Smoking impairs muscle protein synthesis and increases the expression of myostatin and MAFbx in muscle

Smoking cessation only partially reverses cardiac metabolic and structural remodeling in mice

AIMS

Active cigarette smoking is a major risk factor for chronic obstructive pulmonary disease that remains elevated after cessation. Skeletal muscle dysfunction has been well documented after smoking, but little is known about cardiac adaptations to cigarette smoking. The underlying cellular and molecular cardiac adaptations, independent of confounding lifestyle factors, and time course of reversibility by smoking cessation remain unclear. We hypothesized that smoking negatively affects cardiac metabolism and induces local inflammation in mice, which do not readily reverse upon 2-week smoking cessation.

METHODS

Mice were exposed to air or cigarette smoke for 14 weeks with or without 1- or 2-week smoke cessation. We measured cardiac mitochondrial respiration by high-resolution respirometry, cardiac mitochondrial density, abundance of mitochondrial supercomplexes by electrophoresis, and capillarization, fibrosis, and macrophage infiltration by immunohistology, and performed cardiac metabolome and lipidome analysis by mass spectrometry.

RESULTS

Mitochondrial protein, supercomplex content, and respiration (all p < 0.03) were lower after smoking, which were largely reversed within 2-week smoking cessation. Metabolome and lipidome analyses revealed alterations in mitochondrial metabolism, a shift from fatty acid to glucose metabolism, which did not revert to control upon smoking cessation. Capillary density was not different after smoking but increased after smoking cessation (p = 0.02). Macrophage infiltration and fibrosis (p < 0.04) were higher after smoking but did not revert to control upon smoking cessation.

CONCLUSIONS

While cigarette-impaired smoking-induced cardiac mitochondrial function was reversed by smoking cessation, the remaining fibrosis and macrophage infiltration may contribute to the increased risk of cardiovascular events after smoking cessation.

Pre-frailty after blood or marrow transplantation and the risk of subsequent mortality

We examined the prevalence, risk factors, and association between pre-frailty and subsequent mortality after blood or marrow transplantation (BMT). Study participants were drawn from the BMT Survivor Study (BMTSS) and included 3346 individuals who underwent BMT between 1974 and 2014 at one of three transplant centers and survived ≥2 years post-BMT. Participants completed the BMTSS survey at a median of 9 years from BMT and were followed for subsequent mortality for a median of 5 years after survey completion. Closest-age and same-sex biological siblings also completed the survey. Previously published self-reported indices (exhaustion, weakness, low energy expenditure, slowness, unintentional weight loss) classified participants as non-frail (0-1 indices) or pre-frail (2 indices). National Death Index was used to determine vital status and cause of death. Overall, 626 (18.7%) BMT survivors were pre-frail. BMT survivors had a 3.2-fold higher odds of being pre-frail (95% CI = 1.9-5.3) compared to siblings. Compared to non-frail survivors, pre-frail survivors had higher hazards of all-cause mortality (adjusted hazard ratio [aHR] = 1.6, 95% CI = 1.4-2.0). Female sex, pre-BMT radiation, smoking, lack of exercise, anxiety, and severe/life-threatening chronic health conditions were associated with pre-frailty. The novel association between pre-frailty and subsequent mortality provides evidence for interventions as pre-frail individuals may transition back to their robust state.

Effects of cigarette smoking associated with sarcopenia in persons 60 years and older: a cross-sectional study in Zhejiang province

PURPOSE

Smoking is a risk factor for sarcopenia. Nevertheless, few studies analyzed the independent effects of various smoking dimensions (duration, intensity, cumulative dose) on sarcopenia risk. This is a cross-sectional study based on an older population in Zhejiang Province to determine which smoking dimensions are mainly important for sarcopenia risk and to explore the dose-response relationship between them.

METHODS

Our study included 783 patients with sarcopenia and 4918 non-sarcopenic individuals. Logistic regression and restricted cubic with logistic regression (for nonlinear dose effects) were used to obtain odds ratios (ORs) and 95% confidence intervals as well as restricted cubic splines (RCS) curves.

RESULTS

Compared with never-smokers, current smokers had an increased risk of sarcopenia (OR = 1.786; 95% CI 1.387-2.301) after adjusting for confounders such as age, sex, education, alcohol consumption, disease history, etc. There was no significant association between smoking intensity and sarcopenia after more than 20 cigarettes per day (OR = 1.484; 95% CI 0.886-2.487), whereas the risk of sarcopenia increased significantly with increasing duration of smoking after more than 40 years (OR = 1.733; 95% CI 1.214-2.473). Meanwhile, there was a significant non-linear dose-response relationship between smoking duration or intensity and the risk of sarcopenia. However, the risk of sarcopenia increased linearly with the number of pack-years of smoking, which is not a significant nonlinear dose-response relationship.

CONCLUSIONS

This study indicated the association between smoking and sarcopenia. Both smoking duration and cumulative dose were significantly and positively associated with sarcopenia. These findings reflect the important role of the number of years of smoking in increasing the risk of sarcopenia and provide scientific evidence that different smoking dimensions may influence the risk of the sarcopenia.

