Relationship of menopause to skeletal and muscle mass

Differential effects of oral estrogen versus oral estrogen-androgen replacement therapy on body composition in postmenopausal women

Menopause is associated with decreased lean body mass and increased fat due to aging and declining hormone secretion. Estrogens or estrogen-progestins have been used to alleviate vasomotor symptoms. However, estrogen-androgen (E/A) therapy is also used for vasomotor symptom relief and has been shown to increase lean body mass while decreasing fat mass. The objective of this 16-wk, double-blind, randomized, parallel group clinical trial was to compare esterified estrogen plus methyltestosterone (1.25 mg estrogen + 2.5 mg methyltestosterone/d; E/A group) vs. esterified estrogen alone (1.25 mg/d; E group) on body composition. Forty postmenopausal women (mean age, 57 yr) participated. Compared with estrogen treatment alone, women in the E/A group increased their total lean body mass and reduced their percentage fat for all body parts (P < 0.05). After E/A treatment, there were statistically significant increases in lean body mass by 1.232 kg [0.181 +/- 0.004, 0.81 +/- 0.057, and 0.24 +/- 0.009 kg in the upper body (P = 0.021), trunk (P = 0.001), and lower body (P = 0.047), respectively]. In the E group, the increase was 0.31 +/- 0.004, 0.021 +/- 0.03, and 0.056 +/- 0.05 kg in the upper body, trunk, and lower body, respectively. In the E/A group, body fat was reduced by 0.90 kg (P = 0.18 for the trunk only), and percentage body fat declined by 7.4% (P < or = 0.05 for all body parts). Lower body strength increased by 23.1 kg (51 lb) in the E/A group vs. only 11 kg (24.25 lb) in the E group (P = 0.002 between groups). A statistically significant increase in weight (2.7 +/- 5.1 vs. 0.1 +/- 4.6 lb; P < 0.05) was observed in the E/A group compared with the E group. When subjects were given self-reporting questionnaires, more improvement was noted in sexual functioning and quality of life in the E/A group when compared with patients receiving E alone. There were no noteworthy side effects. In conclusion, E/A replacement therapy can improve body composition, lower-body muscle strength, quality of life, and sexual functioning in postmenopausal women.

Androgen effects on bone and muscle

Bone health and strength are dependent on the coupling of cone resorption and bone formation. This process is governed by the interaction of osteoclasts and osteoblasts plus the modulating influence of the bone mechanicosensory cells-the osteocytes. Both sex steroids-estrogen (E) and testosterone (T)- have receptors on all bone cells, with androgen dominance on osteoblasts and osteocytes. Specific receptors for the weaker androgens, such as DHEA have also been identified. The activity of the sex steroids, influenced by various enzymes found in bone, is reflective of the hormone ligand before its binding to the bone cells. As a result, T acts both directly and via its aromatization to estradiol. The activity of the androgens also varies with the bone surface; periosteal cells, for example, do not have 5alpha-reductase activity, indicating that T is the active metabolite at this clinically important site. Androgens influence bone cell function via local and systemic growth factors and cytokines. By enhancing osteoblast differentiation, androgens regulate bone matrix production, organization, and mineralization. Androgens also regulate osteoclast recruitment and activity. Endogenous androgens increase bone mineral density (BMD) in both adolescent and adult premenopausal women. Women with excess endogenous androgen-for example, those with hirsutism and polycystic ovary syndrome (PCOS)-have increased BMD compared with normal young women. E and androgen therapy increases BMD to a greater degree than does E therapy alone. This is true for both oral combinations of esterified E and methyltestosterone and for subcutaneous T implants. Androgenic progestins have an additive effect on BMD when combined with E therapy and have the further advantage of being protective to the endometrium in E-treated women. Androgens increase muscle mass and strength. The resulting improvement in physical activity leads to the activation of bone-forming sites and the stimulation of the bone formation-modulating cells, the osteocytes. Mechanical loading, when combined with hormone therapy, results in greater osteogenic response than does either alone.

Habitual physical activity, anabolic hormones, and potassium content of fat-free mass in postmenopausal women

BACKGROUND

Total body potassium (TBK) is known to decline throughout adulthood. The relations between physical activity, age, anabolic hormones, and TBK have rarely been considered.

OBJECTIVE

We sought to describe the relation between habitual physical activity, age, serum estradiol, and insulin-like growth factor I (IGF-I) and TBK in postmenopausal women.

DESIGN

TBK, fat-free mass (FFM), moderate-to-vigorous-intensity physical activity (MVPA; assessed with use of a semistructured interview), and serum concentrations of estradiol, IGF-I, and IGF binding protein 3 (IGFBP-3) were quantified in 51 healthy white women aged 54-76 y.

RESULTS

The potassium content of FFM declined curvilinearly with age, indicating an accelerated loss of skeletal muscle after 65 y of age. With the data split into high (n = 25) and low (n = 26) MVPA groups, the active women had 6.5% more potassium per FFM than did their less-active counterparts (P < 0.01). In multiple regression analysis, MVPA was the major determinant of the potassium content of FFM (P = 0.02), such that an active 70-y-old had the potassium content value of a 55-y-old sedentary woman. Serum estradiol, IGF-I, and IGFBP-3 were not significant determinants of the potassium content of FFM.

CONCLUSIONS

These data suggest that 1) habitual physical activity can significantly influence FFM potassium content; 2) physical activity must, therefore, be considered if the effect of aging per se on TBK is to be clarified; and 3) MVPA, such as that pursued by the active women in the present study (eg, walking, dancing, floor exercises, and swimming), can assist in preventing sarcopenia in older women.

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.

Race and sex effects on the association between muscle strength, soft tissue, and bone mineral density in healthy elders: the Health, Aging, and Body Composition Study

Two factors generally reported to influence bone density are body composition and muscle strength. However, it is unclear if these relationships are consistent across race and sex, especially in older persons. If differences do exist by race and/or sex, then strategies to maintain bone mass or minimize bone loss in older adults may need to be modified accordingly. Therefore, we examined the independent effects of bone mineral-free lean mass (LM), fat mass (FM), and muscle strength on regional and whole body bone mineral density (BMD) in a cohort of 2,619 well-functioning older adults participating in the Health, Aging, and Body Composition (Health ABC) Study with complete measures. Participants included 738 white women, 599 black women, 827 white men, and 455 black men aged 70-79 years. BMD (g/cm2) of the femoral neck, whole body, upper and lower limb, and whole body and upper limb bone mineral-free LM and FM was assessed by dual-energy X-ray absorptiometry (DXA). Handgrip strength and knee extensor torque were determined by dynamometry. In analyses stratified by race and sex and adjusted for a number of confounders, LM was a significant (p < 0.001) determinant of BMD, except in white women for the lower limb and whole body. In women, FM also was an independent contributor to BMD at the femoral neck, and both FM and muscle strength contributed to limb BMD. The following were the respective beta-weights (regression coefficients for standardized data, Std beta) and percent difference in BMD per unit (7.5 kg) LM: femoral neck, 0.202-0.386 and 4.7-5.9%; lower limb, 0.209-0.357 and 2.9-3.5%; whole body, 0.239-0.484 and 3.0-4.7%; and upper limb (unit = 0.5 kg), 0.231-0.407 and 3.1-3.4%. Adjusting for bone size (bone mineral apparent density [BMAD]) or body size BMD/height) diminished the importance of LM, and the contributory effect of FM became more pronounced. These results indicate that LM and FM were associated with bone mineral depending on the bone site and bone index used. Where differences did occur, they were primarily by sex not race. To preserve BMD, maintaining or increasing LM in the elderly would appear to be an appropriate strategy, regardless of race or sex.

