in the quadriceps.

Home-based resistance training improves femoral bone mineral density in women on hormone therapy

This study tested whether moderate resistance training would improve femoral bone mineral density (BMD) in long-term users of hormone therapy with low BMD. The study was a 2-year randomized, controlled, trial (RCT) of moderate resistance training of either the lower extremity or the upper extremity. Eighty-five women participated in a 6-month observation period. The setting was center-based and home-based training. The participants were 189 women aged 59-78 years, with total femur T-scores from -0.8 to -2.8 and on hormone therapy (HT) for a minimum of 2 years (mean 11.8 years); 153 completed the trial. Lower extremity training used weight belts (mean 7.8 kg) in step-ups and chair rises; upper extremity training used elastic bands and dumbbells. Measurements were BMD and body composition [dual-energy X-ray absorptiometry (DXA)], bone turnover markers. Total femoral BMD showed a downward trend during the observation period: 0.35%+/-0.18% (P=0.14). The response to training was similar in the upper and lower groups in the primary outcomes. At 2 years, total femoral BMD increased 1.5% (95% CI 0.8%-2.2%) in the lower group and 1.8% (95% CI 1.1%-2.5%) in the upper group. Trochanter BMD increased 2.4% (95% CI 1.3%-3.5%) in the lower group and 2.5% (95% CI 1.4%-3.6%) in the upper group (for both analyses time effect P<0.001). At 1 year, a bone resorption marker (C-telopeptide) decreased 9% (P=0.04). Bone formation markers, bone-specific alkaline phosphatase, decreased 5% (P<0.001), and N-terminal type I procollagen peptide decreased 7% (P=0.01). Body composition (percent lean and percent body fat) was maintained in both groups. We concluded that long-term moderate resistance training reversed bone loss, decreased bone turnover, increased femur BMD, and maintained body composition. The similarity of response in upper and lower groups supports a systemic response rather than a site-specific response to moderate resistance training.

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.

HRT provides no additional beneficial effect on sarcopenia in physically active postmenopausal women: a cross-sectional, observational study

OBJECTIVES

Physical activity can prevent or retard the loss of muscle mass associated with aging. On the other hand, it has been suggested that HRT may also help prevent sarcopenia in postmenopausal women. We thus examined if HRT provides additional beneficial effect in physically active postmenopausal women.

METHODS

Forty postmenopausal women aged between 55 and 65 years old (normal weight, healthy and no medication) were recruited. Seventeen women were already taking HRT for at least one year whereas 23 were never submitted to HRT. Body composition was measured by DXA and physical activity metabolism was obtained by the use of accelerometry. Subjects were divided in tertile groups based on their daily physical activity energy expenditure (PAEE).

RESULTS

Physical activity groups were similar for age, HRT users distribution, BMI, trunk fat-free mass (FFM), and all fat mass (FM) components. The group of women who were the most physically active significantly displayed greater total FFM, appendicular FFM, and muscle mass index (MMI) compared to the group of less active women (P < 0.05) whereas HRT added no additional effect on any FFM components.

CONCLUSIONS

Our results suggest that in active postmenopausal women, HRT does not provide any additional beneficial effect on body composition.

Determinants of changes in bone mass and femoral neck structure, and physical performance after menopause: a 9-year follow-up of initially peri-menopausal women

This prospective study set out to determine factors that underlie changes in bone characteristics and physical performance during postmenopausal years. Of 101 peri-menopausal women that originally participated in a randomized, controlled exercise intervention trial, 80 attended the follow-up measurements 9 years later. At follow-up, bone mineral content (BMC) of the lumbar spine, femoral neck and distal radius, as well as the maximal isometric muscle strength of leg extensors and arm flexors, and maximal oxygen uptake, were measured with the same protocols and devices as at the baseline. In addition, the hip structure analysis (HSA) was used to assess changes in the structure and strength at the narrowest section of the femoral neck. Changes in physical fitness or bone characteristics were independent of the original exercise intervention. In general, physical fitness declined with age from 5% to 30% and bone characteristics from 3% to 10%, except for the lumbar spine BMC and the periosteal diameter of the femoral neck, where no changes were observed. The use of hormone therapy (HRT) was the major factor accounting for the maintenance of BMC. Use of HRT alone explained 44% of the variability in the change at the femoral neck BMC, but it was not associated with changes in physical fitness. Change in the body weight was the only factor associated with the change in physical fitness: better maintenance in body weight predicted better maintenance of physical fitness. In conclusion, our results indicate that HRT helps to maintain bone mass and structure, which are important factors in prevention of fragility fractures in later life. However, HRT had no effect on physical fitness, which is highly associated with the risk of falling, the most important cause of fractures.

