Estrogen replacement and skeletal muscle: mechanisms and population health

Prognostic value of body composition measures in breast cancer patients treated with chemotherapy

Breast cancer remains a significant public health issue, often resulting in severe side effects such as neutropenia, highlighting the need for reliable predictors of clinical outcomes. This study aimed to evaluate the predictive value of body composition measures for mortality, recurrence, and chemotherapy-induced neutropenia in patients with breast cancer following surgery and chemotherapy. We retrospectively analyzed 85 breast cancer patients who underwent surgery and chemotherapy between 2006 and 2016. Body composition was assessed using computed tomography (CT) or positron emission tomography (PET) at diagnosis and three years and five years post-diagnosis. Metrics included skeletal muscle area (SMA), skeletal muscle index (SMI), subcutaneous adipose tissue area (SAT), and visceral adipose tissue area (VAT). Longitudinal analysis revealed a decrease in muscle mass (P < 0.001 for both SMA and SMI) and nonsignificant changes in fat mass (P = 0.449 for SAT and P = 0.798 for VAT). A lower SMI at diagnosis was significantly associated with increased mortality (P = 0.019) and a higher incidence of grade 4 neutropenia (P = 0.008). There was no significant association between SMI at diagnosis and recurrence (P = 0.691). No associations were found between body composition measurements during the follow-up period and the clinical outcomes. Lower skeletal muscle mass at diagnosis is strongly associated with higher mortality and chemotherapy-induced complications in patients with breast cancer, highlighting the potential of readily available imaging techniques as valuable predictors of clinical outcomes.

Evaluating the effects of hormone therapy termination on skeletal muscle and physical independence in postmenopausal women

OBJECTIVE

In women, the age-related decline in skeletal muscle structure and function is accelerated after menopause, which implicates the role of decreased circulating estrogen levels. Indeed, boosting estrogen, by means of postmenopausal hormone therapy (HT), generally proves beneficial to skeletal muscle. The evidence regarding whether these benefits persist even after cessation of HT is limited, nor is it clear how physical behavior (PB) impacts on benefits. Hence, this exploratory study focused on the interplay between HT administration/cessation, PB and in vivo skeletal muscle structure and function.

METHODS

Fifty healthy women (≥60 y) were included; 19 had an HT administration history (≥9 mo, with now ~8-y hiatus in treatment) and 31 no such history. On seven continuous days, PB data were collected using triaxial accelerometry and analyzed using compositional data analysis. Gastrocnemius medialis muscle volume, architecture, and function were determined using ultrasonography, electromyography, dual x-ray absorptiometry, and dynamometry. Current serum estradiol levels were measured using ELISA.

RESULTS

Only fascicle length and duration of HT administration were positively associated. With respect to PB levels, we found a pattern suggesting greater vitality (higher physical activity and lower sedentarism) in previous HT users, compared with nonusers, despite the two groups currently no longer exhibiting significantly different levels of circulating estradiol.

CONCLUSIONS

After an 8-year hiatus in treatment, HT provides limited advantages in gastrocnemius medialis muscle properties. Interestingly, it perhaps enhances vitality despite prolonged cessation, which in the longer term would facilitate greater physical independence, especially considering the association of sedentary behavior with greater frailty.

Effects of chemically induced ovarian failure on single muscle fiber contractility in a mouse model of menopause

OBJECTIVE

Menopause is associated with impaired skeletal muscle contractile function. The temporal and mechanistic bases of this dysfunction are unknown. Using a mouse model of menopause, we identified how gradual ovarian failure affects single muscle fiber contractility.

STUDY DESIGN

Ovarian failure was chemically induced over 120 days, representing the perimenopausal transition. Mice were sacrificed and soleus and extensor digitorum longus muscles were dissected and chemically permeabilized for single fiber mechanical testing.

MAIN OUTCOME MEASURES

Muscle fiber contractility was assessed via force, rate of force redevelopment, instantaneous stiffness, and calcium sensitivity.

RESULTS

Peak force and cross-sectional area of the soleus were, respectively, ~33 % and ~24 % greater following ovarian failure compared with controls (p < 0.05) with no differences in force produced by the extensor digitorum longus across groups (p > 0.05). Upon normalizing force to cross-sectional area there were no differences across groups (p > 0.05). Following ovarian failure, rate of force redevelopment of single fibers from the soleus was ~33 % faster compared with controls. There was no shift in the midpoint of the force‑calcium curve between groups or muscles (p > 0.05). However, following ovarian failure, Type I fibers from the soleus had a higher calcium sensitivity between pCa values of 4.5 and 6.2 compared with controls (p < 0.05), with no differences for Type II fibers or the extensor digitorum longus (p > 0.05).

CONCLUSIONS

In our model of menopause, alterations to muscle contractility were less evident than in ovariectomized models. This divergence across models highlights the importance of better approximating the natural trajectory of menopause during and after the transitional phase of ovarian failure on neuromuscular function.

Passive exercise is an effective alternative to HRT for restoring OVX induced mitochondrial dysfunction in skeletal muscle

Background

Postmenopausal women are more prone to develop muscle weakness, which is strongly associated with impairment of mitochondrial function in skeletal muscle. This study aimed to examine the impact of a passive exercise modality, whole-body vibration training (WBVT), on muscle mitochondrial function in ovariectomized (OVX) mice, in comparison with 17β-estradiol (E2) replacement.

Methods

Female C57BL/6J mice were assigned to four groups: sham operation control group (Sham), ovariectomized group (OVX), OVX with E2 supplement group (OVX+E), and OVX with WBVT group (OVX+W). The estrous cycle, body weight, body composition, and muscle strength of the mice were monitored after the operation. Serum E2 level was assessed by enzyme-linked immunosorbent assay (ELISA). The ATP levels were determined using a luciferase-catalyzed bioluminescence assay. The activity of mitochondrial respiration chain complexes was evaluated using high-resolution respirometry (O2K). Expression levels of oxidative phosphorylation (OXPHOS), peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α), and mitochondrial transcription factor A (TFAM) were detected using western blotting.

Results

We observed decreased muscle strength and impaired mitochondrial function in the skeletal muscle of OVX mice. The vibration training alleviated these impairments as much as the E2 supplement. In addition, the vibration training was superior to the ovariectomy and the estradiol replacement regarding the protein expression of PGC-1α and TFAM.

Conclusion

WBVT improves the OVX-induced decline in muscle strength and impairment of mitochondrial function in the skeletal muscle. This passive exercise strategy may be useful as an alternative to E2 replacement for preventing menopausal muscular weakness. Further studies are needed to understand the effects of WBVT on various physiological systems, and precautions should be taken when implementing it in patient treatment.

The Impact of the Physical Activity Level on Sarcopenic Obesity in Community-Dwelling Older Adults

Previous studies have reported that low levels of physical activity result in sarcopenic obesity (SO). However, the effects of specific intensities of physical activity on SO and the optimal amount of physical activity for lowering the prevalence of SO have not been well studied. This study aimed to identify the effects of physical activity levels and intensity on SO and the optimal amount of physical activity related to a lower prevalence of SO. This cross-sectional study used data from the nationwide Korean Frailty and Aging Cohort Study (KFACS), which included 2071 older adults (1030 men, 1041 women). SO was defined according to the criteria of the European Society for Clinical Nutrition Metabolism (ESPEN) and the European Association for the Study of Obesity (EASO). Multivariate logistic regression analysis was performed to investigate the association between the physical activity level and SO. The high activity group had a significantly lower prevalence of SO than the non-high activity (low and moderate activity) group. On the other hand, moderate-intensity physical activity was associated with a lower prevalence of SO. A total physical activity energy expenditure of > 3032 kcal/week (433 kcal/day) for men and 2730 kcal/week (390 kcal/day) for women was associated with a reduced prevalence of SO. The high physical activity and total physical energy expenditure described above may be beneficial for reducing the prevalence of SO.