Musculoskeletal crosstalk in chronic obstructive pulmonary disease and comorbidities: Emerging roles and therapeutic potentials

Chronic Obstructive Pulmonary Disease (COPD) is a multifaceted respiratory disorder characterized by progressive airflow limitation and systemic implications. It has become increasingly apparent that COPD exerts its influence far beyond the respiratory system, extending its impact to various organ systems. Among these, the musculoskeletal system emerges as a central player in both the pathogenesis and management of COPD and its associated comorbidities. Muscle dysfunction and osteoporosis are prevalent musculoskeletal disorders in COPD patients, leading to a substantial decline in exercise capacity and overall health. These manifestations are influenced by systemic inflammation, oxidative stress, and hormonal imbalances, all hallmarks of COPD. Recent research has uncovered an intricate interplay between COPD and musculoskeletal comorbidities, suggesting that muscle and bone tissues may cross-communicate through the release of signalling molecules, known as "myokines" and "osteokines". We explored this dynamic relationship, with a particular focus on the role of the immune system in mediating the cross-communication between muscle and bone in COPD. Moreover, we delved into existing and emerging therapeutic strategies for managing musculoskeletal disorders in COPD. It underscores the development of personalized treatment approaches that target both the respiratory and musculoskeletal aspects of COPD, offering the promise of improved well-being and quality of life for individuals grappling with this complex condition. This comprehensive review underscores the significance of recognizing the profound impact of COPD on the musculoskeletal system and its comorbidities. By unravelling the intricate connections between these systems and exploring innovative treatment avenues, we can aspire to enhance the overall care and outcomes for COPD patients, ultimately offering hope for improved health and well-being.

Associations between life's essential 8 and sarcopenia in US adults: a cross-sectional analysis

Cardiovascular disease (CVD) is closely associated with sarcopenia. We aimed to examine the relationship between Life's Essential 8 (LE8) and the incidence of sarcopenia among adults in the United States. In this study, a cross-sectional analysis was conducted using data from the National Health and Nutrition Examination Survey from 2013 to 2018 and included 5999 adult participants. LE8 score was categorized into low (< 49), moderate (49-79), and high CVH (≥ 79) groups and consisted of health behavior score and health factor score based on American Heart Association definitions. Sarcopenia was defined according to The Foundation for the National Institutes of Health Sarcopenia Project. Multivariate logistic regressions, restricted cubic spline regressions, and subgroup analyses were used to assess the association between LE8 and sarcopenia. LE8 and its subscales score were negatively associated with the incidence of sarcopenia in US adults.

Phenotyping obesity: A focus on metabolically healthy obesity and metabolically unhealthy normal weight

Over the past 4 decades, research has shown that having a normal body weight does not automatically imply preserved metabolic health and a considerable number of lean individuals harbour metabolic abnormalities typically associated with obesity. Conversely, excess adiposity does not always equate with an abnormal metabolic profile. In fact, evidence exists for the presence of a metabolically unhealthy normal weight (MUHNW) and a metabolically healthy obese (MHO) phenotype. It has become increasingly recognised that different fat depots exert different effects on the metabolic profile of each individual by virtue of their location, structure and function, giving rise to these different body composition phenotypes. Furthermore, other factors have been implicated in the aetiopathogenesis of the body composition phenotypes, including genetics, ethnicity, age and lifestyle/behavioural factors. Even though to date both MHO and MUHNW have been widely investigated and documented in the literature, studies report different outcomes on long-term cardiometabolic morbidity and mortality. Future large-scale, observational and population-based studies are required for better profiling of these phenotypes as well as to further elucidate the pathophysiological role of the adipocyte in the onset of metabolic disorders to allow for better risk stratification and a personalised treatment paradigm.

Examining factors contributing to the socioeconomic inequalities in handgrip strength among older adults in India: a decomposition analysis

The purpose of this study was to examine (a) the socioeconomic status (SES)-related inequalities associated with handgrip strength (HGS); and (b) the extent to which several demographic, health, and behavioral factors contributed to such SES disparities in HGS among older adults in India. Data were drawn from the 2017-2018 wave 1 of the Longitudinal Ageing Study of India (LASI). The study sample included 27,707 older adults (13,199 men and 14,508 women) aged 60 years and older. HGS was assessed using a handheld Smedley's Hand Dynamometer with a cut-off of 19.5 kg for men and 12.5 kg for women. Bivariate analysis showed the weighted percentage distribution of weak HGS across respondent characteristics. Multivariate logistic regression assessed factors linked to weak HGS. The concentration curve and index (CCI) was used to determine the inequalities in the prevalence of weak HGS by wealth index scores. Wagstaff's decomposition approach was used to test the contribution of each explanatory variable to weak HGS. Around 9% of older adults in this study reported a weak HGS. It was significantly higher among those aged 80 or older (19.21%) and males (15.55%). Weak HGS was concentrated among older adults from poor SES (CCI: 0.05, p < 0.001). A higher percentage of wealth-based inequality in weak HGS was explained by being underweight (38.83%), belonging to the richest wealth quintile (27.95%), and having a higher subjective social status (32.20%). Moreover, about 23.29% of the inequality in weak HGS was explained by Western region and 22.54% by female gender. Additionally, having a secondary level of education explained a higher percentage (22.09%) of inequality, followed by current working status (- 20.68%). Rural residence (13.08%), limitations in instrumental activities of daily living (IADL) (12.21%), and engagement in yoga-related activities (11.55%) explained a higher percentage of wealth-based inequalities. The findings provide evidence of significant SES-related inequalities in HGS and the contribution of various demographic, health, and behavioral factors to such inequality. As such, public health policies and programs focusing on reducing the burden of disability must consider the contribution of social and economic equity to the preservation of muscle strength among older adults.

Causal associations between genetically determined common psychiatric disorders and the risk of falls: evidence from Mendelian randomization

BACKGROUND

The causal associations between psychiatric disorders and falls risk remains uncertain. Consequently, this study aimed to explore the causal relationship between genetically determined three common psychiatric disorders and the risk of falls based on Mendelian randomization (MR).