Effects of eccentric exercise training on cortical bone and muscle strength in the estrogen-deficient mouse

The purpose of this study was to determine whether eccentrically biased exercise training could attenuate changes in muscle and bone function associated with estrogen deficiency in the mouse model. Four groups of ICR mice were used: control (Con), sham ovariectomized (Sham), ovariectomized (OVX), and ovariectomized + high-force resistance training (OVX+Train). All groups except Con were implanted with a nerve cuff surrounding the peroneal nerve to stimulate the left ankle dorsiflexors. Training consisted of 30 stimulated eccentric contractions of the left ankle dorsiflexors at approximately 150% of peak isometric torque every third day for 8 wk. After the training period, groups were not significantly different with regard to peak torque or muscle size. However, the tibial midshaft of the trained leg in the OVX+Train mice exhibited greater stiffness (+15%) than that in the untrained OVX mice, which could not be explained by changes in cross-sectional geometry of the tibia. Scaling of bone mechanical properties to muscle strength were not altered by ovariectomy or training. These data indicate that eccentric exercise training in adult mice can significantly increase bone stiffness, despite the absence of ovarian hormones.

Invited review: Aging and sarcopenia

Aging is associated with progressive loss of neuromuscular function that often leads to progressive disability and loss of independence. The term sarcopenia is now commonly used to describe the loss of skeletal muscle mass and strength that occurs in concert with biological aging. By the seventh and eighth decade of life, maximal voluntary contractile strength is decreased, on average, by 20-40% for both men and women in proximal and distal muscles. Although age-associated decreases in strength per unit muscle mass, or muscle quality, may play a role, the majority of strength loss can be accounted for by decreased muscle mass. Multiple factors lead to the development of sarcopenia and the associated impact on function. Loss of skeletal muscle fibers secondary to decreased numbers of motoneurons appears to be a major contributing influence, but other factors, including decreased physical activity, altered hormonal status, decreased total caloric and protein intake, inflammatory mediators, and factors leading to altered protein synthesis, must also be considered. The prevalence of sarcopenia, which may be as high as 30% for those >/=60 yr, will increase as the percentage of the very old continues to grow in our populations. The link between sarcopenia and disability among elderly men and women highlights the need for continued research into the development of the most effective interventions to prevent or at least partially reverse sarcopenia, including the role of resistance exercise and other novel pharmacological and nutritional interventions.

Effects of estrogen replacement on metabolic factors that influence physical performance in female hypogonadism

There is a lack of knowledge regarding the effects of estrogens on physical performance. This is related, in part, to the challenge of isolating the effects of estrogens from those of progestins, because levels of both hormones fluctuate across the menstrual cycle, both decline during the menopausal transition, and the administration oh hormones to hypogonadal women typically involves a combination of estrogens and progestins. Some research findings suggest that fluctuations in estrogen levels acutely influence factors that may affect physical performance, such as substrate utilization or maximal aerobic power, but solid evidence is lacking. The simple observation that hypogonadism is not uncommon among elite athletes in some sports suggests that estrogen deficiency does not have a major negative impact on athletic performance. However, chronic hypogonadism may ultimately lead to impaired performance by menas that are not necessarily obvious. For example, chronic estrogen deficiency has potent, deleterious effects on the skeleton that can increase risk for stress fracture and may limit the ability to sustain a high level of physical training. Estrogen deficiency also appears to promote fat accumulation and may accelerate the loss of fat-free mass, and both of these changes in body composition could impair physical performance. There is evidence that hormone replacement attenuates the negative effects of hypogonadism on body composition and bone density, and that effects are mediated primarily by estrogens rather than progestins. Further research is necessary to broaden the understanding of the role of the estrogens in physical performance.