Biological sex divergence in transcriptomic profiles during the onset of hindlimb unloading-induced atrophy

Disuse-induced muscle atrophy is a common clinical problem observed mainly in older adults, intensive care units patients, or astronauts. Previous studies presented biological sex divergence in progression of disuse-induced atrophy along with differential changes in molecular mechanisms possibly underlying muscle atrophy. The aim of this study was to perform transcriptomic profiling of male and female mice during the onset and progression of unloading disuse-induced atrophy. Male and female mice underwent hindlimb unloading (HU) for 24, 48, 72, and 168 h (n = 8/group). Muscles were weighed for each cohort and gastrocnemius was used for RNA-sequencing analysis. Females exhibited muscle loss as early as 24 h of HU, whereas males after 168 h of HU. In males, pathways related to proteasome degradation were upregulated throughout 168 h of HU, whereas in females these pathways were upregulated up to 72 h of HU. Lcn2, a gene contributing to regulation of myogenesis, was upregulated by 6.46- to 19.86-fold across all time points in females only. A reverse expression of Fosb, a gene related to muscle degeneration, was observed between males (4.27-fold up) and females (4.57-fold down) at 24-h HU. Mitochondrial pathways related to tricarboxylic acid (TCA) cycle were highly downregulated at 168 h of HU in males, whereas in females this downregulation was less pronounced. Collagen-related pathways were consistently downregulated throughout 168 h of HU only in females, suggesting a potential biological sex-specific protective mechanism against disuse-induced fibrosis. In conclusion, females may have protection against HU-induced skeletal muscle mitochondrial degeneration and fibrosis through transcriptional mechanisms, although they may be more vulnerable to HU-induced muscle wasting compared with males.NEW & NOTEWORTHY Herein, we have assessed the transcriptomic response across biological sexes during the onset and progression of unloading disuse-induced atrophy in mice. We have demonstrated an inverse expression of Fosb between males and females, as well as differentially timed patterns of expressing atrophy-related pathways between sexes that are concomitant to the accelerated atrophy in females. We also identified in females signs of mechanisms to combat disuse-induced mitochondrial degeneration and fibrosis.

Verification of a Three-day Hospitalization Protocol for Chronic Subdural Hematoma Surgery

Chronic subdural hematoma (CSH) is predominantly a disease of the elderly. Aging societies in advanced countries are seeing the number of CSH cases increasing. We applied a three-day hospitalization protocol for CSH surgery to reduce healthcare costs and more efficiently manage hospital beds. We investigated the clinical factors that influenced prolonged hospitalization. From January 2015 to December 2020, we performed irrigation, evacuation, and drainage of CSH cases in 221 consecutive patients. The χ2 test and logistic regression analysis were conducted to detect clinical factors influencing prolonged hospitalization. A p-value below 0.05 was considered statistically significant. Applying a three-day hospitalization protocol showed no adverse outcomes. Fifty-two (24%) of 221 patients experienced prolonged hospitalization. The χ2 test showed that female gender, atrial fibrillation, alcohol abuse, preoperative consciousness level, verbal function disturbance, and perioperative activities of daily living were significantly related to prolonged hospitalization. Female gender, atrial fibrillation, and alcohol abuse were significant factors in the logistic regression analysis. A three-day hospitalization protocol for CSH is suitable for patient care; however, particular attention needs to be focused on the female gender, atrial fibrillation, and alcohol abuse, all three of which prolong hospitalization.

Effect of Different Load Intensity Transition Schemes on Muscular Strength and Physical Performance in Postmenopausal Women

PURPOSE

In postmenopausal women, optimizing muscular strength and physical performance through proper resistance training (RT) is crucial in achieving optimal functional reserve later in life. This study aimed to compare if a higher-load-to-lower-load (HL-to-LL) scheme is more effective than a lower-load-to-higher-load (LL-to-HL) scheme on muscular strength and physical performance in postmenopausal women after 12 and 24 wk of RT.

METHODS

Twenty-four postmenopausal women were randomized into two groups: LL-to-HL ( n = 12, 27-31 repetitions maximum (RM) in the first 12 wk, and 8-12RM in the last 12 wk) or HL-to-LL ( n = 12, 8-12RM during the first 12 wk, and 27-31RM in the last 12 wk). Muscular dynamic (1RM test) and isometric strength (MIVC) and functional tests (sit-to-stand power, 400-m walking, and 6-min walking) were analyzed at baseline, after 12 and 24 wk.

RESULTS

Different load intensity transition schemes resulted in enhancements ( P < 0.05) in dynamic (45° leg press: LL-to-HL = 21.98% vs HL-to-LL = 16.07%; leg extension: LL-to-HL = 23.25% vs HL-to-LL = 16.28%; leg curl: LL-to-HL = 23.89% vs HL-to-LL = 13.34%) and isometric strength (LL-to-HL = 14.63% vs HL-to-LL = 19.42%), sit-to-stand power (LL-to-HL = 7.32% vs HL-to-LL = 0%), and walking speed (400-m test: LL-to-HL = 3.30% vs HL-to-LL = 5.52%; 6-min test: LL-to-HL = 4.44% vs HL-to-LL = 5.55%) after 24 wk of RT, without differences between groups ( P > 0.05). However, only the HL increased the dynamic strength in 45° leg press and leg extension and sit-to-stand power. Moreover, walking speed changes were more strongly correlated with the changes in MIVC ( P < 0.05).

CONCLUSIONS

Our results indicate that both load intensity transition schemes produce similar improvements in muscular strength and physical performance in postmenopausal women after 24 wk of RT. However, the HL was more effective in increasing 45° leg press and leg extension strength, as well as power (mainly when performed after the LL), whereas having little effect on leg curl strength, isometric strength, and walking speed. Our findings suggest that although an HL makes a muscle isotonically stronger, it may have limited impact on isometric strength and walking speed in postmenopausal women.

The Participation of Trans Women in Competitive Fencing and Implications on Fairness: A Physiological Perspective Narrative Review

Debate has surrounded whether the participation of trans women in female sporting categories is fair, specifically the retained male physiological advantage due to increased testosterone compared to cisgender females. Recently, individual sporting organisations have been investigating and assessing policies regarding trans women athlete participation in female categories, resulting in several banning participation. This review aims to discuss the scientific evidence and provide appropriate guidance for the inclusion of trans women in elite competitive female fencing categories. Fencing is an intermittent sport, where competitions can span 1 to 3 days. The lunge is the most common movement used to attack opponents, where a successful hit relies on the speed of the action. Male puberty induced increased circulating testosterone promotes a greater stature, cardiovascular function, muscle mass, and strength compared to cisgender females, culminating in a ~12-40% sport performance advantage. Elite cisgender male fencers perform significantly higher, ~17-30%, jump heights and leg power measures compared to elite cisgender female fencers, resulting in faster lunges. Trans women receiving androgen-suppression therapy for 12 months showed significant reductions in strength, lean body mass, and muscle surface area, but even after 36 months, the measurements of these three indices remained above those for cisgender females. Previous male muscle mass and strength can be retained through continuation of resistance training. The literature reviewed shows that there is a retained physiological advantage for trans women who have undergone male puberty when participating in the elite competitive female fencing category. A proposed solution of an open or third gender category for elite fencing competition promotes fair competition, while allowing trans women to compete in their chosen sport.

Low-intensity pulsed ultrasound and parathyroid hormone improve muscle atrophy in estrogen deficiency mice

Due to aging and long-term estrogen deficiency, postmenopausal women suffer muscle atrophy (MA), which is characterized by decreased muscle mass and muscle quality. Low-intensity pulsed ultrasound (LIPUS) is an acoustic wave inducing biological effects mainly by the mechanical stimulation and used as a non-invasive physical therapy for muscle repair. Parathyroid hormone (PTH) is an 84-amino-acid polypeptide, and its bioactive fragment [PTH (1-34)] has potential application in the treatment of MA. We speculate that the combination of physical therapy (i.e., the LIPUS) and regulatory hormone (i.e., the PTH) would be more effective in the treatment of MA. The objective of this study was to evaluate the individual and combined effects of LIPUS and PTH therapy on MA in estrogen deficiency mice. Seventy 8-week-old female C57BL/6J mice were used in this study and the MA model was induced by an intraperitoneal injection of 4-vinylcyclohexene diepoxide (VCD) for 20 consecutive days. The VCD-induced MA mice were randomly divided into MA, LIPUS, PTH and LIPUS + PTH (Combined) groups (n = 10/group). In the LIPUS group, the mice were treated by LIPUS in bilateral quadriceps muscles for 20 min, five times a week for 6 weeks. In the PTH group, the mice received subcutaneous injection of PTH (1-34) (80 ug/kg/d) five times a week, for 6 weeks. In the Combined group, the PTH was administrated 30 min before each LIPUS session. Hematoxylin-eosin (H&E) staining, serum biochemical analysis and quantitative real-time polymerase chain reaction (qRT-PCR) were applied to evaluate the therapeutic effects of related treatments. The results showed that the MA mice had a disordered estrus cycle, significantly decreased muscle mass and myofibers cross-sectional area (CSA). After treatments, LIPUS, PTH and Combined groups had a significantly increased CSA, compared with the MA mice without treatment. In addition, Combined group had a significantly increased mRNA expression of Pax7, MyoD and MyoG, compared with LIPUS and PTH monotherapy groups. Our findings indicated that the combination of LIPUS and PTH treatment improves muscle regeneration ability, which might have potential for treating MA in postmenopausal women.