Relationship between total and regional bone mineral density and menopausal state, body composition and life style factors in overweight Japanese women

OBJECTIVE

To investigate whether menopausal state, body composition and lifestyle factors influence total and regional bone mineral density in overweight Japanese women.

DESIGN

Cross-sectional study of women who were recruited to the weight reduction program held at community-based health promotion center in Tokyo area.

SUBJECTS

A total of 178 women with a mean age of 48 y old (20-69 y) with a clear menstrual history and BMI over 24.

MEASUREMENTS

Total, regional and lumbar spine bone mineral density (BMD) and body composition were measured using DXA (Lunar). Menstrual history was taken by a questionnaire and walking steps per day and energy intake were measured. Physical fitness was assessed by cardio-respiratory fitness and leg extension power. Subjects were divided into pre-menopausal and post-menopausal groups.

RESULTS

Pre-menopausal group had significantly higher total body BMD as well as regional BMD than post-menopausal group. However, no differences in BMI, percentage fat and fat mass (FM) were seen between the two groups. The multiple regression analysis stepwise method revealed that total and regional BMD correlated with menopausal state and total FM independently. Total and regional BMD did not correlate with total non-fat soft tissue mass (NFSM), energy intake, walking steps or physical fitness levels. Trunk and lower extremities BMD correlated with corresponding regional FM and NFSM, and upper extremities BMD correlated with only corresponding body part NFSM after adjusting menopausal state.

CONCLUSION

Total and regional BMD had strong negative correlation with menopausal state rather than total FM in overweight Japanese women. Weight-bearing site BMD correlated with corresponding body part FM and NFSM and non-weight bearing site BMD only correlated with corresponding body part NFSM after adjusting for menopausal state.

Comparison of soft tissue body composition in postmenopausal women with or without hormone replacement therapy considering the influence of reproductive history and lifestyle

OBJECTIVES

To examine long-term effects of at least 5 years' conventional hormone replacement therapy (HRT), reproductive history and lifestyle on fat mass and muscle mass in postmenopausal women.

RESEARCH DESIGN AND METHODS

A cross-sectional retrospective approach was used, including 64 healthy women (56-69 years, mean age 63.4 years). Hormone users were compared with age-matched non-users with respect to (a) type of HRT used (oestrogen vs oestrogen plus gestagen vs no hormones), (b) categories of oestrogens used (oestradiol-based oestrogens vs conjugated equine oestrogens vs no oestrogens) and (c) categories of gestagens used (testosterone derivatives vs progesterone derivatives vs no gestagens). Data on hormone use, reproductive history (age at menarche, age at menopause, number of years postmenopausal, number of children) and lifestyle (physical activity level, alcohol consumption, smoking habits) were collected by questionnaires. Body composition was analysed by multiple-frequency bioelectrical impedance analysis, estimating fat mass, fat-free mass and body cell mass as absolute values (FM, FFM, BCM, respectively) and percentages of body weight (%FM, %FFM, %BCM).

RESULTS

Analysis of covariance, adjusting body composition variables for body mass index, showed that (a) unopposed oestrogen users, oestrogen plus gestagen users and non-users did not differ significantly in body composition variables, (b) users of oestradiol-based oestrogens had significantly more BCM than oestrogen abstainers (p < 0.05), (c) users of testosterone-based gestagens had more BCM than gestagen abstainers (p = 0.05). Stepwise multiple regression analyses, including HRT-related, reproductive and lifestyle variables, indicated that the duration of HRT (p < 0.05) and physical activity level (p = 0.01) were significant positive predictors of %BCM, whereas the number of children significantly positively predicted FM and %FM (each p < 0.05). No significant associations between fat-free mass and HRT were found.

CONCLUSIONS

The results suggest that conventional doses of oestrogens and gestagens used in HRT might be a factor in preserving muscle mass after long-term administration. It is recommended that BCM is used instead of FFM as an indicator of muscle mass. Studies relating muscle mass to HRT in postmenopausal women should consider physical activity as a possible confounding variable.

Sarcopenia: current concepts

Sarcopenia, the loss of muscle mass and strength with age, is becoming recognized as a major cause of disability and morbidity in the elderly population. Sarcopenia is part of normal aging and does not require a disease to occur, although muscle wasting is accelerated by chronic diseases. Sarcopenia is thought to have multiple causes, although the relative importance of each is not clear. Neurological, metabolic, hormonal, nutritional, and physical-activity-related changes with age are likely to contribute to the loss of muscle mass. In this review, we discuss current concepts of the pathogenesis, treatment, and prevention of sarcopenia.

Serum IGF-I is higher in gymnasts than runners and predicts bone and lean mass

INTRODUCTION

We examined the relationships between insulin-like growth factor I (IGF-I), its binding protein (IGFBP-3), body composition, and bone mineral density (BMD) in collegiate runners (N = 13), gymnasts (N = 10), and noncompetitive women (N = 10).

METHODS

Subjects were evaluated by dual-energy x-ray absorptiometry for body composition and BMD of the spine, hip, and whole body, fasting serum levels of IGF-I and IGFBP-3, and dietary intake. The ratio IGF-I/IGFBP-3 was calculated as a marker of IGF-I bioavailability.

RESULTS

In ANOVA, IGF-I and IGF-I/IGFBP-3 in athletes with oligomenorrhea and amenorrhea did not differ from eumenorrheic athletes; thus, values were pooled. Lean/height2 and bone mass at the hip and spine were higher in gymnasts than runners and controls. Total caloric intake was similar between groups. IGF-I and IGF-I/IGFBP-3 differed between groups with gymnasts having higher IGF-I values than runners (397+/-58 vs 288+/-73 ng x mL(-1), P < 0.001) and higher IGF-I/IGFBP-3 than controls and runners (0.065+/-0.009 vs 0.056+/-0.008 vs 0.045+/-0.009, P = 0.0001). In simple regression, IGF-I and IGF-/IGFBP-3 were related to lean/height2 and BMD of the lumbar spine and hip (P < 0.01-0.0001). IGF-I and IGF-I/IGFBP-3 were multicollinear; thus, the ratio was used in subsequent stepwise regression. Lean mass, corrected for body surface area (height2), independently predicted spine and trochanteric BMD (R2 = 0.26, 0.28, respectively), whereas IGF-I/IGFBP-3 and lean/height2 together contributed to 48% of the variance in femoral neck BMD.