Associations of hormone replacement therapy with bone structure and physical performance among postmenopausal women

The purpose of this cohort study was to focus on factors associated with bone mass and structure of lower limbs and physical performance after menopause. Eighty nonsmoking women with a mean age of 62.1 (SD 0.8) years participated in the study. They were classified into two groups by their use of hormone replacement therapy (HRT), either the current users (n = 43) or the never or discontinued users (n = 37). The tibial shaft and distal tibia were scanned with peripheral computed tomography. For the shaft region, the bone mineral content (BMC, g), cortical density (CoD, g/cm(3)), cortical area (CoA, mm(2)), and section modulus (BSI, mm(3)) were determined. For the distal part, the evaluated variables were BMC, total area (ToA), ratio of cortical to total area (CoA/ToA), trabecular density (TrD, g/mm(3)), cortical thickness, BSI, and buckling ratio. Isometric and dynamic muscle strength of the leg extensors, agility and postural sway, and cardiorespiratory capacity (VO(2max)) were measured. Unadjusted values for all bone variables were slightly higher among the HRT users compared to nonusers, with the exception of TrD with no difference. After controlling for body weight, the mean differences (95% confidence interval) remained significant for CoD of the tibial shaft and BSI of the distal tibia, the mean between-group differences being 1.5% (0.4 to 2.5%) and 23.0% (7.1 to 41.3%), respectively. Underlying the greater bending strength, HRT users had thicker cortices and a greater ratio of CoA/ToA. No differences existed between the two study groups for lower limb isometric or dynamic power, cardiorespiratory capacity, or postural balance or sway. HRT may offer protection against bone loss and maintain bone strength, although its ability to improve physical performance is not evident.

Resistance training in postmenopausal women with and without hormone therapy

PURPOSE

The main purpose of this study was to analyze the impact of a 1-yr resistance-training program on body composition and muscle strength in postmenopausal women, and to describe the impact of hormone replacement therapy (HRT) on body composition changes, with and without exercise. Secondarily, we wanted to study dose-response relationships between measures of program compliance and changes in primary outcomes.

METHODS

Subjects were postmenopausal women (40-66 yr) randomly assigned to an exercise (EX) group (N = 117) and a nonexercise group (N = 116). The EX group participated in a 1 yr trainer-supervised resistance-training program, 60-75 min.d-1, 3 d.wk-1. Lean soft tissue (LST) and fat tissue (FT) changes were measured by dual-energy x-ray absorptiometry and strength by one-repetition maximum testing.

RESULTS

Significant (P < 0.001) gains in LST were observed for women who exercised, regardless of HRT status, whereas women who did not exercise lost LST (P < 0.05) if they were not taking HRT, and gained LST (P = 0.08) if they were on HRT. The only significant FT losses were observed for women who exercised while on HRT (P < 0.05). Strength increases were observed at all sites (P < 0.001). Total weight lifted by subjects in their training sessions was a significant predictor of changes in LST (P < 0.001) and strength (P < 0.01).

CONCLUSIONS

Resistance and weight-bearing exercise significantly changed total and regional body composition in postmenopausal women by increasing LST in all women and decreasing FT in women on HRT. Hormone therapy showed no independent effects on body composition, but it protected nonexercising women from losses in LST. The lean and muscle strength changes observed were partially dependent on the volume of training, as expressed by attendance and total weight lifted in 1 yr of training.

Effects of exercise training and hormone replacement therapy on lean and fat mass in postmenopausal women

BACKGROUND

Menopause is associated with decreases in lean mass and increases in fat mass. Serum hormone levels and hormone replacement therapy (HRT) may modify the effects of exercise training on body composition in postmenopausal women.