The unconditioned fear response in dystrophin-deficient mice is associated with adrenal and vascular function

Loss of function mutations in the gene encoding dystrophin elicits a hypersensitive fear response in mice and humans. In the dystrophin-deficient mdx mouse, this behaviour is partially protected by oestrogen, but the mechanistic basis for this protection is unknown. Here, we show that female mdx mice remain normotensive during restraint stress compared to a hypotensive and hypertensive response in male mdx and male/female wildtype mice, respectively. Partial dystrophin expression in female mdx mice (heterozygous) also elicited a hypertensive response. Ovariectomized (OVX) female mdx mice were used to explain the normotensive response to stress. OVX lowered skeletal muscle mass and lowered the adrenal mass and zona glomerulosa area (aldosterone synthesis) in female mdx mice. During a restraint stress, OVX dampened aldosterone synthesis and lowered the corticosterone:11-dehydrocorticosterone. All OVX-induced changes were restored with replacement of oestradiol, except that oestradiol lowered the zona fasciculata area of the adrenal gland, dampened corticosterone synthesis but increased cortisol synthesis. These data suggest that oestrogen partially attenuates the unconditioned fear response in mdx mice via adrenal and vascular function. It also suggests that partial dystrophin restoration in a dystrophin-deficient vertebrate is an effective approach to develop an appropriate hypertensive response to stress.

Menopause hormone therapy and sarcodynapenia: the Canadian Longitudinal Study on Aging

OBJECTIVE

To study the association between menopause hormone therapy (MHT) and sarcodynapenia in women from the Canadian Longitudinal Study on Aging.

METHODS

We conducted a cross-sectional study of 10,834 eligible postmenopausal women. The exposure was prior or current use of MHT (never, ever). Sarcopenia was defined as an appendicular lean mass less than 5.72 kg/m 2 using dual-energy X-ray absorptiometry, and dynapenia as a grip strength less than 20.4 kg. Sarcodynapenia was defined as the concomitant presence of sarcopenia and dynapenia. Poisson regression analysis produced prevalence ratios (PR) for the associations between MHT use and sarcodynapenia adjusted for age at interview, education, study site, smoking, diabetes, hypertension, and body mass index. Additional analyses were conducted according to duration of MHT (5 years or less, more than 5 years), age categories (45-64 years, 65 years or older), and physical activity level as per the Physical Activity Scale for the Elderly score (less active, more active).

RESULTS

Menopause hormone therapy was not associated with sarcodynapenia (PR, 1.10; 95% CI, 0.89-1.35). When subdivided by years of use and physical activity, relative to no MHT use, MHT use for 5 years or less was associated with a higher prevalence of sarcodynapenia among less active women (PR, 1.57; 95% CI, 1.11-2.21) and with a lower prevalence among those more active (PR, 0.60; 95% CI, 0.39-0.92). The use of MHT for more than 5 years was not associated with sarcodynapenia.

CONCLUSIONS

Menopause hormone therapy for 5 years or less is associated with a lower prevalence of sarcodynapenia among physically active women and with a higher prevalence of sarcodynapenia in those less active. Strategies to promote an active lifestyle in all postmenopausal women, including MHT users, are needed to attain benefits for musculoskeletal health.

Intramuscular sex steroid hormones are reduced after resistance training in postmenopausal women, but not affected by estrogen therapy

Animal and human studies suggest that low concentrations of circulating sex steroid hormones play a critical role in the accelerated loss of muscle mass and strength after menopause. The skeletal muscle can produce sex steroid hormones locally, however, their presence and regulation remain mostly elusive. The purpose of this study was to examine sex steroid hormone concentrations in skeletal muscle biopsies from postmenopausal women before and after 12-weeks of resistance training with (n = 15) or without (n = 16) estrogen therapy, and after acute exercise. Furthermore, associations between circulating sex hormones, intramuscular sex steroid hormones and muscle parameters related to muscle strength, mass and quality were elucidated. Blood and muscle samples, body composition (DXA-scan), muscle size (MR), and muscle strength measures were determined before and after the intervention. An additional blood and muscle sample was collected after the last resistance exercise bout. The results demonstrated reduced intramuscular estradiol, testosterone and dehydroepiandrosterone (DHEA) concentrations after resistance training irrespective of estrogen therapy. Acute exercise had no effect on intramuscular sex hormone levels. Low circulating levels of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) associated with high muscle mass at baseline, and a decline in circulating FSH after the intervention associated with a greater gain in muscle cross-sectional area in response to the resistance training. In conclusion, intramuscular estradiol, testosterone and DHEA were reduced by resistance training and unaffected by changes in circulating estrogen levels induced by estrogen therapy. Serum FSH and LH were superior predictors of muscle mass compared to other circulating and intramuscular sex steroid hormones.

Estrogen regulation of myokines that enhance osteoclast differentiation and activity

Osteoporosis and sarcopenia are maladies of aging that negatively affect more women than men. In recent years, it has become apparent that bone and muscle are coupled not only mechanically as muscle pulls on bone, but also at a higher level with myokines, biochemical and molecular signaling occurring between cells of the two tissues. However, how estrogen deficiency in females impacts the chemical crosstalk between bone and muscle cells is not understood. We hypothesize that changes in estrogen signaling alters myokine expression and intensifies bone loss in women. In our present study, we demonstrate that conditioned media from ovariectomized or skeletal muscle deficient in estrogen receptor α (ERα) expression enhances osteoclast differentiation and activity. Using a cytokine array, we identified myokines that have altered expressions in response to loss of estrogen signaling in muscle. Lastly, we demonstrate that conditional deletion of ERα in skeletal muscle results in osteopenia due to an increase in the osteoclast surface per bone surface. Our results suggest that estrogen signaling modulates expression of myokines that regulate osteoclast differentiation and activity.

Aerobic exercise prevents apoptosis in skeletal muscles of high-fat-fed ovariectomized rats

[Purpose]

Aging and obesity are associated with skeletal muscle atrophy-related signaling pathways, including apoptosis. Many studies have shown that menopause is associated with an increased risk of skeletal muscle atrophy. There is an increasing need to develop strategies that will improve the risk of skeletal muscle atrophy through exercise interventions. However, the effect of exercise on estrogen deficiency-induced apoptosis in skeletal muscles is poorly understood. Therefore, we examined the effects of low-intensity exercise on ovariectomy (OVX)-induced apoptosis of the soleus and plantaris muscles.

[Methods]

The ovaries of all female Sprague-Dawley rats aged 8 weeks, were surgically removed to induce postmenopausal status. The rats were randomly divided into three treatment groups: (1) NSV (normal-diet-sedentary-OVX); (2) HSV (high-fat-diet-sedentary-OVX); and (3) HEV (high-fat-diet-exercise-OVX). The exercise groups were regularly running for 30-40 min/day at 15-18 m/minute, five times/week, for eight weeks.

[Results]

The mRNA levels of Bax significantly decreased in the exercised soleus muscle, and caspase-3 decreased in the plantaris. The skeletal muscle TUNEL-positive apoptotic cells in the high-fat-diet-sedentary OVX rats improved in the treadmill exercise group. Additionally, nuclear caspase-3 levels decreased in the treadmill exercise group compared to those in both sedentary groups. These results suggest that low-intensity treadmill exercise prevents skeletal muscle apoptosis in HFD-fed OVX rats.

[Conclusion]

Induction of HFD in estrogen-deficient mice increased apoptosis in skeletal muscle, which could also be alleviated by low-intensity aerobic exercise. These results may indicate a crucial therapeutic effect of treadmill exercise in preventing skeletal muscle apoptosis in menopausal or post-menopausal women.