CONCLUSION

We conclude that, in this group of young adult women, lower BMD in runners may be due, in part, to lower levels of IGF-I and the ratio of IGF-I-to-IGFBP-3 and that IGF-I may mediate the relationship between bone and lean mass.

The effects of physical exercise on body fat distribution and bone mineral density in postmenopausal women

OBJECTIVE

The present cross-sectional study investigated the effects of physical exercise on body fat distribution and bone mineral density (BMD).

METHODS

Subjects were 57 postmenopausal women (mean age, 60.5+/-6.4 years) who had exercised regularly for at least 2 years. Controls were 130 age-matched sedentary women. Age, years since menopause (YSM), height, weight, and body mass index (BMI, wt./ht.(2)) were recorded. Total fat mass, percentage of body fat, trunk fat mass, leg fat mass, the ratio of trunk fat mass to leg fat mass (trunk-leg fat ratio), total body lean mass, percentage of body lean, and lumbar spine BMD (L2-L4) were measured by dual-energy X-ray absorptiometry.

RESULTS

Baseline characteristics and leg fat mass did not differ between the two groups. Total fat mass, percentage of body fat, trunk fat mass, and trunk-leg fat ratio were lower (P<0.05, P<0.01, P<0.01 and P<0.001, respectively), while total body lean mass, percentage of body lean mass, and lumbar spine BMD were higher in exercising women (P<0.05, P<0.05 and P<0.01, respectively). Performing physical exercise was inversely correlated with trunk-leg fat ratio (standardized regression coefficient=-0.178, P<0.01), but positively correlated with BMD (0. 203, P<0.01) irrespective of age, height, YSM, and total fat mass.

CONCLUSION

Physical exercise has beneficial effects on body fat distribution and BMD in postmenopausal women. Reduction of upper body fat distribution with physical exercise may be more attributable to the decrease in trunk fat mass.

Composição corpórea, distribuição de gordura e metabolismo de repouso em mulheres histerectomizadas no climatério: há diferenças de acordo com a forma da administração do estrogênio?

As mulheres no climatério sofrem inúmeras alterações metabólicas, cardiovasculares e de composição corporal. A terapêutica de reposição hormonal (TRH) vem alcançando importância na atualidade, tornando-se quase um consenso que a mulher após a menopausa deve receber hormônios, pelos benefícios que trazem para a saúde, tais como prevenção de doenças coronarianas e osteoporose. A forma de administração de estrogênios influi em uma série de parâmetros metabólicos; é sabido, por exemplo, que a administração oral provoca uma elevação no hormônio de crescimento (GH) e uma diminuição do IGFI: quanto à forma (transdérmica), os estudos ainda não são conclusivos quanto aos níveis do GH e IGFI. Por outro lado, o GH e o IGFI podem agir de maneiras diferentes no metabolismo lipídico, ósseo e na distribuição de gordura corpórea. O objetivo deste trabalho foi estudar as variações da distribuição visceral de gordura nas diferentes formas de administração estrogênica e, particularmente, verificar se a forma de administração do hormônio altera a quantidade de gordura visceral. Foram estudadas 33 mulheres no climatério, histerectomizadas, divididas em 3 grupos: 1) 13 pacientes recebendo estrogênio eqüino conjugado 0,625mg via oral diariamente; 2) 10 pacientes recebendo 17b estradiol TTS 50 2x/semana via transdérmica e; 3) 10 pacientes recebendo placebo. Estas pacientes foram submetidas: a) análise da composição corporal pelos métodos de bioimpedância (RJL 101-A) e densitometria óssea e corpórea (DEXA); b) análise da distribuição de gordura, particularmente de adiposidade visceral, pela tomografia computadorizada abdominal e; c) medida do metabolismo de repouso pelo calorímetro DELTA-TRAC. Foram ainda feitas dosagens laboratoriais de colesterol total e frações, triglicérides e glicemia aos 0,6 e 12 meses. Não observamos diferenças estatística significativas nos parâmetros estudados em nenhum dos 3 grupos (placebo, estrógeno oral e estrogênio transdérmico), embora notamos tendência a maior ganho de peso nos grupos com estrógenos e tendência a maior ganho de massa magra no grupo com estrogênio transdérmico.

Difference in the effect of adiposity on bone density between pre- and postmenopausal women

OBJECTIVES

Elevated bone mineral density (BMD) in obese women is partially attributable to the higher circulating estrogen levels derived from extraglandular aromatization in adipose tissue. However, it remains unclear whether there is an effect of overall adiposity on BMD in both pre- and postmenopausal women. The difference in the effect of overall adiposity on BMD between pre- and postmenopausal women was investigated.

MATERIALS AND METHODS

Subjects were 296 premenopausal women with regular menstruation and 233 postmenopausal women. Age, age at menarche, years since menopause (YSM, in postmenopausal women), weight, height, and body mass index were recorded. Total fat mass amount, lean mass amount, and percentage of body fat were measured by whole body scanning with dual-energy X-ray absorptiometry (DEXA). Lumbar spine BMD (L2-L4) was measured by DEXA. In each group, significant determinants of BMD were investigated using univariate and stepwise multiple regression analysis.

RESULTS

In postmenopausal women, YSM, lean mass amount, total fat mass amount, and height were significant determinants of BMD (R(2)=0.273, P<0.001). In premenopausal women, only two variables including lean mass amount and age at menarche were significant determinants of lumbar spine BMD (R(2)=0.110, P<0.001), but total fat mass amount and percentage of body fat were not significant determinants of BMD.

CONCLUSION

The effect of overall adiposity on BMD is more prominent in postmenopausal women than in premenopausal women.

Effect of menopausal status on body composition and abdominal fat distribution

OBJECTIVE

Preliminary studies suggest that the menopause transition is associated with deleterious changes in body composition and abdominal fat distribution. Limitations of the methodology used in these studies, however, render their conclusions controversial. Thus, the present study used radiologic imaging techniques to examine the effect of menopausal status on body composition and abdominal fat distribution.

DESIGN

Cross-sectional.

SUBJECTS

Fifty-three healthy, middle-aged, premenopausal women (mean+/-SD; 47+/-3 y) and 28 early-postmenopausal women (51+/-4 y).

MEASUREMENTS

Total and regional body composition by dual energy X-ray absorptiometry and abdominal fat distribution by computed tomography.

RESULTS

No differences in total body fat-free mass or appendicular skeletal muscle mass were noted between groups. In contrast, total body fat mass was 28% higher (23+/-7 vs 18+/-7 kg) and percentage fat 17% higher (35+/-6 vs 30+/-9%; both P<0.01) in postmenopausal women compared with premenopausal women. Postmenopausal women had a 49% greater intra-abdominal (88+/-32 vs 59+/-32 cm2; P<0.01) and a 22% greater abdominal subcutaneous fat area (277+/-93 vs 227+/-108 cm2; P<0.05) compared to premenopausal women. The menopause-related difference in intra-abdominal fat persisted (P<0.05) after statistical adjustment for age and total body fat mass, whereas no difference in abdominal subcutaneous fat was noted. A similar pattern of differences in total and abdominal adiposity was noted in sub-samples of pre- and postmenopausal women matched for age or fat mass.