METHODS

We assessed the changes in total body and regional lean soft tissue and fat mass (using dual-energy x-ray absorptiometry) in 94 sedentary postmenopausal women, aged 40-65 years, after 12 months of resistance and weight-bearing aerobic exercise training. Women currently on oral HRT (n = 39) and not on HRT (n = 55) were randomized within groups to exercise and no exercise, resulting in four groups: exercise + HRT (n = 20), HRT (n = 22), exercise (n = 24), and control (n = 28). Fasting blood samples were measured for resting serum total levels of estrone, estradiol, cortisol, androstenedione, growth hormone, and insulin-like growth factor 1 at baseline and 12 months.

RESULTS

We found significant effects of exercise on increases in total body, arm, and leg lean soft tissue mass, and decreases in leg fat mass and percentage of body fat. There were no interaction effects of exercise and HRT on the changes in muscle strength and body composition. No significant changes in total hormone levels were found after 12 months.

CONCLUSIONS

Exercise training resulted in significant beneficial changes in lean soft tissue and fat mass in early postmenopausal women. These changes in body composition were neither influenced by prolonged HRT use nor accompanied by changes in total levels of the hormones determined in this study.

Muscle performance, sex hormones and training in peri-menopausal and post-menopausal women

Age-related deterioration in muscle performance is one of the major reasons for decreased functional capacity and disability in older people. In women, impaired muscle performance has already been observed during peri-menopause in concert with rapid and dramatic decrease in ovarian hormone production. This observation suggests that female sex steroids may have an important role among other agents in regulating muscle performance in middle-aged and older women. Previous experimental studies have shown that hormone replacement therapy (HRT) and intensive physical training have positive effects on muscle force and explosive power in healthy post-menopausal women. Hormone replacement therapy in combination with physical training may exert even greater gains in muscle performance than HRT and training alone. Despite the significant mean increase in muscle force and power by HRT and/or training, a considerable variability in the individual responses is observed. The mechanism, by which female sex steroids act on muscle performance, is still unclear. Therefore, more research is needed in order to explore all the pathways, by which these steroids could act on skeletal muscle in peri-menopausal and post-menopausal women.

Six months of hormone replacement therapy does not influence muscle strength in postmenopausal women

OBJECTIVES

Postmenopausal hormone replacement therapy (HRT) has positive effects on fracture incidence before any effects on bone mineral density can be demonstrated. This has been attributed to increased muscle strength by HRT. This study was designed to evaluate the effect of 6 months of HRT on muscle strength in postmenopausal women.

METHODS

Forty postmenopausal women, aged 60-78 were included in the study. They were randomly divided in two groups with 20 women in each group. One group received Menorest 50 microg/24 h (estradiol 4.3 mg) and Gestapuran 2.5 mg (medroxyprogesteron) daily and the other group received placebo treatment. The study was conducted as a double blinded, prospective and placebo controlled trial. Hand grip strength, isokinetic knee flexion and extention, and physical activity were measured before treatment, after 3 and 6 months. Physical activity was estimated using a classification system of physical activity. A JAMAR hydraulic hand dynamometer and a Cybex II dynamometer were used to evaluate muscle strength.

RESULTS

Hand grip strength in the right hand, increased significantly in both groups (HRT P<0.001 and placebo P<0.01) and in the left hand in the HRT group (P<0.01). However, there were no differences in muscle strength between the two groups. There was no significant change in isokinetic knee flexion or extension after 6 months in either of the groups. The estimated physical activity increased slightly in the placebo group, but there was no significant difference compared to the treatment group.

CONCLUSIONS

Our data suggest that 6 months of HRT does not influence muscle strength in postmenopausal women.

Relationship between estrogen use and musculoskeletal function in postmenopausal women

OBJECTIVES

The purpose of this study was to examine the relationship between estrogen use and muscle strength, bone mineral density (BMD), and body composition variables in postmenopausal women. Forty healthy, untrained women participated in this study. Subjects (53-65 years) were > or =5 years postmenopausal and were categorized into either estrogen replacement therapy (ERT n=20) or non-estrogen replacement therapy (Non-ERT n=20) groups.