METHODS

The genome-wide association study (GWAS) data for schizophrenia (SCZ) (N = 320,404), major depressive disorder (MDD) (N = 480,359), and Alzheimer's disease (AD) (N = 63,926) were obtained as exposures. The GWAS data for falls risk (N = 451,179) was obtained as outcome. Univariate Mendelian randomization (UVMR) was used to evaluate the direct causal relationship between SCZ, MDD, AD, and risk of falls. Inverse variance weighting (IVW) was used as the primary analysis method. Sensitivity analysis was performed to assess the validity of the casualty. Multivariate Mendelian randomization (MVMR) analysis was conducted after adjusting body mass index and smoking initiation. Mediating MR was conducted to calculate the mediating effects of potential intermediaries.

RESULTS

UVMR analysis showed that SCZ (OR 1.02, 95% CI 1.01-1.04, p = 8.03E-03) and MDD (OR 1.15, 95% CI 1.08-1.22, p = 1.38E-05) were positively associated with the risk of falls. Sensitivity analysis results were reliable and robust. MVMR results indicated that the relationship between MDD and SCZ and falls risk remained significant. Mediating MR results demonstrated that smoking initiation mediated partial causal effect of SCZ (0.65%, P = 0.03) and MDD (14.82%, P = 2.02E-03) on risk of falls.

CONCLUSIONS

This study provides genetic evidence for a causal relationship of individuals with SCZ and MDD on an increased risk of falls. Healthcare providers should be aware of the risk of falls in MDD and SCZ patients and develop strategies accordingly.

A Korean Nationwide Cross-Sectional Study Investigating Risk Factors, Prevalence, and Characteristics of Sarcopenia in Men in Early Old Age

The present study investigated the risk factors, prevalence, and characteristics of sarcopenia among men aged 50-64 years. A total of 2868 participants were enrolled in this study. Of these, 328 individuals were classified into a sarcopenia group; the remaining 2540 were assigned to a control group. This study examined several variables, including skeletal muscle mass index, age, height, weight, body mass index, waist circumference, systolic and diastolic blood pressure, fasting glucose, triglyceride and total cholesterol levels, alcohol consumption, and tobacco use. It employed a stratified, clustered, and multistage probability sampling design. Complex sampling was used for the data analysis. The prevalence of sarcopenia was 10.25% (95% CI: 8.98-11.69). All anthropometric measures, including height, weight, BMI, and waist circumference, were significantly different between the two groups (p < 0.05). In terms of blood pressure, only systolic blood pressure (SBP) was significant (p < 0.05), and fasting glucose and triglyceride levels were risk factors for sarcopenia (p < 0.05). Tobacco use differed significantly between the two groups (p < 0.05). This study reported the specific prevalence of sarcopenia and identified its risk factors among men in early old age.

Factors Associated with Sarcopenia among Elderly Individuals Residing in Community and Nursing Home Settings: A Systematic Review with a Meta-Analysis

To investigate the factors associated with sarcopenia in elderly individuals residing in nursing homes and community settings, we conducted a systematic search of databases, including MEDLINE, EMBASE, PubMed, Web of Science and Cochrane, up to May 2023. We incorporated a total of 70 studies into our analysis. Our findings revealed that the prevalence of sarcopenia in nursing homes ranged from 25% to 73.7%, while in community settings, it varied from 5.2% to 62.7%. The factors associated with sarcopenia in both nursing homes and community settings included male gender, BMI, malnutrition, and osteoarthritis. In community settings, these factors comprised age, poor nutrition status, small calf circumference, smoking, physical inactivity, cognitive impairment, diabetes, depression and heart disease. Currently, both the European Working Group on Sarcopenia in Older People (EWGSOP) and the Asian Working Group for Sarcopenia (AWGS) standards are widely utilized in nursing homes and community settings, with the EWGSOP standard being more applicable to nursing homes. Identifying factors associated with sarcopenia is of paramount significance, particularly considering that some of them can be modified and managed. Further research is warranted to investigate the impact of preventive measures on these factors in the management of sarcopenia among elderly individuals residing in nursing homes and community settings.

Associations between indoor air pollution for cooking and heating with muscle and sarcopenia in Chinese older population

BACKGROUND

Exposure to air pollution brings the advent effect for various diseases, but study about the relationship between air pollution and ageing is scant. We aimed to determine the associations between household air pollution for cooking and heating with muscle and sarcopenia in Chinese older population by a nationally representative study.

METHODS

This cross-sectional study included individuals aged 60 and above from the China Health and Retirement Longitudinal Study between 2011 and 2015. The diagnosis of sarcopenia was defined by low muscle mass with low muscle strength and/or reduced physical performance. Generalized additive analyses and dose-dependent analyses with three models were used to assess the effects of different pattern of cooking and heating on muscle and sarcopenia.

RESULTS

A total of 8126 Chinese older individuals with predominant male (53.7%) and mean age of 67.3 ± 6.0 years were included in our study. Solid fuel use in cooking showed significant declines in muscle strength (β = -0.424, 95% CI: -0.767, -0.082, P = 0.01 in model 3) and mass (β = -0.034, 95% CI: -0.051, -0.017, P < 0.01 in model 3), when compared with clean fuel use in cooking, respectively. Solid fuel for heating was correlated with lower muscle strength (β = -0.637, 95% CI: -1.033, -0.241, P < 0.01 in model 3) than clean fuel for heating. The joint use of solid fuel for cooking and heating was associated with reduced muscle strength (β = -0.835, 95% CI: -1.306, -0.365, P < 0.01 in model 3) and mass (β = -0.038, 95% CI: -0.061, -0.015, P < 0.01 in model 3) than clean fuel for cooking and heating. Solid fuel for cooking was associated with significantly increased risk of low muscle strength (adjusted OR = 1.29, 95% CI: 1.11, 1.50, P < 0.01 in model 3) and mass (adjusted OR = 1.35, 95% CI: 1.11, 1.61, P < 0.01 in model 3), possible sarcopenia (adjusted OR = 1.33, 95% CI: 1.19, 1.48, P < 0.01 in model 3) and sarcopenia (adjusted OR = 1.44, 95% CI: 1.21, 1.72, P < 0.01 in model 3) compared with clean fuel for cooking. Solid fuel for heating had a significant correlation with low muscle strength (adjusted OR = 1.30, 95% CI: 1.09, 1.56, P < 0.01 in model 3) and possible sarcopenia (adjusted OR = 1.49, 95% CI: 1.31, 1.70, P < 0.01 in model 3). Dose-dependent manner was shown in the associations between the number of solid fuel with low muscle strength and possible sarcopenia. Clean fuel for cooking and solid fuel for heating was positively associated with the prevalence of possible sarcopenia than clean fuel for cooking and heating (adjusted OR = 1.34, 95% CI: 1.14, 1.57, P < 0.01 in model 3).