CONCLUSION

Our data suggest that early-postmenopausal status is associated with a preferential increase in intra-abdominal fat that is independent of age and total body fat mass. International Journal of Obesity (2000) 24, 226-231

Relation between body composition and biochemical markers of bone turnover among early postmenopausal women

We studied the associations between body composition and biochemical markers of bone formation and resorption among 1600 postmenopausal women, ages 45-59. Multiple regression analyses were performed to examine the independent associations of fat mass, muscle strength (quadriceps strength), height, and whole body bone mineral content (BMC) with biochemical markers of bone formation (serum osteocalcin) and resorption (urinary type I collagen crosslinked N-telopeptides [NTX]). Per interquartile range (IQR) (the difference between 75th and 25th percentiles) increase in fat mass and whole body BMC, the mean levels of osteocalcin decreased by 3% and 13%, respectively; NTX decreased by 5 and 21%. Fat mass and whole-body BMC were also significantly associated with decreases in the average of osteocalcin and NTX Z-scores. By contrast, the mean levels of serum osteocalcin increased by 2 and 11%, respectively, per IQR increase in muscle strength and height; NTX increased by 4 (not significant) and 14%, respectively. Both muscle strength and height were significantly associated with increases in the average Z-scores. These exploratory analyses suggest that fat mass and whole-body BMC were associated with decreased bone turnover, while muscle strength and height were associated with increased bone turnover.

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.

Protective effect of estrogens against oxidative damage to heart and skeletal muscle in vivo and in vitro

Estrogen has been shown to protect skeletal muscle from damage and to exert antioxidant properties. The purpose of the present study was to investigate the antioxidant and protective properties of estrogens in rodent cardiac and skeletal muscle and H9c2 cells. Female Sprague-Dawley rats were separated into three groups, ovariectomized (OVX), ovariectomized with estrogen replacement (OVX + E2), and intact control (SHAM), and were assessed at two time periods, 4 and 8 weeks. Rodents hearts were analyzed for basal and iron-stimulated lipid peroxidation in the absence and presence of beta-estradiol (betaE2) by measuring thiobarbituric acid reactive species (TBARS). Isolated soleus (SOL) and extensor digitorum longus (EDL) were analyzed for creatine kinase (CK) efflux. Using H9c2 cells, the in vitro effects of betaE2 and its isomer alpha-estradiol were investigated under glucose-free/hypoxic conditions. TBARS assay was also performed on the H9c2 in the presence or absence of betaE2. The results indicate that OVX rodent hearts are more susceptible to lipid peroxidation than OVX + E2 hearts. OVX soleus showed higher cumulative efflux of CK than OVX + E2. Furthermore, H9c2 survival during oxidative stress was enhanced when estrogen was present, and both OVX hearts at 4 weeks and H9c2 cells particularly were protected from oxidative damage by estrogens. We conclude that estrogen protects both skeletal and cardiac muscle from damage, and its antioxidant activity can contribute to this protection.

The contribution of menopause to changes in body-fat distribution

OBJECTIVE

To investigate whether menopause contributes to changes in body-fat distribution, irrespective of aging or obesity.

METHODS

The subjects were 545 premenopausal (aged 16-55 years; mean +/- standard deviation, 37.7 +/- 9.1 years) and 219 postmenopausal (aged 45-65 years, 58.0 +/- 5.0 years) women. Baseline characteristics included age, body mass index (BMI), and menopausal status (premenopause or postmenopause). The ratio of trunk fat to leg fat (trunk-leg ratio) was estimated by dual-energy X-ray absorptiometry. The trunk-leg ratio and baseline characteristics were compared between the 2 groups. In all subjects (n = 764), possible correlations between the trunk-leg ratio and the baseline characteristics were determined using univariate and multivariate analysis. In postmenopausal women, the relationship of the trunk-leg ratio to YSM or age after adjusting for BMI was investigated.

RESULTS

The trunk-leg ratio and BMI were significantly higher in postmenopausal women than in premenopausal women. In all subjects, age and BMI were positively correlated with the trunk-leg ratio (r = 0.445 and 0.587, respectively, p < 0.0001). Menopause was also positively correlated with the trunk-leg ratio on univariate regression analysis (standardized regression coefficient = 0.369, p < 0.0001). On multiple regression analysis, age, BMI, and menopause were independently correlated with the trunk-leg ratio (p < 0.05). In postmenopausal women, age and YSM were positively correlated with the trunk-leg ratio, independent of the BMI (p < 0.01).

CONCLUSIONS

Menopause contributes to a change in body-fat distribution, irrespective of aging or obesity.

Aging, body composition, and lifestyle: the Fels Longitudinal Study

BACKGROUND

Changes in body composition in men and women occur with age, but these changes are affected by numerous covariate factors.

OBJECTIVE

The study examined patterns of change in body composition and determined the effects of long-term patterns of change in physical activity in older men and women and in menopausal status and estrogen use in women.

DESIGN

Serial measures of height, weight, body mass index (BMI), total body fat (BF), percentage BF, and fat-free mass (FFM) from underwater weighing of 102 men and 108 women enrolled in the Fels Longitudinal Study were analyzed. Physical activity levels and menopausal status were included as covariates.

RESULTS

There were significant age-related decreases in FFM and height and increases in total BF, percentage BF, weight, and BMI. Physical activity was associated with decreases in total BF, percentage BF, weight, and BMI in men and were associated with increases in FFM and decreases in total BF and percentage BF in women. Postmenopausal women had significantly higher total BF and percentage BF than did pre- and perimenopausal women. The longer the time since menopause the greater were the increases in weight, BMI, total BF, and percentage BF; however, estrogen use attenuated these increases.

CONCLUSIONS

Low FFM can be improved by increased physical activity. The effects of an intervention program on body composition can be masked if only body weight or BMI is measured. The effects of physical activity were more profound in postmenopausal than in premenopausal women, and estrogen use had beneficial effects on body composition.

Perspectives on bone mechanical properties and adaptive response to mechanical challenge

The bones of the human skeleton serve a mechanical function besides providing a reservoir for calcium and hematopoietic homeostatis. When mechanically challenged, they usually respond and adapt; failure to do so can result in fracture. The mechanical behavior of bone is determined by bone mass and its material properties and by its geometry and architecture. Therefore, in vivo noninvasive measurements of bone mass, geometry, and structure can predict bone strength and are usually employed as a useful-if not always reliable-way to estimate bone fragility, whereas direct bone biomechanical testing in vitro can provide detailed information about mechanical strength. Because bone strains are likely to be regulators of bone mass and strength, exercise protocols designed to counteract the effects of osteoporosis should load the target bone with repeated high peak forces and high strain rates or high impacts on a long-term basis. Such a protocol creates varied strain distributions throughout the bone structure, producing short, repeated strains on the bone in directions to which it is unaccustomed. Exercise in this manner can maintain and perhaps increase bone mass and improve mechanical properties and neuromuscular competency, reducing skeletal fragility and the predisposition to falls.