METHODS

Muscular strength was measured by 1-RM testing using Cybex isotonic weight machines. Handgrip strength was measured using a handgrip dynamometer. Diagnostic Ultrasound was used to determine cross-sectional areas of the biceps brachii and rectus femoris muscle groups. BMD of the lumbar spine, proximal femur, and total body was assessed by Dual Energy X-Ray Absorptiometry (Lunar DPX-IQ). Body composition variables were obtained from the total body scan. Serum osteocalcin was measured as an indicator of bone remodeling.

RESULTS

There were no significant differences (P>0.05) for isotonic muscular strength, muscle cross-sectional areas, handgrip strength, or percent fat between ERT and Non-ERT groups. ERT had significantly higher (P<0.05) BMD for the total body, femoral neck and Ward's Area. There were moderate positive relationships between lean body mass and the hip sites (r=0.61-0.70, P<0.05). Regression analyses determined that lean body mass was the strongest predictor of the hip BMD sites. Estrogen use also was a significant predictor for the femoral neck and Ward's Area sites.

CONCLUSION

Women taking estrogen exhibited similar muscular strength, muscle size, and body composition as their estrogen-deficient counterparts. Estrogen use was also associated with higher BMD for the total body and hip sites. Generally, body composition, specifically lean body mass, influenced hip BMD more than muscular strength or estrogen use.

The effect of hormone replacement therapy on appendicular lean tissue mass in early postmenopausal women

OBJECTIVE

The impact of hormone replacement therapy (HRT) on skeletal muscle mass is still a controversial issue in women's health. Some authors hypothesize anabolic effects, others catabolic. These hypotheses, however, await confirmation by longitudinal observations based on more direct measurements of muscle mass. The aim of the present preliminary study was to evaluate the effect of a 3-year HRT program on appendicular lean tissue mass (LTM(A)) in early postmenopausal women aged 45-54 years.

DESIGN

This was a randomized, double-blind and placebo-controlled trial. Women received HRT with 2 mg estradiol valerate combined either continuously with 1 mg cyproterone acetate (days 1-28; n = 15) or sequentially with 75 mug levonorgestrel (days 17-28; n = 15), or placebo (n = 18). Serum estradiol was measured by radioimmunoassay. LTM(A) was measured by dual photon absorptiometry (baseline) and dual energy X-ray absorptiometry (years 2 and 3).

RESULTS

Baseline serum estradiol did not show significant correlation with the respective LTM(A) (r = 0.018, p = 0.88, n = 75). Cross-sectional analysis found no significant differences between the intervention groups at any time points. The longitudinal changes between years 2 and 3 showed a trend toward decreasing LTM(A) in those receiving HRT (-0.08 +/- 0.12 kg, n = 30) compared to those receiving placebo (0.12 +/- 0.25 kg, n = 18, p = 0.44).

CONCLUSIONS

The present preliminary study did not find significant effects on LTM(A) caused by HRT. The trends toward decreasing LTM(A) in the HRT groups might suggest catabolic rather than anabolic effects. These trends, however, await confirmation by larger clinical trials.

Effects of HRT and exercise training on insulin action, glucose tolerance, and body composition in older women

The independent and combined effects of exercise training and hormone replacement therapy (HRT) on body composition, fat distribution, glucose tolerance, and insulin action were studied in postmenopausal women, aged 68 +/- 5 yr, assigned to control (n = 19), exercise (n = 18), HRT (n = 15), and exercise + HRT (n = 16) groups. The exercise consisted of 2 mo of flexibility exercises followed by 9 mo of endurance exercise. HRT was conjugated estrogens 0.625 mg/day and trimonthly medroxyprogesterone acetate 5 mg/day for 13 days. Total and regional body composition were measured by dual-energy X-ray absorptiometry. Serum glucose and insulin responses were measured during a 2-h oral glucose tolerance test. There were significant main effects of exercise on reductions in total and regional (trunk, arms, legs) fat mass, increase in leg fat-free mass, and improvements in glucose tolerance and insulin action. There were significant main effects of HRT on the reduction of total fat mass (HRT, -3.0 +/- 4.0 kg; no HRT, -1.3 +/- 2.6 kg), with a strong trend for reductions in trunk and leg fat mass (both P = 0.07). There was also a significant improvement in insulin action in response to HRT. These results suggest that there are independent and additive effects of exercise training and HRT on the reduction in fat mass and improvement in insulin action in postmenopausal women; the effect of HRT on insulin action may be mediated, in part, through changes in central adiposity.