CONCLUSIONS

Our findings suggested that solid fuel for cooking and the number of solid fuel use potentially facilitates the onset and progression of muscle loss and sarcopenia.

Smoking during pregnancy is associated with the placental proteome

Maternal smoking during pregnancy (MSDP) is a significant risk factor for the development of foetal, neonatal, and childhood morbidities. We hypothesized that infants exposed to MSDP have a distinct proteomic expression in their term placentas compared to infants without such an exposure. A total of 39 infants exposed (cord blood cotinine levels of >1 ng/mL) and 44 infants not exposed to MSDP were included in the study. Women with chronic disease, body mass index of > 30, or a history of uterine surgery were excluded. Total proteome abundance was analysed with quantitative mass spectrometry. For univariate analysis of differences in placental protein levels between groups, ANOVA with multiple testing corrections by the Benjamini-Hochberg method was used. For multivariate analysis, we used principal component analysis, partial least squares, lasso, random forest, and neural networks. The univariate analyses showed four differentially abundant proteins (PXDN, CYP1A1, GPR183, and KRT81) when heavy and moderate smoking groups were compared to non-smokers. With the help of machine learning, we found that an additional six proteins (SEPTIN3, CRAT, NAAA, CD248, CADM3, and ZNF648) were discriminants of MSDP. The placental abundance of these ten proteins together explained 74.1% of the variation in cord blood cotinine levels (p = 0.002). Infants exposed to MSDP showed differential abundance of proteins in term placentas. We report differential placental abundance of several proteins for the first time in the setting of MSDP. We believe that these findings supplement the current understanding of how MSDP affects the placental proteome.

Smoking Intensity Increases Diaphragm Muscle Injury: A Clinicopathologic Study

BACKGROUND

Studying the effects of smoking intensity is important to evaluate the risk of tobacco use on a range of illnesses, such as as sarcopenia among the elderly. Thus, this study aimed to analyze the effects of pack-years of cigarette smoking on the diaphragm muscle (DIAm) histopathology of postmortem samples.

METHODS

Subjects were divided into three groups: never-smoker (n = 46); less than 30 pack-years of smoking (n = 12); and more than 30 pack-years of smoking (n = 30). Diaphragm samples were stained with Picrosirius red and hematoxylin and eosin stain for general structure.

RESULTS

Participants with more than 30 pack-years of cigarette smoking had a significant increase in adipocytes, blood vessels and collagen deposit, as well as an increase in histopathological alterations.

CONCLUSIONS

Pack-years of smoking was associated with DIAm injury. However, further clinicopathological studies are needed to confirm our findings.

Genetic predisposition to smoking in relation to the risk of frailty in ageing

Frailty causes emerging global health burden due to its high prevalence and mortality. In this study, we used Mendelian randomization (MR) approach to examine the potential causal relationship between smoking and frailty in ageing. Using inverse-variance weighted (IVW) method, genetically predicted smoking initiation was associated with an increased risk of frailty in ageing (odd ratio (OR) 1.23, 95% confidence interval (CI) 1.19-1.27, P = 3.21 × 10^-39). Similarly, per year increase in age of initiation of regular smoking was associated with a 25% decrease in the risk of frailty (95% CI 7-39%, P = 7.79 × 10^-3, per year), while higher number of cigarettes per day was associated with a 12% increased risk (95% CI 4-20%, P = 1.76 × 10^-3). Compared with former smokers, current smokers were associated with an increased risk of frailty (OR 1.12, 95% CI 1.02-1.22, P = 0.01). Lifetime smoking was associated with a 46% higher risk of frailty (95% CI 37-56%, P = 2.63 × 10^-29). Sensitivity analysis using alternative MR methods yielded similar results. Our study indicates that genetic predisposition to smoking is associated with the risk of frailty in ageing. Further studies are warranted to examine the exact role of smoking in the development of frailty.

Gender-Specific Prevalence and Risk Factors of Sarcopenic Obesity in the Korean Elderly Population: A Nationwide Cross-Sectional Study

Sarcopenic obesity (SO) is characterized by the combination of sarcopenia and obesity. This study evaluates the gender-specific prevalence of SO and examines the identified gender-specific risk factors in a community-dwelling elderly population aged 75-84 years. A total of 813 subjects participated in the study via the Korea National Health and Nutrition Examination Survey. The SO prevalence in males and females was 15.46% (95%CI: 11.36-20.70) and 13.59% (95%CI: 10.59-17.28), respectively. The clinical sex-specific risk factors for males were low height, high weight, body mass index, waist circumference, skeletal muscle index, fasting glucose, and triglycerides. The clinical risk factors for females were low height, high weight, body mass index, waist circumference, skeletal muscle index, smoking status, fasting glucose, total cholesterol, and systolic blood pressure. These results are essential to assist healthcare professionals and primary care clinicians with early detection, diagnosis, and intervention for potential SO patients by acknowledging the sex-based prevalence and risk factors.