The effect of menopause on regional and total body lean mass

OBJECTIVES

To investigate the effect of menopause on regional and total body lean mass.

METHODS

Evaluation of 123 healthy premenopausal women (40.6 +/- 10.8 years) and 123 healthy postmenopausal women (61.8 +/- 7.5 years). All subjects were right side dominant. Regional (head, bilateral arms, trunk, and bilateral legs) and total body lean mass were measured using whole-body scanning by dual-energy X-ray absorptiometry. Baseline characteristics including age, height, weight, and menopausal state were recorded. These variables were compared between pre- and postmenopausal women. In all subjects, correlations between regional or total body lean mass and baseline characteristics were investigated using univariate and multiple regression analyses.

RESULTS

Height, and lean mass of the trunk, bilateral legs and total body were significantly lower in postmenopausal women than in premenopausal women, while lean mass of the bilateral arms did not differ between the two groups. On univariate regression analysis, bilateral arms lean mass was positively correlated with height (P < 0.001). Trunk, bilateral legs, and total body lean mass were inversely correlated with age and menopausal state (P < 0.001), but were positively correlated with height (P < 0.001). After adjusting for age and height, trunk lean mass was still correlated with menopausal state (P < 0.01).

CONCLUSIONS

Menopause induces lean mass loss, independent of aging and height. Trunk lean mass is more prone to decline with menopause than lean mass of other sites.

Differential impact of conventional oral or transdermal hormone replacement therapy or tibolone on body composition in postmenopausal women

OBJECTIVE

To compare the effects on body composition and body weight of tibolone vs two different sequential oral or transdermal oestrogen-progestogen hormone replacement therapies versus no therapy.

PATIENTS AND METHODS

One hundred postmenopausal women were assigned to a control group (n = 26), or randomized to 1) tibolone (TIB) 2.5 mg/day (n = 28), 2) oral oestradiol 2 mg/day (PO) plus sequential dydrogesterone 10 mg/day for 14 of 28 days per cycle (n = 26), or 3) transdermal oestradiol patch (TTS) releasing 50 micrograms/day plus oral sequential dydrogesterone 10 mg/day for 14 of 28 days per cycle (n = 20). Body composition was measured at the base-line and every 6 months for 2 years by DXA (Hologic QDR 1000 W).

RESULTS

Total body fat mass increased (P < 0.05) in controls (+3.6 +/- 1.5%) and in TTS treated (+4.7 +/- 2.2%), but not in PO (-1.2 +/- 2.4%) and TIB (-1.6 +/- 2.2%) treated subjects. This increase in total fat mass in controls and TTS treated women was mostly due to an increase in fat mass of the trunk (P < 0.05), but not legs. As a result, a redistribution of body fat to the trunk occurred in controls, TTS and TIB, but not in PO treated women (P < 0.05). Total lean body mass decreased (P < 0.02) in controls (-1.7 +/- 0.7%) and PO (-1.4 +/- 0.6%) but not in TTS (+0.3 +/- 0.8%) and TIB (+0.4 +/- 0.5%) treated subjects.

CONCLUSIONS

The menopause is associated with an increase in total body fat and a decline in lean body mass. Oral oestradiol/dydrogesterone and tibolone prevent total body fat changes, whereas transdermal oestradiol/oral dydrogesterone and tibolone prevent the lean mass changes. Furthermore, oral oestradiol/dydrogesterone prevents the shift to a central, android fat distribution.

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.

Appendicular skeletal muscle mass: effects of age, gender, and ethnicity

This study tested the hypothesis that skeletal muscle mass is reduced in elderly women and men after adjustment first for stature and body weight. The hypothesis was evaluated by estimating appendicular skeletal muscle mass with dual-energy X-ray absorptiometry in a healthy adult cohort. A second purpose was to test the hypothesis that whole body 40K counting-derived total body potassium (TBK) is a reliable indirect measure of skeletal muscle mass. The independent effects on both appendicular skeletal muscle and TBK of gender (n = 148 women and 136 men) and ethnicity (n = 152 African-Americans and 132 Caucasians) were also explored. Main findings were 1) for both appendicular skeletal muscle mass (total, leg, and arm) and TBK, age was an independent determinant after adjustment first by stepwise multiple regression for stature and weight (multiple regression model r2 = approximately 0.60); absolute decrease with greater age in men was almost double that in women; significantly larger absolute amounts were observed in men and African-Americans after adjustment first for stature, weight, and age; and >80% of within-gender or -ethnic group between-individual component variation was explained by stature, weight, age, gender, and ethnicity differences; and 2) most of between-individual TBK variation could be explained by total appendicular skeletal muscle (r2 = 0.865), whereas age, gender, and ethnicity were small but significant additional covariates (total r2 = 0.903). Our study supports the hypotheses that skeletal muscle is reduced in the elderly and that TBK provides a reasonable indirect assessment of skeletal muscle mass. These findings provide a foundation for investigating skeletal muscle mass in a wide range of health-related conditions.

Effect of sex and age on bone mass, body composition and fuel metabolism in humans

The mechanism(s) governing the gain of upper-body fat and its relationship to the decrease in bone mass with age is still unclear. Therefore, four groups of subjects matched for weight, height, and body mass index (n = 119; 60 women, 59 men), but differing in age (above and below 50 y) and sex were investigated using dual energy x-ray absorptiometry (DXA) to assess body composition (bone, lean, and fat mass as well as its distribution) and indirect calorimetry to determine resting fuel metabolism. Fat mass of trunk and arms (P < 0.01), but not legs, increased with advancing age in males, resulting in a continuous increase in the ratio of upper- to lower-body fat (r = 0.45, P < 0.001). In contrast, total fat mass remained stable in women, irrespective of menopause, but a redistribution of fat occurred with advancing age (r = 0.43, P < 0.001), resulting in a higher upper- to lower-body fat ratio (P < 0.05) in older than in younger women. Total lean soft-tissue mass of all segments of the body was greater in men than in women irrespective of age (P < 0.001), and lower in the older groups than in the younger ones irrespective of sex. In males, but not females, lean soft-tissue mass in arms and legs decreased (r = 0.57, P < 0.001), whereas the ratio of total fat to lean soft-tissue mass increased (r = 0.53, P < 0.001) with age. Bone mineral content correlated with total body fat in both groups of women and in young males (r > 0.5, P < 0.001), but not in older males. With advancing age, the proportion of lean soft-tissue mass occupied by total skeleton declined in women (n = 59, P < 0.001), but remained stable in males. Resting energy expenditure decreased with age in both sexes. Protein and carbohydrate oxidation were similar in all four groups of subjects. Total fat oxidation and fat oxidation per kilogram of lean soft-tissue mass decreased with age (r > 0.36, P < 0.01) in males, but not in females, whereas it increased with increasing fat mass in females (r > 0.32, P < 0.03), but not in males. In contrast, fat oxidation per kilogram of fat mass decreased with fat mass in males (r = 0.61, P < 0.001), but not in females. Our results suggest that aging affects body composition and fuel metabolism differently in each gender, leading to reduced fat oxidation and accumulation of upper-body fat with loss of striated muscle in men, and to an increased ratio of upper- to lower-body fat and bone loss in women, the latter depending on fat mass.