Aging-related changes in skeletal muscle. Mechanisms and interventions

The aging-related motor handicap and the growing population of elderly citizens have enormous socioeconomic effects on the modern healthcare system. The mechanisms underlying impaired motor performance in old age are complex and involve the central and peripheral nervous systems and the muscle tissue itself. It is widely accepted that the aging-related loss of muscle mass, strength and quality has a significant detrimental impact on motor performance in old age and on the ability to recover from falls, resulting in an increased risk of fractures and dependency. Therefore, the prevention of falls and gait instability is a very important safety issue, and different intervention strategies have been used to improve motor performance among the aging population. There is general consensus that physical exercise is a powerful intervention to obtain long term benefits on muscle function, reduce the frequency of falls, and to maintain independence and a high quality of life in older persons. The results from studies using different types of hormone supplementation therapies have shown interesting and encouraging effects on skeletal muscle mass and function. However, the potential risks with both growth hormone and androgen treatment are not known and long term clinical trials are needed to address safety concerns and the effects on skeletal muscle. Recent advancements in cellular/molecular, physiological and molecular biological techniques will significantly facilitate our understanding of aging-related impairments of muscle function and contribute to the evaluation of different intervention strategies.

Evaluation of the applicability of HRT as a preservative of muscle strength in women

OBJECTIVES

To review the studies that have been undertaken on the effects of postmenopausal hormone replacement therapy (HRT); especially oestrogen (+progestin) regimens on the preservation of muscle strength. Current knowledge of the mechanisms and actions of steroid- and sex hormones on skeletal muscle tissue will be used in an attempt to clarify the mechanism of action of a possible effect. The objective is to arrive at an agreement on whether or not postmenopausal oestrogen administration has a positive influence on skeletal muscle tissue.

METHODS

Peer-reviewed publications were assessed.

RESULTS

An age-related decrement in muscle strength can be found in both men and women. However, in women, an extra decline can be observed around the time of menopause. A possible relationship between the additional diminution in muscle strength and altered hormone concentrations after the onset of menopause has been suggested. Since women nowadays spend one-third of their life postmenopausal, it is extremely important to keep the decline in muscle mass as small as possible. Besides the continuation of a physically active lifestyle, HRT was suggested to serve as a protective mechanism. Although, the usefulness of HRT as a preservative of muscle strength appeared controversial.

CONCLUSIONS

Skeletal muscle strength is sensitive to training up to a high age, though continuation of physical activity does not appear to protect skeletal muscles completely from age-related decrements. Therefore, the development of another preventive method would be useful. Considering the present knowledge it has all the hallmarks that HRT can be a useful tool in the maintenance of muscle strength in postmenopausal women. None the less, further research is necessary to endorse this theory.

Effect of exercise intensity on bone density, strength, and calcium turnover in older women

PURPOSE

This study examined the effects of 24 wk of high intensity strength training or low intensity walking on lumbar bone mineral density (BMD), muscular strength, and calcium turnover in Australian women either taking hormone replacement therapy (HRT) or not taking HRT.

METHODS

A subject pool of 64 women between 45-65 yr and randomly allocated into weights (N = 21), walking (N = 20), weightsHRT (N = 14), and walkingHRT (N = 9) groups completed this study. All subjects trained twice weekly in either a 50-min walking or weight-training program (60-90% IRM). Measurements included maximal isometric knee strength, IRM bench press, IRM squat, isokinetic back strength, lumbar (L2-L4) BMD, serum osteocalcin, and urinary deoxypyridinoline crosslinks (Dpd).