Relationship among Body Composition, Adipocytokines, and Irisin on Exercise Capacity and Quality of Life in COPD: A Pilot Study

Adipose tissue is an endocrine organ that interferes with the severity of chronic obstructive pulmonary disease (COPD). Although inflammatory markers, body composition, and nutritional status have a significant impact on pulmonary function, the real contribution of adipocytokines and myokines in COPD is still controversial. We aimed to evaluate the role played by the body composition, leptin, adiponectin, haptoglobin, and irisin on the functional exercise capacity, respiratory function, and quality of life (QoL) in COPD. In 25 COPD (20% GOLD-1; 60% GOLD-2; 20% GOLD-3) patients and 26 matched control subjects, we find that leptin, total adiponectin and haptoglobin are significantly increased whereas the 6 min walk test (6MWT) and physical functioning scores are significantly decreased in COPD versus controls. A significant positive relationship is found between leptin and fat mass and between 6MWT and the good health indicators of nutritional status. A significant inverse relationship is found between 6MWT and leptin and fat mass, FEV₁ and haptoglobin, and irisin and haptoglobin. Phase angle and leptin level are significant predictors for functional exercise capacity assessed with 6MWT. Taken altogether, the results of this pilot study further support the role played by body composition and adipocytokines on exercise capacity respiratory function and QoL in COPD.

Understanding the role of smoking and chronic excess alcohol consumption on reduced caloric intake and the development of sarcopenia

This narrative review provides mechanistic insight into the biological link between smoking and/or chronic excess alcohol consumption, and increased risk of developing sarcopenia. Although the combination of excessive alcohol consumption and smoking is often associated with ectopic adipose deposition, this review is focused on the context of a reduced caloric intake (leading to energy deficit) that also may ensue due to either lifestyle habit. Smoking is a primary cause of periodontitis and chronic obstructive pulmonary disease that both induce swallowing difficulties, inhibit taste and mastication, and are associated with increased risk of muscle atrophy and mitochondrial dysfunction. Smoking may contribute to physical inactivity, energy deficit via reduced caloric intake, and increased systemic inflammation, all of which are factors known to suppress muscle protein synthesis rates. Moreover, chronic excess alcohol consumption may result in gut microbiota dysbiosis and autophagy-induced hyperammonemia, initiating the up-regulation of muscle protein breakdown and down-regulation of muscle protein synthesis via activation of myostatin, AMPK and REDD1, and deactivation of IGF-1. Future research is warranted to explore the link between oral healthcare management and personalised nutrition counselling in light of potential detrimental consequences of chronic smoking on musculoskeletal health outcomes in older adults. Experimental studies should investigate the impact of smoking and chronic excess alcohol consumption on the gut-brain axis, and explore biomarkers of smoking-induced oral disease progression. The implementation of behavioural change interventions and health policies regarding smoking and alcohol intake habits may mitigate the clinical and financial burden of sarcopenia on the healthcare system.

Association of dietary and lifestyle inflammation scores with muscle strength and muscle endurance among Tehranian adults

Diet and lifestyle as modifiable factors play an effective role in muscle strength and muscle endurance. In addition, inflammatory reactions may have an association with the etiology of a a lower muscle strength and muscle endurance. We aimed to investigate the association of dietary and lifestyle inflammation scores (DLIS) with muscle strength and muscle endurance in a sample of Iranian adults. In this cross-sectional study, 270 adults aged 20 to 59 years (55.9% female) were selected. The dietary intakes were collected using a 168-item semi-quantitative food frequency questionnaire. The DLIS was calculated using the dietary inflammatory score (DIS), and lifestyle inflammatory score (LIS). Muscle endurance and muscle strength were measured by a digital-handgrip-dynamometer. Multivariate adjusted means for muscle strength and endurance across quartiles of the DIS, LIS, and DLIS were determined by the ANCOVA test. Multiple linear regression analysis was used to evaluate the association between inflammation scores (i.e., DIS, LIS, and DLIS), and muscle strength, muscle endurance. The DLIS ranged between -2.94 and 3.09. The adjusted P-value of muscle strength of the right hand (MSR) along quartiles of DIS was significantly lower (P = 0.024). MSR (β: -1.19; P-value: 0.020) and mean muscle strength (MMS) (β: -0.95; P-value: 0.047) had significant association with DIS. MSR (β: -0.85; P-value: 0.050) had a marginally significant association with DLIS. Overall, we found that a high adherence to a pro-inflammatory diet might be associated to a lower muscle strength. However, a lifestyle with greater inflammatory potential was not related to any components of muscle endurance. Further studies with prospective designs are needed to confirm the present findings in further details.

Secondhand Tobacco Smoke and Functional Impairments in Older Adults Living in the Community

BACKGROUND/AIM

There has been no comprehensive examination of the potential association of SHS with broad functional limitation assessment in older adults, where functional limitations are burdensome and challenging.

METHODS

We examined 2258 community-dwelling non-smoking older adults from the Seniors-Enrica-2-cohort. At baseline (2017) and follow-up (2019) grip strength was measured with a Jamar dynamometer, lower-extremity performance with the Short Physical Performance Battery (SPPB), overall physical function using the physical component summary (PCS) of the Spanish version of the SF-12, frailty with a Deficits Accumulation Index (DAI), and mobility limitations with the Rosow-Breslau scale. Baseline exposure to SHS was assessed by serum cotinine, and past exposure was self-reported. Cross-sectional analyses were performed using linear and logistic regression models, whereas functional performance changes were examined using repeated measures models with robust SE estimates.