Age-related changes in body composition of healthy and osteoporotic women

OBJECTIVES

The study was carried out to assess age-related changes of body composition and to evaluate the influence of lean and fat mass in bone mineral density of healthy and osteoporotic women.

METHODS

166 healthy women in premenopause (43.2 +/- 6.7 years), 591 healthy postmenopausal women (59.9 +/- 8.1 years) and 373 women with established involutive osteoporosis (66.2 +/- 7.8 years) were evaluated: bone mineral density (BMD) and soft tissue composition (fat mass, lean mass) were measured by a total body Lunar DPX device.

RESULTS

no difference in lean mass was appreciated between the groups. Fat mass was significantly lower in premenopausal women (19.5 +/- 6.5 kg) and osteoporotic patients (18.8 +/- 5.2 kg) than in postmenopausal healthy women (21.8 +/- 5.7 kg). In premenopause weight, soft tissue mass and fat mass increased with age (P < 0.05). In postmenopause, lean mass decreased significantly in healthy women (P < 0.05). Fat mass was lower in the osteoporotics than in normals. Total BMD correlated significantly with fat and lean mass in all groups (P < 0.01). BMD/height ratio correlated significantly with fat mass (P < 0.01), not with lean mass.

CONCLUSIONS

BMD is closely related to fat mass in healthy premenopausal and postmenopausal women, and in osteoporotic patients; osteoporotic patients and healthy premenopausal women are characterized by a lower fat mass than healthy postmenopausal women; fat mass may be considered one of the determinants of bone mass also in involutive osteoporosis.

Fat or lean tissue mass: which one is the major determinant of bone mineral mass in healthy postmenopausal women?

The relative importance of fat and lean tissue mass in determining bone mineral mass among postmenopausal women was examined in this 1-year longitudinal study. Fifty postmenopausal Caucasian women entered the study; 45 of them completed a 1-year follow-up. Dual-energy X-ray absorptiometry was employed for measuring total and regional bone mineral density (BMD) and bone mineral content (BMC), fat tissue mass (FTM), lean tissue mass (LTM), and body weight. Results from linear regression analysis using the cross-sectional data (n = 50) of the study indicated that LTM explained a larger percentage of variation in bone mineral mass than did FTM. FTM and LTM were found to be moderately correlated (r = 0.55); when FTM was entered in the same predicting regression models, LTM was a significant predictor (p < 0.05) of the total and regional BMC, but not BMD. The percent FTM (and inversely %LTM) was correlated with BMD and BMC, but significant correlation was primarily found only for total body BMD (or BMC). Weight was the best predictor of total body BMD and BMC. Longitudinally (n = 45), annual changes in both FTM and weight were significantly associated with annual changes in regional BMD after adjustment for initial bone mineral values (p < 0.05). We conclude that bone mineral mass is more closely related to LTM than to FTM, while annual changes in regional BMD are more closely correlated with changes in FTM in healthy postmenopausal women. Meanwhile, increased body weight is significantly associated with increased bone mineral mass.

Relative influence of age and menopause on total and regional body composition changes in postmenopausal women

OBJECTIVE

We measured total and regional body composition to evaluate the differences in body composition associated with menopause and to determine whether the changes in fat distribution were more related to age or to menopause.

STUDY DESIGN

Two hundred five healthy white women who had never received estrogen replacement therapy were studied according to menopausal status and age. Bone mass and body composition were measured by dual x-ray absorptiometry. The proportions of android and gynoid fat were calculated in all women and differences were sought by statistical analysis.

RESULTS

Compared with premenopausal women, postmenopausal women were characterized by a significant increase in the proportion of android fat and the ratio trunk fat/leg fat, whereas the absolute amount of body fat mass did not significantly change. The different variables of android fat distribution tended to correlate better with years since menopause than with age. In multiple linear regression, years since menopause was a predictor of body fat mass and fat trunk, whereas age was not a predictor of any of the fat distribution variables.

CONCLUSIONS

This study underlines the early changes in body fat distribution with a shift of body fat toward a more central location in postmenopausal women. This change in fat distribution appears to be more related to menopause than to age and might, together with other factors, contribute to explain the increased cardiovascular risk reported in postmenopausal women.

Relationship between body composition and bone mass in women

Increasing body weight is associated both with higher bone mass and with lower rates of bone loss. Whether the effects of body weight are mediated by lean body mass (LBM) or fat body mass (FBM) is, however, uncertain because different studies have used different measures of bone mass and arrived at contradictory conclusions. The parameter actually measured is bone mineral content (BMC). Bone mineral density (BMD), bone mineral apparent density (BMAD), and the BMD/height attempt to "correct" BMC for differences in bone or body size, but these corrections may bias the analysis of the effects of body composition on the skeleton. To resolve this issue, we measured BMC at the total body, lumbar spine, proximal femur, and forearm using dual energy X-ray absorptiometry (DXA) in a population-based sample including 138 premenopausal women (age range 21-54 years, mean 35 years) and 213 postmenopausal women (age range 34-94 years, mean 68 years). BMD, BMAD, and BMD/ height were also calculated for each site. LBM and FBM were determined from the DXA whole body scan. In a multivariate analysis that included age and height, both LBM and FBM predicted total body BMC in pre- and postmenopausal women (p < 0.002 for LBM and FBM in both groups). LBM had a dominant effect on spine and forearm BMC in both groups (p < 0.004) and hip BMC in premenopausal women (p < 0.001), whereas both LBM and FBM predicted hip BMC in postmenopausal women (p < 0.001). However, as BMC was adjusted for bone or body size using BMD, BMAD, or BMD/height, FBM tended to become more important than LBM in the analysis. This was, in part, due to the fact that each of the correction factors in the BMD and BMAD calculations, as well as height, were highly correlated with LBM (r = 0.57 and 0.52 for height versus LBM in pre- and postmenopausal women, respectively [p < 0.001]), and weakly or not at all with FBM (r = 0.08 and 0.11, respectively). Therefore, dividing BMC by these correction factors tended to bias the analysis against potential effects of LBM on bone mass. Thus, the relationship between body composition and bone mass is critically dependent on which bone mass parameter is used in the analysis. Both LBM and FBM have important effects on bone mass, depending on the bone mass parameter used, the skeletal site measured, and menopausal status.