Paeoniflorin Alleviates Skeletal Muscle Atrophy in Ovariectomized Mice through the ERα/NRF1 Mitochondrial Biogenesis Pathway

Muscle atrophy in postmenopausal women is caused by estrogen deficiency and a variety of inflammatory factors, including tumor necrosis factor alpha (TNFα). Paeoniflorin (PNF), a natural compound with anti-inflammatory properties, improves estradiol synthesis. Here, we demonstrate that PNF inhibits the progression of TNFα-induced skeletal muscle atrophy after menopause by restoring mitochondrial biosynthesis. Differentiated myoblasts damaged by TNFα were restored by PNF, as evident by the increase in the expression of myogenin (MyoG) and myosin heavy chain 3 (Myh3)—the markers of muscle differentiation. Moreover, diameter of atrophied myotubes was restored by PNF treatment. TNFα-repressed nuclear respiratory factor 1 (NRF1) and mitochondrial transcription factor A (TFAM) (a major regulator of mitochondrial biosynthesis) were restored by PNF, via regulation by estrogen receptor alpha (ERα), an upregulator of NRF1. This mechanism was confirmed in ovariectomized (OVX) mice with a ~40% reduction in the cross-sectional area of the anterior tibialis muscle. OVX mice administered PNF (100, 300 mg/kg/day) for 12 weeks recovered more than ~20%. Behavioral, rotarod, and inverted screen tests showed that PNF enhances reduced muscle function in OVX mice. ERα restored expression of mitofusin 1 (MFN1) and mitofusin 2 (MFN2) (mitochondrial fusion markers) and dynamin-related protein (DRP1) and fission 1 (FIS1) (mitochondrial fission markers). Therefore, PNF can prevent muscle atrophy in postmenopausal women by inhibiting dysfunctional mitochondrial biogenesis.

Short-Term Supplementation With Fermented Red Clover Extract Reduces Vascular Inflammation in Early Post-menopausal Women

The decline in estrogen at menopause poses a critical challenge to cardiovascular and metabolic health. Recently, a growing interest in the role of phytoestrogens, with a particular focus on isoflavones, has emerged as they can bind to estrogen receptors and may mimic the roles of endogenous estrogen. Fermented red clover extract (RC) contains isoflavones with superior bioavailability compared to non-fermented isoflavones, however little is known regarding the impact of isoflavones on cardiovascular and metabolic health. We assessed markers of vascular health in plasma and skeletal muscle samples obtained from healthy but sedentary early post-menopausal women (n = 10; 54 ± 4 years) following 2 weeks of twice daily treatment with placebo (PLA) or RC (60 mg isoflavones per day). The two interventions were administered using a randomized, double-blind, crossover design with a two-week washout period. Plasma samples were utilized for assessment of markers of vascular inflammation. There was a statistically significant reduction (~5.4%) in vascular cell adhesion molecule 1 (VCAM-1) following 2 weeks of RC supplementation compared to PLA (p = 0.03). In contrast, there was no effect of RC supplementation compared to PLA on skeletal muscle estrogen receptor content and enzymes related to vascular function, and angiogenesis. Supplementation with RC reduces vascular inflammation in early post-menopausal women and future studies should address the long-term impact of daily supplementation with RC after menopause.

Estrogen modulates the skeletal muscle regeneration process and myotube morphogenesis: morphological analysis in mice with a low estrogen status

The purpose of this study was to elucidate the functions of estrogen and two estrogen receptors (ERs; ERα and ERβ) in the myoregeneration process and morphogenesis. Cardiotoxin (CTX) was injected into the tibialis anterior (TA) muscles of ovariectomized (OVX) mice to induce muscle injury, and subsequent myoregeneration was morphologically assessed. The diameter of regenerated myotubes in OVX mice was significantly smaller than that in intact mice at all time points of measurement. OVX mice also showed lower muscle recovery rates and slower speeds than did intact mice. ER protein levels showed a predominance of ERβ over ERα in both intact and OVX states. The ERβ level was increased significantly at 7 days after CTX injection in OVX mice and remained at a high level until 14 days. In addition, continuous administration of E2 to OVX mice in which muscle injury was induced resulted in a significantly larger diameter of regenerated myotubes than that in mice that did not receive estrogen. The results indicate that estrogen is an essential factor in the myoregeneration process since estrogen depletion delayed myoregeneration in injured muscles and administration of estrogen under the condition of a low estrogen status rescued delayed myoregeneration. The results strongly suggested that ERβ may be a factor that promotes myoregeneration more than does ERα.

Metabolic Syndrome and Sarcopenia

Skeletal muscle is a major organ of insulin-induced glucose metabolism. In addition, loss of muscle mass is closely linked to insulin resistance (IR) and metabolic syndrome (Met-S). Skeletal muscle loss and accumulation of intramuscular fat are associated with a variety of pathologies through a combination of factors, including oxidative stress, inflammatory cytokines, mitochondrial dysfunction, IR, and inactivity. Sarcopenia, defined by a loss of muscle mass and a decline in muscle quality and muscle function, is common in the elderly and is also often seen in patients with acute or chronic muscle-wasting diseases. The relationship between Met-S and sarcopenia has been attracting a great deal of attention these days. Persistent inflammation, fat deposition, and IR are thought to play a complex role in the association between Met-S and sarcopenia. Met-S and sarcopenia adversely affect QOL and contribute to increased frailty, weakness, dependence, and morbidity and mortality. Patients with Met-S and sarcopenia at the same time have a higher risk of several adverse health events than those with either Met-S or sarcopenia. Met-S can also be associated with sarcopenic obesity. In this review, the relationship between Met-S and sarcopenia will be outlined from the viewpoints of molecular mechanism and clinical impact.

Retinoic acid exerts sexually dimorphic effects on muscle energy metabolism and function

The retinol dehydrogenase Rdh10 catalyzes the rate-limiting reaction that converts retinol into retinoic acid (RA), an autacoid that regulates energy balance and reduces adiposity. Skeletal muscle contributes to preventing adiposity, by consuming nearly half the energy of a typical human. We report sexually dimorphic differences in energy metabolism and muscle function in Rdh10+/- mice. Relative to wild-type (WT) controls, Rdh10+/- males fed a high-fat diet decrease reliance on fatty-acid oxidation and experience glucose intolerance and insulin resistance. Running endurance decreases 40%. Rdh10+/- females fed this diet increase fatty acid oxidation and experience neither glucose intolerance nor insulin resistance. Running endurance increases 220%. We therefore assessed RA function in the mixed-fiber type gastrocnemius muscles (GM), which contribute to running, rather than standing, and are similar to human GM. RA levels in Rdh10+/- male GM decrease 38% relative to WT. Rdh10+/- male GM increase expression of Myog and reduce Eif6 mRNAs, which reduce and enhance running endurance, respectively. Cox5A, complex IV activity, and ATP decrease. Increased centralized nuclei reveal existence of muscle malady and/or repair in GM fibers. Comparatively, RA in Rdh10+/- female GM decreases by less than half the male decrease, from a more modest decrease in Rdh10 and an increase in the estrogen-induced retinol dehydrogenase Dhrs9. Myog mRNA decreases. Cox5A, complex IV activity, and ATP increase. Centralized GM nuclei do not increase. We conclude that Rdh10/RA affects whole body energy use and insulin resistance partially through sexual dimorphic effects on skeletal muscle gene expression, structure, and mitochondria activity.

Impact of premature natural menopause on body composition and physical function in elderly women: A Korean frailty and aging cohort study

Induced premature menopause accelerates the rate of body composition changes (decrease in skeletal muscle mass and increase in fat mass) and deteriorating physical function. However, few studies have focused on the impact of premature natural menopause. This study aimed to investigate the impact of age at natural menopause (ANM) on body composition and physical function in elderly women.Using data from the Korean Frailty and Aging Cohort Study, 765 community-dwelling elderly women aged 70 to 85 years who experienced natural menopause were recruited in this study. Body composition was measured using dual-energy X-ray absorptiometry. Physical function was evaluated by grip strength, the timed up and go test (TUG), and the short physical performance battery (SPPB). Participants were categorized into 4 groups according to their ANM: <40 (premature natural menopause, PNM), 40 to 44 (early natural menopause, ENM), 45 to 54 (normal menopause, NM), and ≥55 (late menopause, LM) years.There were no significant differences in the body composition parameters, such as the appendicular skeletal muscle mass index (PNM: 5.90 ± 0.90 vs ENM: 5.91 ± 0.70 vs NM: 5.85 ± 0.73 vs LM: 5.90 ± 0.75, kg/m2, P = .75) and trunk fat mass index (PNM: 19.4 ± 3.9 vs ENM: 19.9 ± 4.4 vs NM: 19.9 ± 3.9 vs LM: 20.0 ± 3.8, %, P = .87) between the groups. In the physical function evaluation, there was no significant difference between the groups in grip strength (PNM: 19.8 ± 0.6 vs ENM: 20.3 ± 0.4 vs NM: 20.6 ± 0.2 vs LM: 20.6 ± 0.4, kg, P = .53). However, in the TUG (PNM: 11.8 ± 0.4 vs ENM: 10.3 ± 0.3 vs NM: 10.6 ± 0.1 vs LM: 10.2 ± 0.3, seconds, P < .01) and SPPB (PNM: 10.0 ± 0.2 vs ENM: 10.5 ± 0.2 vs NM: 10.6 ± 0.1 vs LM: 10.8 ± 0.2, points, P < .05), the PNM group showed significantly lower values than the other groups did. There was no difference in physical function between the groups except the PNM.Premature natural menopause did not affect the body composition in elderly women but was associated with physical function deterioration. Therefore, more attention should be paid to the prevention of the physical function deterioration caused by premature natural menopause in elderly women.