RESULTS

Overall, the median (IQR) serum cotinine concentration was 0.079 (0.035-0.175) ng/ml, with 20 participants presenting concentrations ≥3 ng/ml. Compared to the unexposed, fully-adjusted models showed that the highest exposure group (≥0.239 ng/ml) presented lower grip strength (mean difference: -1.05 kg; 95% CI = -1.80, -0.31) and higher DAI scores (1.52; 95% CI = 0.38, 2.66) at baseline. Similarly, in models of self-reported past exposure, never-smokers who had lived with ≥2 smokers or been exposed to higher SHS cumulative doses showed lower baseline SPPB values, higher DAI scores, and higher prevalence of mobility limitations. In prospective analyses, those in the highest quartile of baseline cotinine presented harmful SPPB [-0.24 (-0.46, -0.02)] and DAI [1.28 (0.00, 2.55)] changes, and higher risk of mobility limitations [hazard ratio: 1.64; 95% CI = 1.01, 2.68] than the unexposed.

CONCLUSIONS

SHS exposure over the life-course and during old age may accelerate functional decline.

IMPLICATIONS

This manuscript provides a comprehensive examination of the relationship between secondhand smoke exposure and a broad range of functional limitations in older adults. Results show that: (i) non-smokers who had been exposed to higher cumulative doses of SHS in adulthood show worse physical function than non-exposed. (ii) Exposure to SHS during old age, as measured with cotinine concentrations, is associated with accelerated short-term functional declines. (iii) The effects of SHS are stronger among older adults with chronic morbidities. (iv) Results suggest that more efforts are needed to protect older adults from passive smoking, especially to those with chronic conditions because of their potential greater vulnerability to the effects of SHS.

Dysregulated myokines and signaling pathways in skeletal muscle dysfunction in a cigarette smoke–induced model of chronic obstructive pulmonary disease

Skeletal muscle dysfunction is an important extrapulmonary comorbidity of chronic obstructive pulmonary disease (COPD). Muscle-derived cytokines (myokines) play important roles in skeletal muscle growth and function, but their contributions to skeletal muscle dysfunction in COPD have not been fully understood. In the current study, by using a well-established mouse model of COPD with skeletal muscle dysfunction, we found that the expressions of Fndc5 (fibronectin type III domain-containing protein 5, the precursor of irisin) and peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α) were decreased, while myostatin (Mstn), phosphorylated extracellular regulated kinase (p-Erk1/2), and p-Smad3 expressions were upregulated in skeletal muscles from cigarette smoke-exposed mice and in cigarette smoke extract (CSE)-stimulated C2C12 myotubes. Treatment with Smad3 or Erk1/2 inhibitors partially restored the expression of Fndc5 in CSE-stimulated C2C12 myotubes. Taken together, CSE exposure, by upregulation of p-Erk1/2, promoted the expression of Mstn, which further inhibited Fndc5 expression by the p-Smad3/PGC-1α pathway, revealing a novel regulating mechanism of myokines in the pathogenesis of skeletal muscle comorbidities of COPD.

Benzo[a]pyrene exposure in muscle triggers sarcopenia through aryl hydrocarbon receptor-mediated reactive oxygen species production

BACKGROUND

Benzo[a]pyrene (BaP), a toxic carcinogen, is associated with various adverse effects but is rarely discussed in muscle-related disorders. This study investigated in vitro and in vivo effects triggered by BaP exposure in muscles and hypothesized that exposure might induce conditions similar to sarcopenia due to the shared mechanism of oxidative stress. In vitro experiments used C2C12 mouse myoblasts to examine effects induced by BaP exposure in control (untreated) and BaP-treated (10 µM/ml) muscle cells. An established TNF-α-treated sarcopenia model was utilized to verify our results. In vivo experiments compared immunohistochemical staining of sarcopenia-related markers in rats exposed to clean air and polluted air.

RESULTS

In C2C12 cells, after 2-72 h of BaP exposure, elevated mRNA and protein expressions were observed in aryl hydrocarbon receptor (AhR) and cytochrome P450 1A1, subsequently in ROS (NOX2 and NOX4) production, inflammatory cytokines (IL-6, TNF-α, and NF-kB), and proteins mediating apoptotic cell death (caspase-3 and PARP). Two myokines also altered mRNA and protein expressions akin to changes in sarcopenia, namely decreased irisin levels and increased myostatin levels. In addition, N-acetylcysteine, a well-known antioxidant, led to decrease in oxidative markers induced by BaP. The validation by TNF-α-treated sarcopenia model revealed comparable biological responses in either TNF-α or BaP treated C2C12 cells. In vivo experiments with rats exposed to air pollution showed increased expression of BaP, AhR, 8-hydroxydeoxyguanosine, and myostatin and decreased irisin expression in immunohistochemical staining.

CONCLUSIONS

Our results suggest that BaP exerts deleterious effects on the muscle, leading to conditions indicative of sarcopenia. Antioxidant supplementation may be a treatment option for BaP-induced sarcopenia, but further validation studies are needed.

Impacts of Cigarette Smoke (CS) on Muscle Derangement in Rodents-A Systematic Review

Cigarette smoke (CS) is the major risk factor for chronic obstructive pulmonary disease (COPD) and can induce systemic manifestations, such as skeletal muscle derangement. However, inconsistent findings of muscle derangement were reported in previous studies. The aim of the present study was to consolidate the available evidence and assess the impact of CS on muscle derangement in rodents. A comprehensive literature search of five electronic databases identified ten articles for final analysis. Results showed that the diaphragm, rectus femoris, soleus, and gastrocnemius exhibited significant oxidative to glycolytic fiber conversions upon CS exposure. In contrast, the extensor digitorum longus (EDL), plantaris, and tibialis did not exhibit a similar fiber-type conversion after CS exposure. Hindlimb muscles, including the quadriceps, soleus, gastrocnemius, and EDL, showed significant reductions in the CSA of the muscle fibers in the CS group when compared to the control group. Changes in inflammatory cytokines, exercise capacity, and functional outcomes induced by CS have also been evaluated. CS could induce a shift from oxidative fibers to glycolytic fibers in high-oxidative muscles such as the diaphragm, rectus femoris, and soleus, and cause muscle atrophy, as reflected by a reduction in the CSA of hindlimb muscles such as the quadriceps, soleus, gastrocnemius, and EDL.