Do genetic factors explain associations between muscle strength, lean mass, and bone density? A twin study

Are the associations between muscle strength, lean mass, and bone mineral density (BMD) genetically determined? Based on within-pair differences in 56 monozygotic (MZ) and 56 dizygotic (DZ) female twin pairs, mean age 45 yr (range 24-67), BMD was associated with lean mass, independent of fat mass and height (P < 0.05). A 10% increment in femoral neck (FN) BMD was associated with a 15% increment in lean mass (approximately 6 kg). BMD was associated with muscle strength (measured in 35 pairs) before, but not after, adjusting for lean mass. Based on age-adjusted cross-sectional analyses, same-trait correlations (+/- SE) in MZ pairs were double those in DZ pairs: FN BMD (0.62 +/- 0.08, 0.33 +/- 0.12) and lean mass (0.87 +/- 0.03, 0.30 +/- 0.11; all P < 0.001), consistent with a genetic hypothesis. The cross-trait correlation (r) between lean mass and FN BMD in the same individual was 0.43 +/- 0.06. The cross-trait cross-twin correlation between lean mass in one twin and FN BMD in the other was 0.31 +/- 0.07 in MZ pairs, approximately 75% of the cross-trait correlation (r) and 0.19 +/- 0.09 in DZ paris (P < 0.001). After adjusting for height and fat mass, the MZ and DZ cross-trait cross-twin correlations were no different (0.16 +/- 0.08 and 0.13 +/- 0.09, respectively). Therefore, genetic factors account for 60-80% of the individual variances of both FN BMD and lean mass, and > 50% of their covariance. The association between greater muscle mass and greater BMD is likely to be determined by genes regulating size.

Age- and menopause-associated variations in body composition and fat distribution in healthy women as measured by dual-energy X-ray absorptiometry

To assess the variation with age and menopause, 407 healthy normal women aged 18 to 75 years had body composition and fat distribution measured by dual-energy x-ray absorptiometry (DEXA). The mean +/- SD are given for different age decades. Postmenopausal women had significantly more fat, a more central fat distribution, and less lean tissue mass (LTM) than premenopausal women. In premenopausal and postmenopausal women, age only correlated with the abdominal to total-body fat tissue ratio (r approximately .24, P < .05), whereas the years since onset of menopause correlated with fat tissue mass (FTM), fat%, abdominal fat%, and the abdominal to total-body fat tissue ratio (r approximately .2, P < .05). To assess the independent impact of age, menopausal status, and years since menopause, multiple linear regressions were performed. FTM, fat%, and abdominal fat% were significantly related to menopausal status and years since menopause independently of age. The abdominal to total-body fat tissue ratio was statistically significantly related to age, but tended also to be independently related to years since menopause. LTM was statistically significantly related to menopausal status independently of age and years since menopause. In summary, we suggest that in healthy women total-body and abdominal fat may increase and LTM may decrease in the years after menopause, primarily in the perimenopausal years, without significant changes before menopause.

The influence of menopause and hormonal replacement therapy on body cell mass and body fat mass

OBJECTIVE

Our purpose was to determine the efficacy of dietary calcium augmentation in the prevention of early postmenopausal bone density loss in comparison with hormonal replacement therapy and placebo.

STUDY DESIGN

A three-arm parallel randomized trial comparing the influence of placebo, dietary calcium augmentation, and estrogen-progesterone-calcium in 118 women who were within 6 years of menopause was conducted. Dual photon absorptiometry was performed annually to measure lean and fat mass. In addition, the ratio of fat in the trunk/extremities was measured.

RESULTS

Body weight increased in each group. The increase was statistically significant in the hormone replacement group (0.8 kg/year). The percent of body fat increased in each group from baseline measurements, with the greatest increase in the hormonal replacement group. There was a decline in the extremity/trunk ratio in the hormonal replacement group as a result of a relatively greater increase in the trunk fat mass. There was a rapid rate of loss in lean body mass that was equal among groups.

CONCLUSIONS

Menopause is associated with a gain in fat mass and a loss of lean body mass, but these changes in body composition are not prevented by hormone replacement therapy.

Gymnasts exhibit higher bone mass than runners despite similar prevalence of amenorrhea and oligomenorrhea

Female athletes exhibit a higher prevalence of exercise-associated amenorrhea and oligomenorrhea compared with nonathletic women, and both conditions are related to reduced bone mineral density (BMD), particularly at the spine. This study investigated bone mass and oligomenorrhea and amenorrhea in two groups of competitive female athletes with different skeletal loading patterns: gymnasts and runners. Bone mineral density (g/cm2) of the femoral neck, lumbar spine (L2-4), and whole body was assessed by dual energy X-ray absorptiometry (QDR-1000/W, Hologic Inc., Waltham, MA) in collegiate gymnasts (n = 21) and runners (n = 20), and nonathletic college women (n = 19). The runners and gymnasts had similar values for percent body fat (14.7 +/- 2.2% and 15.6 +/- 2.9%, respectively), which were lower (p < 0.001) than controls (22.3 +/- 3.0%). Lean body mass (LBM) did not differ among the groups, but when adjusted for body surface area, gymnasts had a higher LBM/height2 (p = 0.0001) compared with runners and controls. Muscle strength was significantly greater (p < 0.05) in gymnasts for quadriceps, biceps, and hip adductor force, compared with runners and controls. Gymnasts had a significantly later menarche age (16.2 +/- 1.7 years) compared with runners (14.4 +/- 1.7 years) and controls (13.0 +/- 1.2 years). The prevalence of oligo- and amenorrhea was 47% for gymnasts (6 amenorrheic, 4 oligomenorrheic), 30% for runners (3 amenorrheic, 3 oligomenorrheic), and 0% for controls. Furthermore, athletic groups had similar menstrual histories given the higher proportion of gymnasts who had experienced primary amenorrhea. When evaluated since menarche, however, runners had somewhat longer histories due to an earlier age at menarche and slightly older ages. Dietary calcium intake did not differ among groups, although mean values were below the RDA of 1200 mg/day. By athletic group, BMD at any site did not differ among women with amenorrhea versus oligomenorrhea versus eumenorrhea, although there was a trend for the regularly menstruating athletes in both groups to have slightly higher values. Lumbar spine BMD was lower (p = 0.0001) in runners (0.98 +/- 0.11 g/cm2) compared with both gymnasts and controls (1.17 +/- 0.13 and 1.11 +/- 0.11 g/cm2, respectively). Femoral neck BMD differed among all groups (p = 0.0001): gymnasts = 1.09 +/- 0.12 g/cm2 > controls = 0.97 +/- 0.10 g/cm2 > runners = 0.88 +/- 0.11 g/cm2. Whole body BMD was lower (p < 0.01) in runners (1.04 +/- 0.06 g/cm2) compared with gymnasts and controls (1.11 +/- 0.08 and 1.09 +/- 0.06 g/cm2, respectively).(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of resistive and balance exercises on isokinetic strength in older persons

OBJECTIVE

To determine the safety and efficacy of 3 months of resistive training of multiple lower extremity muscle groups compared with balance training in persons over 75 years.

DESIGN

Randomized 3-month clinical trial. Subjects (n = 110, mean age 80) were randomized to 4 groups in a 2 x 2 design (control, resistive, balance, combined resistive/balance).

INTERVENTIONS

Resistive training involved knee extension and flexion, hip abduction and extension, and plantar and dorsiflexion using simple resistive machines and sandbags. Balance training consisted of exercises to improve postural control. The control group attended 5 health-related discussion sessions.

MEASUREMENTS

Summed isokinetic moments (N m) of 8 leg movements: hip, knee and ankle flexion/extension, and hip abduction/adduction. Secondary outcomes were gait velocity and chair rise time.