Differential inflammatory response of men and women subjected to an acute resistance exercise

BACKGROUND

The purpose of this study was to investigate the inflammatory response, lipid peroxidation and muscle damage in men and women athletes subjected to an acute resistance exercise.

METHODS

Twenty college athletes (10 men and 10 women) performed a half-squat exercise consisting of five incremental intensities: 20%, 40%, 60%, 80% and 100% of the one-repetition maximum. Blood samples were collected at rest, 15 min and 24 h post-test. The concentration of lipid peroxidation markers and the activities of a skeletal muscle damage marker and a cardiac muscle damage marker were determined in serum. Serum α-actin was measured as a marker of sarcomere damage. Serum levels of interleukin-6, interleukin-10, and tumor necrosis factor alpha were determined to assess the inflammatory response.

RESULTS

Interleukin-6 levels were higher at 24 h post-test than at rest and 15 min post-test in men (p < 0.05). Moreover, men showed significantly higher hydroperoxide levels in response to resistance exercise at 24 h post-test than at 15 min post-test (p < 0.05). No differences were found in muscle damage parameters regardless of sex or the time point of the test. No differences regarding the studied variables were found when comparing among different time points in women.

CONCLUSION

Our results show a larger influence of half-squat exercises on the release of IL6 and on lipid peroxidation in men than in women at equivalent workloads.

Exercise-Induced Muscle Damage in Postmenopausal Well-Trained Women

BACKGROUND

Sex hormone deprivation derived from menopause may affect exercise-induced muscle damage (EIMD). No studies have previously evaluated this response between postmpenopausal and premenopausal eumenorrheic women over the menstrual cycle.

HYPOTHESIS

Postmenopausal women will present higher EIMD markers than premenopausal women, especially in comparison with the menstrual cycle phases where sex hormone concentrations are higher.

STUDY DESIGN

Cross-sectional study.

LEVEL OF EVIDENCE

Level 3.

METHODS

Thirteen postmenopausal and 19 eumenorrheic women, all of them resistance-trained, performed an eccentric squat-based exercise. The postmenopausal group performed 1 bout of exercise, while the eumenorrheic group performed 3 bouts coinciding with the early follicular, late follicular, and mid-luteal phases ot their menstrual cycle. Muscle soreness, countermovement jump, creatine kinase (CK), myoglobin, lactate dehydrogenase, interleukin-6, tumor necrosis factor-α, and C-reactive protein were evaluated before and postexercise.

RESULTS

The expected differences in sex hormones were observed between groups (P < 0.001) according to their reproductive status. Postexercise increases in CK, myoglobin, and muscle soreness (168.2 ± 45.5 U/L, 123.1 ± 41.5 µg/L, and 20.7 ± 21.3 mm, respectively) were observed in comparison with baseline (136.2 ± 45.5 U/L, 76.9 ± 13.8 µg/L, and 2.7 ± 4.2 mm, respectively). Myoglobin values at baseline in postmenopausal women were higher compared with premenopausal women in the aforementioned menstrual cycle phases, respectively (62.8 ± 8.2, 60.4 ± 7.2, and 60.1 ± 10.6 µg/L; P < 0.001 for all comparisons), which was supported by large effect sizes (0.72-1.08 standardized d units). No postexercise differences were observed between groups in any markers (P > 0.05).

CONCLUSION

Despite higher resting levels of myoglobin and lower strength values in postmenopausal than in premenopausal women, EIMD was similar between both reproductive profiles. This suggests a potential benefit of being physically active despite aging and sex hormone deprivation.

CLINICAL RELEVANCE

Sex hormone deprivation derived from menopause seems not to influence muscle damage reponse to eccentric exercise in resistance-trained postmenopausal women.

An Inverse Relation between Hyperglycemia and Skeletal Muscle Mass Predicted by Using a Machine Learning Approach in Middle-Aged and Older Adults in Large Cohorts

BACKGROUND

Skeletal muscle mass (SMM) and fat mass (FM) are essentially required for health and quality of life in older adults.

OBJECTIVE

To generate the best SMM and FM prediction models using machine learning models incorporating socioeconomic, lifestyle, and biochemical parameters and the urban hospital-based Ansan/Ansung cohort, and to determine relations between SMM and FM and metabolic syndrome and its components in this cohort.

METHODS

SMM and FM data measured using an Inbody 4.0 unit in 90% of Ansan/Ansung cohort participants were used to train seven machine learning algorithms. The ten most essential predictors from 1411 variables were selected by: (1) Manually filtering out 48 variables, (2) generating best models by random grid mode in a training set, and (3) comparing the accuracy of the models in a test set. The seven trained models' accuracy was evaluated using mean-square errors (MSE), mean absolute errors (MAE), and R² values in 10% of the test set. SMM and FM of the 31,025 participants in the Ansan/Ansung cohort were predicted using the best prediction models (XGBoost for SMM and artificial neural network for FM). Metabolic syndrome and its components were compared between four groups categorized by 50 percentiles of predicted SMM and FM values in the cohort.

RESULTS

The best prediction models for SMM and FM were constructed using XGBoost (R2 = 0.82) and artificial neural network (ANN; R2 = 0.89) algorithms, respectively; both models had a low MSE. Serum platelet concentrations and GFR were identified as new biomarkers of SMM, and serum platelet and bilirubin concentrations were found to predict FM. Predicted SMM and FM values were significantly and positively correlated with grip strength (r = 0.726) and BMI (r = 0.915, p < 0.05), respectively. Grip strengths in the high-SMM groups of both genders were significantly higher than in low-SMM groups (p < 0.05), and blood glucose and hemoglobin A1c in high-FM groups were higher than in low-FM groups for both genders (p < 0.05).

CONCLUSION

The models generated by XGBoost and ANN algorithms exhibited good accuracy for estimating SMM and FM, respectively. The prediction models take into account the actual clinical use since they included a small number of required features, and the features can be obtained in outpatients. SMM and FM predicted using the two models well represented the risk of low SMM and high fat in a clinical setting.

Methodological Approach of the Iron and Muscular Damage: Female Metabolism and Menstrual Cycle during Exercise Project (IronFEMME Study)

Abstract

Background: The increase in exercise levels in the last few years among professional and recreational female athletes has led to an increased scientific interest about sports health and performance in the female athlete population. The purpose of the IronFEMME Study described in this protocol article is to determine the influence of different hormonal profiles on iron metabolism in response to endurance exercise, and the main markers of muscle damage in response to resistance exercise; both in eumenorrheic, oral contraceptive (OC) users and postmenopausal well-trained women. Methods: This project is an observational controlled randomized counterbalanced study. One hundered and four (104) active and healthy women were selected to participate in the IronFEMME Study, 57 of which were eumenorrheic, 31 OC users and 16 postmenopausal. The project consisted of two sections carried out at the same time: iron metabolism (study I) and muscle damage (study II). For the study I, the exercise protocol consisted of an interval running test (eight bouts of 3 min at 85% of the maximal aerobic speed), whereas the study II protocol was an eccentric-based resistance exercise protocol (10 sets of 10 repetitions of plate-loaded barbell parallel back squats at 60% of their one repetition maximum (1RM) with 2 min of recovery between sets). In both studies, eumenorrheic participants were evaluated at three specific moments of the menstrual cycle: early-follicular phase, late-follicular phase and mid-luteal phase; OC users performed the trial at two moments: withdrawal phase and active pill phase. Lastly, postmenopausal women were only tested once, since their hormonal status does not fluctuate. The three-step method was used to verify the menstrual cycle phase: calendar counting, blood test confirmation, and urine-based ovulation kits. Blood samples were obtained to measure sex hormones, iron metabolism parameters, and muscle damage related markers. Discussion: IronFEMME Study has been designed to increase the knowledge regarding the influence of sex hormones on some aspects of the exercise-related female physiology. Iron metabolism and exercise-induced muscle damage will be studied considering the different reproductive status present throughout well-trained females’ lifespan.

Trial registration

The study was registered at Clinicaltrials.gov NCT04458662 on 2 July 2020.