RESULTS

No significant group differences in BMD were evident at the completion of training. However, a significant (P < 0.05) within group change was apparent for the walking group since BMD decreased 1.3% below baseline testing. Osteocalcin levels increased significantly (P < 0.05) in the walking (22%) group. Maximal bench press and squat strength improved significantly (P < 0.05) in the weights (25.8% and 37.7%) and weightsHRT (25.4% and 35.7%) groups. The weights group also increased significantly (P < 0.05) in isokinetic back strength (22.2%).

CONCLUSION

It was concluded that short-term high intensity resistance training provides an effective means for increasing muscular strength in women between 45 and 65 yr. The training effects on lumbar BMD were not apparent in the present study.

Food restriction suppresses muscle growth and augments osteopenia in ovariectomized rats

We examined effects of 4 wk of food restriction on ovariectomy-related changes in muscle, bone, and plasma insulin-like growth factor I (IGF-I). Female Sprague-Dawley rats (7 mo old) were assigned to freely eating groups: sham-operated (Sham), ovariectomized (Ovx-AL), and estrogen (estradiol)-replaced Ovx (Ovx+E(2)). Ovx rats were also pair fed with Sham (Ovx-PF) or weight matched with Sham by food restriction (Ovx-FR). Ovx-AL and Ovx-PF rats had similar estrogen status and body weight; therefore, the groups were combined (group: Ovx). After treatment, body weight was approximately 10% greater in Ovx than in Sham rats (P < 0.05), and muscle weight-to-body weight ratios were comparable among all groups. Bone mineral contents of whole tibiae in Ovx-FR and Ovx were approximately 15% (P < 0.05) and approximately 6% lower than in Sham rats (P < 0.05), respectively. Plasma IGF-I was approximately 30% higher in Ovx than in Sham (P < 0.05) but was similar between Sham and Ovx-FR. IGF-I was highly correlated with body weight and muscle mass. Within non-estrogen-replaced Ovx rats, IGF-I explained approximately 19% of variance in bone mineral content after accounting for variance attributable to body weight. Findings suggest that estrogen acts indirectly on skeletal muscle and bone in rats through regulation of body growth by factors such as IGF-I.

Physical activity and the progressive change in body composition with aging: current evidence and research issues

PURPOSE

The purpose was to review studies that have examined the effect of aerobic (AEX) or resistance exercise (REX) on body composition in older individuals (>55 yr). Our goal was to examine the effect of these two exercise paradigms on fat mass and fat-free mass and to consider those factors that may explain variability in findings among studies.

METHODS

We conducted a literature search (Medline, 1984-1999) for intervention studies (at least 2 months in duration) that have examined the independent effect of either REX or AEX on body composition in older individuals.

RESULTS

AEX decreased fat mass (range: -0.4 to -3.2 kg) but had little effect on fat-free mass. The change in fat mass with AEX was related to the duration of the exercise program (r = 0.51; P < 0.02) but not to body composition methodology. In contrast, REX reduced fat mass (range: -0.9 to -2.7 kg) and increased fat-free mass (range: 1.1 to 2.1 kg). Changes in body composition with REX were not related to body composition methodology or the duration of the exercise program.

CONCLUSION

Both AEX and REX appear to be beneficial in reducing body fat. REX appears to have the additional benefit of increasing fat-free mass.

Long-term recreational gymnastics, estrogen use, and selected risk factors for osteoporotic fractures