MAIN RESULTS

Summed peak moment increased in both resistive exercise-trained groups (13% increase in the resistive group and 21% in the combined training group, P < 0.001). The effect of resistance training was significant (MANOVA F = 21.1, P < 0.001), but balance training did not improve strength, and there was no interaction (positive or negative) between balance and resistive training. Maximal gait velocity and chair rise time did not improve. Eleven subjects (20%) had musculoskeletal complaints related to resistive training, but all were able to complete the program with modifications.

CONCLUSION

Resistive training using simple equipment is an effective and acceptable method to increase overall leg strength in older persons. Resistive or balance training did not improve maximal gait velocity or chair rise time in this sample of relatively healthy older persons.

Quantifying the effect of hand preference on upper limb bone mineral and soft tissue composition in young and elderly women by dual-energy X-ray absorptiometry

The purpose of this study was to quantify the effect that hand preference has on upper limb bone mineral and soft tissue composition in healthy young and elderly women. Bone mineral content (BMC) in grams, bone mineral density (BMD) in g cm-2, fat-free soft tissue (FFST) in grams, fat tissue (g), and percent fat were determined by dual-energy X-ray absorptiometry (DXA) for dominant and non-dominant upper limbs as well as total body fat (%) in 25 young (26.6 +/- 4.3 years, mean +/- SD) and 35 elderly women (68.4 +/- 2.9 years). For both groups, the dominant upper limb had a greater BMC (P < 0.001), BMD (young, P < 0.001; elderly, P < 0.05), and FFST mass (P < 0.001), and a lower percent fat (young, P < 0.01; elderly, P < 0.05) than the non-dominant limb; however, there was no difference between limbs for total fat mass. BMC, BMD, and FFST in the dominant limb of young women were 7.1%, 1.8%, and 5.1% greater than the non-dominant limb, while for older women the differences were 5.3%, 1.0%, and 4.2%. Relative fat of the dominant limb was 3.0% and 1.3% less than the non-dominant limb for young and older women, respectively. Age did not affect the percent bone mineral or soft tissue difference. A higher bone mineral and FFST mass in the dominant limb is expected due to the greater activity demands placed upon these tissues. However, a larger bone and FFST mass increases the total mass of the dominant limb, resulting in a dilution of the fat tissue mass and hence a reduced fat percent for the limb. This study indicates that hand preference affects the tissue composition of the upper limb in both young and elderly women, resulting in an increased bone mineral and FFST mass with no change in absolute fat mass. Hand preference should be taken into account when upper limb bone mineral and/or soft tissue composition is assessed.

Menopausal changes in body composition and energy expenditure

Adult American women as a group tend to gain weight with age, and many women report that their weight gain started around the time of their menopause. Moreover, as women age, there are changes in body composition that include losses in bone mineral and body cell mass, and increases in total body fat, visceral fat, and extracellular fluid. It appears as if these body composition changes begin or accelerate during the menopausal years. The importance of weight gain and changes in body composition are their associations with an increased risk of developing some malignancies, cardiovascular disease, osteoporosis, and several other clinical conditions. This overview describes selected studies of menopause and aging-associated weight gain, changes in body composition, and alterations of energy expenditure in women. Gaps in the present understanding of these changes are highlighted, and an emphasis is placed on new research methodologies for investigating body composition and energy expenditure in vivo. A concluding section of the report summarizes areas in need of future investigation.

The effect of obesity on postmenopausal bone loss and the risk of osteoporosis

There are many data indicating that osteoporotic fractures, and particularly hip fractures, are less frequent in obese subjects. Overweight and obese women have a higher bone mass after menopause than women of the same age who are not overweight, and thus in all probability have a slower bone loss. This protective effect appears to be related both to mechanical factors and to estrogen synthesis in adipose tissue.

Importance of bone resorption in the determination of bone density in women more than 10 years past the menopause

There is general agreement that bone density falls with age and is higher in heavy people than light people. We have studied a variety of potential correlates of vertebral, ankle, and hip bone density to evaluate other potential influences on the skeleton. We recruited 196 healthy women who were more than 10 years past the menopause and collected a diet and activity record, a 24 h urine, and a fasting blood and urine specimen. These blood and urine samples were analyzed for factors related to calcium homeostasis. We then measured bone density at lumbar vertebrae 1-4 and the hip and the ankle bone density of the nondominant leg. Correlations between vertebral, hip, and ankle bone density and other measured variables were explored using the statistical package SPSS PC. At the vertebral site, in addition to correlations with age and body mass index (BMI), a negative correlation with a measure of bone resorption, the hydroxyproline creatinine ratio (OHPCR), was noted. At the ankle site, in addition to correlation with age, BMI, and OHPCR, a positive correlation with activity and a negative correlation with serum calcitriol were noted. At the hip site, as well as age, BMI, and OHPCR, significant correlations with GFR and dietary calcium intake were noted. These data suggest that even in women 10 years past the menopause bone resorption has a significant effect on bone density, that renal function may account for some of the variance in bone density at the hip, and that activity effects are more marked at sites of greater loading, namely the ankle.

Body composition and bone mass in post-menopausal women

OBJECTIVE

We aimed to assess total body composition and to study the interrelationships between fat and lean tissue mass with total and regional bone mass in healthy British post-menopausal women.

DESIGN AND PATIENTS

Total body composition and regional bone mass were measured in 97 healthy post-menopausal women recruited from the general community. The mean age was 57.9 years, range 49-65.

MEASUREMENTS

Total body composition (fat, lean tissue and bone mineral) and regional bone density in the lumbar spine and femur were measured by dual energy X-ray absorptiometry on a Lunar DPX.

RESULTS

Significant negative correlations with age were found for total body bone mineral density (r = -0.200, P = 0.049), and lumbar spine bone mineral density (r = -0.28, P = 0.006); the calculated rate of bone loss from these two sites was 0.33 and 0.7% per annum respectively. Fat tissue mass showed a positive correlation with age (r = 0.22, P = 0.03). High correlations were observed between total body and regional bone mineral density (r = 0.755-0.829, P < 0.001). After adjustment for age and lean mass, statistically significant correlations were seen between fat tissue mass and all bone mass measurements (P < 0.01-0.001), the strongest correlations being found for total body bone mineral content and density (r = 0.477 and 0.488 respectively). Lean tissue mass showed a strong correlation with total body bone mineral content (r = 0.580, P < 0.001), after adjustment for age and fat mass; it was less strongly correlated with other bone mass measurements than fat mass, showing only weak correlations with total body, trochanteric and lumbar spine bone mineral density (r = 0.228-0.246, P < 0.05). Age-adjusted body weight showed stronger correlations with total and regional bone mass than did either body mass index or height.

CONCLUSIONS

Both fat and lean tissue mass are related to total and regional bone mass in post-menopausal women, the relationship being strongest for fat mass. Body weight shows stronger correlations with bone mass than either height or body mass index. In view of the direction and magnitude of changes in fat, lean tissue and bone mineral after the menopause, adiposity and muscularity are more likely to be determinants of peak bone mass than of the rate of post-menopausal bone loss.