Pathophysiology, Biomarkers, and Therapeutic Modalities Associated with Skeletal Muscle Loss Following Spinal Cord Injury

A spinal cord injury (SCI) may lead to loss of strength, sensation, locomotion and other body functions distal to the lesion site. Individuals with SCI also develop secondary conditions due to the lack of skeletal muscle activity. As SCI case numbers increase, recent studies have attempted to determine the best options to salvage affected musculature before it is lost. These approaches include pharmacotherapeutic options, immunosuppressants, physical activity or a combination thereof. Associated biomarkers are increasingly used to determine if these treatments aid in the protection and reconstruction of affected musculature.

Ovariectomy alters lengthening contraction induced heat shock protein expression

Estrogen appears to play a role in minimizing skeletal muscle damage as well as regulating the expression of the protective heat shock proteins (HSPs). To clarify the relationship between estrogen, muscle HSP content, and muscle damage, tibialis anterior (TA) muscles from ovary-intact (OVI; n = 12) and ovariectomized (OVX; 3 weeks, n = 12) female Sprague-Dawley rats were subjected to either 20 or 40 lengthening contractions (LCs). Twenty-four hours after stimulation, TA muscles were removed, processed, and assessed for HSP25 and HSP72 content as well as muscle (damage) morphology. No differences in muscle contractile properties were observed in TA muscles between OVI and OVX animals for peak torque during the LCs. In unstressed TA muscles, the basal expression of HSP72 expression was decreased in OVX animals (P < 0.05) while HSP25 content remained unchanged. Following 20 LCs, HSP25 content was elevated (P < 0.05) in TA muscles from OVX animals but unchanged in muscles from OVI animals. Following 40 LCs, HSP25 content was elevated (P < 0.01) in TA muscles from both OVI and OVX animals while HSP72 content was elevated only in TA muscles from OVI animals (P < 0.05). Taken together, these data suggest the loss of ovarian hormones, such as estrogen, may impair the skeletal muscle cellular stress response thereby rendering muscles more susceptible to certain types of contraction induced damage. Novelty Ovariectomy alters muscle HSP72 content. Muscle contractile measures are maintained following ovariectomy.

Divergent Regulation of Myotube Formation and Gene Expression by E2 and EPA during In-Vitro Differentiation of C2C12 Myoblasts

Estrogen (E2) and polyunsaturated fatty acids (n-3PUFA) supplements independently support general wellbeing and enhance muscle regeneration in-vivo and myotube formation in-vitro. However, the combined effect of E2 and n-3PUFA on myoblast differentiation is not known. The purpose of the study was to identify whether E2 and n-3PUFA possess a synergistic effect on in-vitro myogenesis. Mouse C2C12 myoblasts, a reliable model to reiterate myogenic events in-vitro, were treated with 10nM E2 and 50μM eicosapentaenoic acid (EPA) independently or combined, for 0-24 h or 0-120 h during differentiation. Immunofluorescence, targeted qPCR and next generation sequencing (NGS) were used to characterize morphological changes and differential expression of key genes involved in the regulation of myogenesis and muscle function pathways. E2 increased estrogen receptor α (Erα) and the expression of the mitogen-activated protein kinase 11 (Mapk11) within 1 h of treatment and improved myoblast differentiation and myotube formation. A significant reduction (p < 0.001) in myotube formation and in the expression of myogenic regulatory factors Mrfs (MyoD, Myog and Myh1) and the myoblast fusion related gene, Tmem8c, was observed in the presence of EPA and the combined E2/EPA treatment. Additionally, EPA treatment at 48 h of differentiation inhibited the majority of genes associated with the myogenic and striated muscle contraction pathways. In conclusion, EPA and E2 had no synergistic effect on myotube formation in-vitro. Independently, EPA inhibited myoblast differentiation and overrides the stimulatory effect of E2 when used in combination with E2.

On the horizon of aging and physical activity research

This viewpoint is the result of a Horizon Round Table discussion of Exercise and Aging held during the 2017 Saltin International Graduate School in Exercise and Clinical Physiology in Gatineau, Quebec. This expert panel discussed key issues and approaches to future research into aging, across human physiological systems, current societal concerns, and funding approaches. Over the 60-min round table discussion, 3 major themes emerged that the panel considered to be "On the Horizon" of aging research. These themes include (i) aging is a process that extends from womb to tomb; (ii) the importance of longitudinal experimental studies; and (iii) the ongoing need to investigate multiple systems using an integrative approach between scientists, clinicians, and knowledge brokers. With a focus on these themes, we aim to identify critical questions, challenges, and opportunities that face scientists in advancing the understanding of exercise and aging.

Transwomen in elite sport: scientific and ethical considerations

The inclusion of elite transwomen athletes in sport is controversial. The recent International Olympic Committee (IOC) (2015) guidelines allow transwomen to compete in the women's division if (amongst other things) their testosterone is held below 10 nmol/L. This is significantly higher than that of cis-women. Science demonstrates that high testosterone and other male physiology provides a performance advantage in sport suggesting that transwomen retain some of that advantage. To determine whether the advantage is unfair necessitates an ethical analysis of the principles of inclusion and fairness. Particularly important is whether the advantage held by transwomen is a tolerable or intolerable unfairness. We conclude that the advantage to transwomen afforded by the IOC guidelines is an intolerable unfairness. This does not mean transwomen should be excluded from elite sport but that the existing male/female categories in sport should be abandoned in favour of a more nuanced approach satisfying both inclusion and fairness.

Mechanisms Underlying Metabolic Syndrome-Related Sarcopenia and Possible Therapeutic Measures

Although there are several reviews that report the interrelationship between sarcopenia and obesity and insulin resistance, the relation between sarcopenia and the other signs that compose the metabolic syndrome (MetS) has not been extensively revised. Here, we review the mechanisms underlying MetS-related sarcopenia and discuss the possible therapeutic measures proposed. A vicious cycle between the loss of muscle and the accumulation of intramuscular fat might be associated with MetS via a complex interplay of factors including nutritional intake, physical activity, body fat, oxidative stress, proinflammatory cytokines, insulin resistance, hormonal changes, and mitochondrial dysfunction. The enormous differences in lipid storage capacities between the two genders and elevated amounts of endogenous fat having lipotoxic effects that lead to the loss of muscle mass are discussed. The important repercussions of MetS-related sarcopenia on other illnesses that lead to increased disability, morbidity, and mortality are also addressed. Additional research is needed to better understand the pathophysiology of MetS-related sarcopenia and its consequences. Although there is currently no consensus on the treatment, lifestyle changes including diet and power exercise seem to be the best options.

Handgrip Strength and Its Associated Factors among Community-dwelling Elderly in Sri Lanka: A Cross-sectional Study

PURPOSE

Low muscle strength is central to geriatric physical disabilities and mortality. The purpose of the present study was to examine handgrip strength (HGS) and its associated factors among community-dwelling older people in Sri Lanka.

METHODS

A cross-sectional study was conducted in the Kandy district using multistage sampling. A total of 999 older people were recruited, with a female preponderance. Data were collected using interviewer-administered questionnaires on demographic characteristics, depression, and physical activity. Anthropometric measurements including weight, height, mid-upper arm circumference, calf circumference, and HGS were recorded. Complex sample general linear model was used to examine the association between HGS and its associated factors.

RESULTS

The mean highest HGS of the study group was 12.56 kg (95% confidence interval: 11.94-13.19). Male older people had a higher HGS (17.02, 95% confidence interval: 15.55-18.49 kg) than females (10.59, 95% confidence interval: 10.12-11.06 kg). For both men and women, older age was associated with lower HGS, while mid-upper arm circumference was associated with better HGS. Diabetes mellitus, vegetarian diet, and alcohol consumption were associated with HGS for women only.

CONCLUSION

Men had a higher HGS compared with women. Age, mid-upper arm circumference, diabetes mellitus, vegetarian diet, and alcohol consumption were factors associated with HGS among community-dwelling older people in Kandy district, Sri Lanka. HGS can be used as a feasible strategy to improve health status of older people by community health nurses.

Frailty assessment in older adults with chronic obstructive respiratory diseases

The number of patients with chronic obstructive pulmonary disease (COPD) has been rising with continued exposure to environmental risk factors and aging of populations around the world. Frailty is a geriatric syndrome with a decline in physiological reserve and often coexists with chronic diseases such as COPD. Frailty is an independent risk factor for the development and progression of COPD, and COPD can lead to frailty; treating one might improve the other. Thus, there is an increasing interest in the assessment of frailty in patients with COPD. Furthermore, early identification and assessment of frailty in patients with COPD may affect the choice of intervention and improve its effectiveness. Based on the current literature, the intent of this review was to summarize and discuss frailty assessment tools used for COPD patients and the relevant clinical practices for predicting outcomes. We ascertain that using suitable frailty assessment tools could facilitate physicians to screen and stratify physically frail patients with COPD. Screening appropriately targeted population can achieve better intervention outcomes and pulmonary rehabilitation among frail COPD patients.