Early Life Factors Associated with Lean Body Mass in Spanish Children: CALINA Study

Early life is critical for the programming of body composition. The literature links perinatal factors with fat mass development and its future effects (e.g., obesity); however, little evidence exists between early life factors and lean body mass (LBM). This study follows up on a cohort of 416 Spanish children at ages six to eight, previously evaluated at birth in the CALINA study. Here, we studied the association between early life factors, LBM, and limb strength. Parental origin/nutritional status, maternal smoking during pregnancy, gestational diabetes/weight gain/age, birth weight (BW), early feeding, and rapid weight gain (RWG) were collected from primary care records. Bioimpedance analysis, dual-energy X-ray absorptiometry, peripheral quantitative computed tomography, and a handgrip/standing long jump test were used to assess fat-free mass index (FFMI), total lean soft tissue mass index (TLSTMI), muscle cross-sectional area index (MCSAI), and limb strength, respectively. In girls, maternal smoking, gestational age, and BW were positively associated with FFM/LSTM. In boys, the parents’ BMI, BW, and RWG were positively associated with FFM/LSTM. BW was associated with handgrip strength in both. Maternal BMI in girls and RWG in boys were negatively associated with the standing long jump. Early life programming plays a key role in determining LBM in children.

Association between Elevated Plasma Homocysteine and Low Skeletal Muscle Mass in Asymptomatic Adults

BACKGROUND

Homocysteine has been drawing attention with a closed linkage with skeletal muscle. However, the association of hyperhomocysteinemia with decreased skeletal muscle mass remains unclear. We aimed to investigate the association of hyperhomocysteinemia with low skeletal muscle mass (LMM) in asymptomatic adults.

METHODS

This was a cross-sectional study of 114,583 community-dwelling adults without cancer, stroke, or cardiovascular diseases who underwent measurements of plasma homocysteine and body composition analysis from 2012 to 2018. Hyperhomocysteinemia was defined as >15 μmol/L. Skeletal muscle mass index (SMI) was calculated based on appendicular muscle mass (kg)/height (m)2. Participants were classified into three groups based on SMI: "normal," "mildly low," and "severely low."

RESULTS

The prevalence of hyperhomocysteinemia was the highest in subjects with severely LMM (12.9%), followed by those with mildly LMM (9.8%), and those with normal muscle mass (8.5%) (P for trend <0.001). In a multivariable logistic regression model, hyperhomocysteinemia was significantly associated with having a mildly LMM (odds ratio [OR], 1.305; 95% confidence interval [CI], 1.224 to 1.392) and severely LMM (OR, 1.958; 95% CI, 1.667 to 2.286), respectively. One unit increment of log-transformed homocysteine was associated with 1.360 and 2.169 times higher risk of having mildly LMM and severely LMM, respectively.

CONCLUSION

We demonstrated that elevated homocysteine has an independent association with LMM in asymptomatic adults, supporting that hyperhomocysteinemia itself can be a risk for decline in skeletal musculature.

Moderate Treadmill Training Induces Limited Effects on Quadriceps Muscle Hypertrophy in Mice Exposed to Cigarette Smoke Involving Metalloproteinase 2

Background

Long-term cigarette smoke (CS) induces substantive extrapulmonary effects, including musculoskeletal system disorders. Exercise training seems to protect long-term smokers against fiber atrophy in the locomotor muscles. Nevertheless, the extracellular matrix (ECM) changes in response to aerobic training remain largely unknown. Thus, we investigated the effects of moderate treadmill training on aerobic performance, cross-sectional area (CSA), fiber distribution, and metalloproteinase 2 (MMP-2) activity on quadriceps muscle in mice exposed to chronic CS.

Methods

Male mice were randomized into four groups: control or smoke (6 per group) and exercise or exercise+smoke (5 per group). Animals were exposed to 12 commercially filtered cigarettes per day (0.8 mg of nicotine, 10 mg of tar, and 10 mg of CO per cigarette). The CSA, fibers distribution, and MMP-2 activity by zymography were assessed after a period of treadmill training (50% of maximal exercise capacity for 60 min/day, 5 days/week) for 24 weeks.

Results

The CS exposure did not change CSA compared to the control group (p>0.05), but minor fibers in the frequency distribution (<1000 µm²) were observed. Long-term CS exposure attenuated CSA increases in exercise conditions (smoke+exercise vs exercise) while did not impair aerobic performance. Quadriceps CSA increased in mice nonsmoker submitted to aerobic training (p = 0.001). There was higher pro-MMP-2 activity in the smoke+exercise group when compared to the smoke group (p = 0.01). Regarding active MMP-2, the exercise showed higher values when compared to the control group (p = 0.001).

Conclusion

Moderate treadmill training for 24 weeks in mice exposed to CS did not modify CSA, despite inducing higher pro-MMP-2 activity in the quadriceps muscle, suggesting limited effects on ECM remodeling. Our findings may contribute to new insights into molecular mechanisms for CS conditions.