The purpose of this cross-sectional study was to examine whether long-term participation in recreational gymnastics or folk dancing or estrogen replacement therapy (ERT) is associated with mechanically more competent bones and improved muscular strength and body balance. One hundred and seventeen healthy, female postmenopausal recreational gymnasts (mean age 62.1 [SD 4.7] years) and 116 sedentary controls (mean age 61.5 [4.6] years) were enrolled in the study. Bone mineral content (BMC) of the distal radius, femoral neck, and trochanter were measured with dual-energy X-ray absorptiometry. BMC of the midshaft and distal tibia and trabecular density (TrD) of the distal tibia were measured with peripheral computed quantitative tomography. Maximal isometric strength, muscular power, cardiorespiratory fitness, and body balance of the participants were also assessed. The cardiorespiratory fitness, muscular strength, and dynamic balance of the recreational gymnasts and folk dancers combined were significantly better than those of the controls, the average group difference ranging from 7.5% (95% confidence interval 5.0-9.9%) in dynamic balance to 12.8% (6.6-19. 4%) in dynamic muscular power. ERT was not associated with the fitness indicators, muscular power, or balance, but was significantly associated with the BMC at all the measured bone sites, the mean group difference between estrogen users and nonusers ranging from 6.5% (3.7-9.3%) for the tibial shaft to 11.8% (6.4-17. 0%) for the distal radius. Recreational gymnastics, in turn, was significantly associated with higher BMC at the tibia only, the mean group difference being 3.9% (0.9-6.9%) for the tibial shaft and 7.7% (3.7-11.9%) for the distal tibia. Recreational gymnastics was also associated with higher TrD at the distal tibia (5.2%; 1.2-9.2%), whereas estrogen usage did not show such association. The results indicate that ERT seems especially effective in preventing postmenopausal bone loss, whereas recreational gymnastics and folk dancing improve muscular performance and body balance in addition to increased bone mass and bone size in the tibia. All these factors are essential in prevention of fall-related fractures of the elderly.

Effects of ovariectomy and hindlimb unloading on skeletal muscle

Female rats (7-8 mo old, n = 40) were randomly placed into the intact control (Int) and ovariectomized control (Ovx) groups. Two weeks after ovariectomy, animals were further divided into intact 2-wk hindlimb unloaded (Int-HU) and ovariectomized hindlimb unloaded (Ovx-HU). We hypothesized that there would be greater hindlimb unloading-related atrophy in Ovx than in Int rats. In situ contractile tests were performed on soleus (Sol), plantaris (Plan), peroneus longus (Per), and extensor digitorum longus (EDL) muscles. Body weight and Sol mass were approximately 22% larger in Ovx than in Int group and approximately 18% smaller in both HU groups than in Int rats (Ovx x HU interaction, P < 0.05), and there was a similar trend in Plan muscle (P < 0.07). There were main effects (P < 0.05) for both ovariectomy (growth) and hindlimb unloading (atrophy) on gastrocnemius mass. Mass of the Per and EDL muscles was unaffected by either ovariectomy or hindlimb unloading. Time to peak twitch tension for EDL and one-half relaxation times for Sol, Plan, Per, and EDL muscles were faster (P < 0.05) in Ovx than in Int animals. The results suggest that 1) ovariectomy led to similar increases of approximately 20% in body weight and plantar flexor mass; 2) hindlimb unloading may have prevented ovariectomy-related muscle growth; 3) greater atrophy may have occurred in Sol and Plan of Ovx animals compared with controls; and 4) removal of ovarian hormonal influence decreased skeletal muscle contraction times.

HRT preserves increases in bone mineral density and reductions in body fat after a supervised exercise program

The aims of this study were to confirm our previous finding that hormone-replacement therapy (HRT) augments exercise-induced increases in bone mineral density (BMD) in older women and to determine whether HRT preserves the adaptations when exercise is reduced or discontinued. The study included an 11-mo treatment phase and a 6-mo follow-up phase. Participants, aged 66 +/- 3 yr, were assigned to control (Con; n = 10), exercise (Ex; n = 18), HRT (n = 10), and Ex+HRT (n = 16) groups. HRT was continued during the follow-up. After the treatment phase, changes in total body BMD were -0.5 +/- 1.7, 1.5 +/- 1.4, 1.2 +/- 0.8, and 2.7 +/- 1.2% in Con, Ex, HRT, and Ex+HRT, respectively. Ex+HRT was more effective than HRT in increasing BMD of the total body and tended (P = 0.08) to be more effective at the lumbar spine. Ex+HRT was more effective than Ex in increasing BMD of the total body, lumbar spine, and trochanter. Exercise-induced gains in BMD were preserved during the follow-up only in those individuals on HRT. HRT also attenuated fat accumulation, particularly in the abdominal region, after the exercise program. These findings suggest that HRT is an important adjunct to exercise for the prevention not only of osteoporosis but also of diseases related to abdominal obesity.