Protective effects of gonadal hormones on spinal motoneurons following spinal cord injury

Spinal cord injury (SCI) results in lesions that destroy tissue and disrupt spinal tracts, producing deficits in locomotor and autonomic function. The majority of treatment strategies after SCI have concentrated on the damaged spinal cord, for example working to reduce lesion size or spread, or encouraging regrowth of severed descending axonal projections through the lesion, hoping to re-establish synaptic connectivity with caudal targets. In our work, we have focused on a novel target for treatment after SCI, surviving spinal motoneurons and their target musculature, with the hope of developing effective treatments to preserve or restore lost function following SCI. We previously demonstrated that motoneurons, and the muscles they innervate, show pronounced atrophy after SCI. Importantly, SCI-induced atrophy of motoneuron dendrites can be attenuated by treatment with gonadal hormones, testosterone and its active metabolites, estradiol and dihydrotestosterone. Similarly, SCI-induced reductions in muscle fiber cross-sectional areas can be prevented by treatment with androgens. Together, these findings suggest that regressive changes in motoneuron and muscle morphology seen after SCI can be ameliorated by treatment with gonadal hormones, further supporting a role for steroid hormones as neurotherapeutic agents in the injured nervous system.

The 2017 hormone therapy position statement of The North American Menopause Society

The 2017 Hormone Therapy Position Statement of The North American Menopause Society (NAMS) updates the 2012 Hormone Therapy Position Statement of The North American Menopause Society and identifies future research needs. An Advisory Panel of clinicians and researchers expert in the field of women's health and menopause was recruited by NAMS to review the 2012 Position Statement, evaluate new literature, assess the evidence, and reach consensus on recommendations, using the level of evidence to identify the strength of recommendations and the quality of the evidence. The Panel's recommendations were reviewed and approved by the NAMS Board of Trustees.Hormone therapy (HT) remains the most effective treatment for vasomotor symptoms (VMS) and the genitourinary syndrome of menopause (GSM) and has been shown to prevent bone loss and fracture. The risks of HT differ depending on type, dose, duration of use, route of administration, timing of initiation, and whether a progestogen is used. Treatment should be individualized to identify the most appropriate HT type, dose, formulation, route of administration, and duration of use, using the best available evidence to maximize benefits and minimize risks, with periodic reevaluation of the benefits and risks of continuing or discontinuing HT.For women aged younger than 60 years or who are within 10 years of menopause onset and have no contraindications, the benefit-risk ratio is most favorable for treatment of bothersome VMS and for those at elevated risk for bone loss or fracture. For women who initiate HT more than 10 or 20 years from menopause onset or are aged 60 years or older, the benefit-risk ratio appears less favorable because of the greater absolute risks of coronary heart disease, stroke, venous thromboembolism, and dementia. Longer durations of therapy should be for documented indications such as persistent VMS or bone loss, with shared decision making and periodic reevaluation. For bothersome GSM symptoms not relieved with over-the-counter therapies and without indications for use of systemic HT, low-dose vaginal estrogen therapy or other therapies are recommended.This NAMS position statement has been endorsed by Academy of Women's Health, American Association of Clinical Endocrinologists, American Association of Nurse Practitioners, American Medical Women's Association, American Society for Reproductive Medicine, Asociación Mexicana para el Estudio del Climaterio, Association of Reproductive Health Professionals, Australasian Menopause Society, Chinese Menopause Society, Colegio Mexicano de Especialistas en Ginecologia y Obstetricia, Czech Menopause and Andropause Society, Dominican Menopause Society, European Menopause and Andropause Society, German Menopause Society, Groupe d'études de la ménopause et du vieillissement Hormonal, HealthyWomen, Indian Menopause Society, International Menopause Society, International Osteoporosis Foundation, International Society for the Study of Women's Sexual Health, Israeli Menopause Society, Japan Society of Menopause and Women's Health, Korean Society of Menopause, Menopause Research Society of Singapore, National Association of Nurse Practitioners in Women's Health, SOBRAC and FEBRASGO, SIGMA Canadian Menopause Society, Società Italiana della Menopausa, Society of Obstetricians and Gynaecologists of Canada, South African Menopause Society, Taiwanese Menopause Society, and the Thai Menopause Society. The American College of Obstetricians and Gynecologists supports the value of this clinical document as an educational tool, June 2017. The British Menopause Society supports this Position Statement.

Protective Effects of Estradiol and Dihydrotestosterone following Spinal Cord Injury

Spinal cord injury (SCI) results in lesions that destroy tissue and disrupt spinal tracts, producing deficits in locomotor and autonomic function. We previously demonstrated that motoneurons and the muscles they innervate show pronounced atrophy after SCI, and these changes are prevented by treatment with testosterone. Here, we assessed whether the testosterone active metabolites estradiol and dihydrotestosterone have similar protective effects after SCI. Young adult female rats received either sham or T9 spinal cord contusion injuries and were treated with estradiol, dihydrotestosterone, both, or nothing via Silastic capsules. Basso-Beattie-Bresnahan locomotor testing was performed weekly and voiding behavior was assessed at 3 weeks post-injury. Four weeks after SCI, lesion volume and tissue sparing, quadriceps muscle fiber cross-sectional area, and motoneuron dendritic morphology were assessed. Spontaneous locomotor behavior improved after SCI, but hormone treatments had no effect. Voiding behavior was disrupted after SCI, but was significantly improved by treatment with either estradiol or dihydrotestosterone; combined treatment was maximally effective. Treatment with estradiol reduced lesion volume, but dihydrotestosterone alone and estradiol combined with dihydrotestosterone were ineffective. SCI-induced decreases in motoneuron dendritic length were attenuated by all hormone treatments. SCI-induced reductions in muscle fiber cross-sectional areas were prevented by treatment with either dihydrotestosterone or estradiol combined with dihydrotestosterone, but estradiol treatment was ineffective. These findings suggest that deficits in micturition and regressive changes in motoneuron and muscle morphology seen after SCI are ameliorated by treatment with estradiol or dihydrotestosterone, further supporting a role for steroid hormones as neurotherapeutic agents in the injured nervous system.

Gender in Endocrine Diseases: Role of Sex Gonadal Hormones

Gender- and sex- related differences represent a new frontier towards patient-tailored medicine, taking into account that theoretically every medical specialty can be influenced by both of them. Sex hormones define the differences between males and females, and the different endocrine environment promoted by estrogens, progesterone, testosterone, and their precursors might influence both human physiology and pathophysiology. With the term Gender we refer, instead, to behaviors, roles, expectations, and activities carried out by the individual in society. In other words, "gender" refers to a sociocultural sphere of the individual, whereas "sex" only defines the biological sex. In the last decade, increasing attention has been paid to understand the influence that gender can have on both the human physiology and pathogenesis of diseases. Even the clinical response to therapy may be influenced by sex hormones and gender, but further research is needed to investigate and clarify how they can affect the human pathophysiology. The path to a tailored medicine in which every patient is able to receive early diagnosis, risk assessments, and optimal treatments cannot exclude the importance of gender. In this review, we have focused our attention on the involvement of sex hormones and gender on different endocrine diseases.

Low-intensity aerobic exercise training: inhibition of skeletal muscle atrophy in high-fat-diet-induced ovariectomized rats

PURPOSE

Postmenopausal women are highly susceptible to diseases, such as obesity, type 2 diabetes, osteoporosis, or skeletal muscle atrophy and many people recognize the need for regular physical activity. Aerobic exercise training is known to improve the oxidative capacity and insulin sensitivity of skeletal muscles. This study aimed to investigate the role of low-intensity aerobic exercise training on skeletal muscle protein degradation or synthesis in the plantaris muscles of high-fat-fed ovariectomized rats.

METHODS

Ovariectomized female rats were divided into two groups: a high-fat diet-sedentary group (HFD), and a high-fat diet-aerobic exercise group (HFD+EX). The exercise group exercised aerobically on a treadmill 5 days/week for 8 weeks. The rats progressively ran 30 min/day at 15 m/min, up to 40 min/day at 18 m/min, 0% slope, in the last 4 weeks.

RESULTS

Although aerobic exercise led to significantly increased AMP-activated protein kinase (AMPK) phosphorylation at Thr172, phosphorylation of the mammalian target of rapamycin (mTOR) substrate Thr389 S6K1 level did not decrease. Additionally, even though Akt activity did not increase at Ser473, the atrogin-1 level significantly decreased in the exercise group compared to the non-exercise group. Immunohistochemical staining revealed that high-fat-induced TSC2 protein expression was eliminated in response to aerobic exercise.

CONCLUSION

These results suggest that aerobic exercise can inhibit skeletal muscle protein degradation, but it cannot increase protein synthesis in the plantaris muscle of high-fat-fed ovariectomized rats. Our findings have implications in understanding skeletal muscle mass maintenance with low intensity aerobic exercise in post-menopausal women.

Soymilk Improves Muscle Weakness in Young Ovariectomized Female Mice

Estrogens play a key role in an extensive range of physiological functions in various types of tissues throughout the body in females. We previously showed that estrogen insufficiency caused muscle weakness that could be rescued by estrogen administration in a young female ovariectomized (OVX) mouse model. However, long-term estrogen replacement therapy increases risks of breast cancer and cardiovascular diseases. Soymilk contains plant-based protein and isoflavones that exert estrogen-like activity. Here we examined the effects of prolonged soymilk intake on muscle and its resident stem cells, called satellite cells, in the estrogen-insufficient model. Six-week-old C57BL/6 OVX female mice were fed with a dried soymilk-containing diet. We found that prolonged soymilk intake upregulated grip strength in OVX mice. Correspondingly, cross-sectional area of tibialis anterior muscle was significantly increased in OVX mice fed with soymilk. Furthermore, soymilk diet mitigated dysfunction of satellite cells isolated from OVX mice. Thus, these results indicated that prolonged soymilk intake is beneficial for improving muscle weakness in an estrogen-insufficient state in females.

Ovarian function's role during cancer cachexia progression in the female mouse

Cachexia is a debilitating condition that occurs with chronic disease, including cancer; our research has shown that some regulation of cancer cachexia progression is affected by sex differences. The Apc^Min/+ mouse is genetically predisposed to develop intestinal tumors; IL-6 signaling and hypogonadism are associated with cachexia severity in the male. This relationship in the female warrants further investigation, as we have shown that the ability of IL-6 to induce cachexia differs between the sexes. Since ovarian reproductive function relies on a complex system of endocrine signaling to affect whole body homeostasis, we examined the relationship between ovarian reproductive function and progression of cancer cachexia in the female Apc^Min/+ mouse. Our study of ovarian reproductive function in female Apc^Min/+ mice showed disease-related cessation of estrous cycling (acyclicity) in 38% of mice. Acyclicity, including morphological and functional losses and enhanced muscle inflammatory gene expression, was associated with severe cachexia. Interestingly, ovariectomy rescued body weight and muscle mass and function but increased muscle sensitivity to systemic IL-6 overexpression. In conclusion, our results provide evidence for a relationship between ovarian reproductive function and cachexia progression in female Apc^Min/+ mice.

Acute resistance exercise reduces increased gene expression in muscle atrophy of ovariectomised arthritic rats

Objective

We studied the effect of resistance exercise (RE) on mRNA levels of atrogin-1, MuRF-1, and myostatin in the gastrocnemius muscle of arthritic rats after loss of ovarian function (LOF).

Material and methods

Thirty female Wistar rats (nine weeks old, 195.3 ±17.4 grams) were randomly allocated into five groups: control group (CT-Sham; n = 6); group with rheumatoid arthritis (RA; n = 6); group with rheumatoid arthritis subjected to RE (RAEX; n = 6); ovariectomy group with rheumatoid arthritis (RAOV; n = 6); and an ovariectomy group with rheumatoid arthritis subjected to RE (RAOVEX; n = 6). After 15 days of intra-articular injections with Met-BSA the animals were subjected to RE and six hours after workout were euthanised.

Results

The rheumatoid arthritis provoked reduction in the cross-sectional area (CSA) of muscle fibres, but the CSA was lower in the RAOV when compared to the RA groups. Skeletal muscle atrogin-1 mRNA level was increased in arthritic rats (RA and RAOV), but the atrogin-1 level was higher in RAOV group when compared to other arthritic groups. The Muscle MuRF-1 mRNA level was also increased in the RAOV group. The increased atrogin-1 and MuRF-1 mRNA levels were lower in the RAOVEX group than in the RAOV group. The myostatin mRNA level was similar in all groups, except for the RAOVEX group, in which it was lower than the other groups.

Conclusions

LOF results in increased loss of skeletal muscle-related ubiquitin ligases (atrogin-1 and MuRF-1). However, the RE reduces the atrogin-1, MuRF-1, and myostatin mRNA levels in muscle of arthritic rats affected by LOF.

Modulation of Skeletal Muscle Contraction by Myosin Phosphorylation

The striated muscle sarcomere is a highly organized and complex enzymatic and structural organelle. Evolutionary pressures have played a vital role in determining the structure-function relationship of each protein within the sarcomere. A key part of this multimeric assembly is the light chain-binding domain (LCBD) of the myosin II motor molecule. This elongated "beam" functions as a biological lever, amplifying small interdomain movements within the myosin head into piconewton forces and nanometer displacements against the thin filament during the cross-bridge cycle. The LCBD contains two subunits known as the essential and regulatory myosin light chains (ELC and RLC, respectively). Isoformic differences in these respective species provide molecular diversity and, in addition, sites for phosphorylation of serine residues, a highly conserved feature of striated muscle systems. Work on permeabilized skeletal fibers and thick filament systems shows that the skeletal myosin light chain kinase catalyzed phosphorylation of the RLC alters the "interacting head motif" of myosin motor heads on the thick filament surface, with myriad consequences for muscle biology. At rest, structure-function changes may upregulate actomyosin ATPase activity of phosphorylated cross-bridges. During activation, these same changes may increase the Ca2+ sensitivity of force development to enhance force, work, and power output, outcomes known as "potentiation." Thus, although other mechanisms may contribute, RLC phosphorylation may represent a form of thick filament activation that provides a "molecular memory" of contraction. The clinical significance of these RLC phosphorylation mediated alterations to contractile performance of various striated muscle systems are just beginning to be understood. © 2017 American Physiological Society. Compr Physiol 7:171-212, 2017.

The role of sex steroid hormones in the pathophysiology and treatment of sarcopenia

Sex steroids influence the maintenance and growth of muscles. Decline in androgens, estrogens and progesterone by aging leads to the loss of muscular function and mass, sarcopenia. These steroid hormones can interact with different signaling pathways through their receptors. To date, sex steroid hormone receptors and their exact roles are not completely defined in skeletal and smooth muscles. Although numerous studies focused on the effects of sex steroid hormones on different types of cells, still many unexplained molecular mechanisms in both skeletal and smooth muscle cells remain to be investigated. In this paper, many different molecular mechanisms that are activated or inhibited by sex steroids and those that influence the growth, proliferation, and differentiation of skeletal and smooth muscle cells are reviewed. Also, the similarities of cellular and molecular pathways of androgens, estrogens and progesterone in both skeletal and smooth muscle cells are highlighted. The reviewed signaling pathways and participating molecules can be targeted in the future development of novel therapeutics.

Frailty in Pulmonary and Critical Care Medicine

Conceptualized first in the field of geriatrics, frailty is a syndrome characterized by a generalized vulnerability to stressors resulting from an accumulation of physiologic deficits across multiple interrelated systems. This accumulation of deficits results in poorer functional status and disability. Frailty is a "state of risk" for subsequent disproportionate declines in health status following new exposure to a physiologic stressor. Two predominant models have emerged to operationalize the measurement of frailty. The phenotype model defines frailty as a distinct clinical syndrome that includes conceptual domains such as strength, activity, wasting, and mobility. The cumulative deficit model defines frailty by enumerating the number of age-related things wrong with a person. The biological pathways driving frailty include chronic systemic inflammation, sarcopenia, and neuroendocrine dysregulation, among others. In adults with chronic lung disease, frailty is independently associated with more frequent exacerbations of lung disease, all-cause hospitalization, declines in functional status, and all-cause mortality. In addition, frail adults who become critically ill are more likely develop chronic critical illness or severe disability and have higher in-hospital and long-term mortality rates. The evaluation of frailty appears to provide important prognostic information above and beyond routinely collected measures in adults with chronic lung disease and the critically ill. The study of frailty in these populations, however, requires multipronged efforts aimed at refining clinical assessments, understanding the mechanisms, and developing therapeutic interventions.