Apocynin prevents cigarette smoking-induced loss of skeletal muscle mass and function in mice by preserving proteostatic signalling

Background and Purpose

Skeletal muscle dysfunction is a major comorbidity of chronic obstructive pulmonary disease (COPD). This type of muscle dysfunction may be a direct consequence of oxidative insults evoked by cigarette smoke (CS) exposure. The present study examined the effects of a potent Nox inhibitor and reactive oxygen species (ROS) scavenger, apocynin, on CS‐induced muscle dysfunction.

Experimental Approach

Male BALB/c mice were exposed to either room air (sham) or CS generated from nine cigarettes per day, 5 days a week for 8 weeks, with or without the coadministration of apocynin (5 mg·kg⁻¹, i.p.). C2C12 myotubes exposed to either hydrogen peroxide (H₂O₂) or water‐soluble cigarette smoke extract (CSE) with or without apocynin (500 nM) were used as an experimental model in vitro.

Key Results

Eight weeks of CS exposure caused muscle dysfunction in mice, reflected by 10% loss of muscle mass and 54% loss of strength of tibialis anterior which were prevented by apocynin administration. In C2C12 myotubes, direct exposure to H₂O₂ or CSE caused myofibre wasting, accompanied by ~50% loss of muscle‐derived insulin‐like growth factor (IGF)‐1 and two‐fold induction of Cybb, independent of cellular inflammation. Expression of myostatin and MAFbx, negative regulators of muscle mass, were up‐regulated under H₂O₂ but not CSE conditions. Apocynin treatment abolished CSE‐induced Cybb expression, preserving muscle‐derived IGF‐1 expression and signalling pathway downstream of mammalian target of rapamycin (mTOR), thereby preventing myofibre wasting.

Conclusion and Implications

Targeted pharmacological inhibition of Nox‐derived ROS may alleviate the lung and systemic manifestations in smokers with COPD.

Healthy Behaviors Associated with Changes in Mental and Physical Strength in Urban African American and White Adults

Over time, adherence to healthy behaviors may improve physical and mental strength which is essential for successful aging. A plausible mechanism is the reduction of inflammation. Research on the association of risky health behaviors on change in strength with age is limited. This study examined changes in the inflammatory potential of the diet, smoking, illicit drug use with changes in strength in a racially and socioeconomically diverse adult sample from the Healthy Aging in Neighborhoods of Diversity Across the Life Span study. The dietary inflammatory index (DII) was calculated from 35 food components derived from multiple 24-h dietary recalls. Strength was evaluated by handgrip strength (HGS), SF-12 PCS and SF-12 MCS (physical and mental component scores). Repeated measures analyses were used to examine associations. At baseline, mean age was 48.4 ± 0.25 years, 56% of the sample were women, and 58% African American. Significant 4-way interactions were found between age, race, socioeconomic status, and DII for women, on change in HGS (p < 0.05) and in SF-12 PCS (p < 0.05) and for men, in change in SF-12 PCS (p < 0.05). Improvements in SF-12 MCS were associated with all three health behaviors as main effects. This study provided evidence that changes towards improving healthy behaviors, diet with anti-inflammatory potential, not smoking cigarettes and not using illicit drugs, were associated with improved strength. Health professionals, especially registered dietitians and health coaches, should create lifestyle interventions to reduce inflammation targeting change in more than one risky health behavior.

Reduced skeletal muscle endurance and ventilatory efficiency during exercise in adult smokers without airflow obstruction

In adult smokers without airflow obstruction, the contributions of pulmonary and skeletal muscle functions to reduced exercise capacity are unclear. We found that non-COPD smokers had decreased exercise capacity and muscle endurance although strength was preserved compared with never-smoking controls. Exercise endurance was associated with quadriceps endurance and CO transfer factor. Despite similar physical activity levels, smokers developed leg fatigue, breathlessness, and displayed increased ventilation with reduced ventilatory efficiency at lower workloads, without exhibiting ventilatory constraint.

Maternal High Fat Diet Consumption Exaggerates Metabolic Disorders in Mice With Cigarette-Smoking Induced Intrauterine Undernutrition

Objectives: Maternal smoking causes fetal underdevelopment and results in births which are small for gestation age due to intrauterine undernutrition, leading to various metabolic disorders in adulthood. Furthermore, postnatal high fat diet (HFD) consumption is also a potent obesogenic factor, which can interact with maternal smoking. In this study, we aimed to determine whether maternal HFD consumption during pregnancy can reverse the adverse impact of maternal smoking and change the response to postnatal HFD consumption.

Methods: Female mice were exposed to cigarette smoke (SE, 2 cigarettes/day) or sham exposed for 5 weeks before mating, with half of the SE dams fed HFD (43% fat, SE+HFD). The same treatment continued throughout gestation and lactation. Male offspring from each maternal group were fed the same HFD or chow after weaning and sacrificed at 13 weeks.

Results: Maternal SE alone increased body weight and fat mass in HFD-fed offspring, while SE+HFD offspring showed the highest energy intake and glucose metabolic disorder in adulthood. In addition, postnatal HFD increased the body weight and aggravated the metabolic disorder caused by maternal SE and SE+HFD.

Conclusions: Maternal HFD consumption could not ameliorate the adverse effect of maternal SE but exaggerate metabolic disorders in adult offspring. Smoking cessation and a healthy diet are needed during pregnancy to optimize the health outcome in the offspring.

Associations between smoking, sex hormone levels and late-onset hypogonadism in men differ depending on age

Few studies have investigated whether associations between smoking, sex hormone levels, and symptoms of late-onset hypogonadism (LOH) in men are affected by age. This multi-center, cross-sectional study involving 6,296 men aged 40-79 years was conducted between June 1, 2013 and August 31, 2016 in 6 provinces of China. Total testosterone, free testosterone, and Aging Males’ Symptoms scale (AMS) scores were compared depending on smoking status and the number of cigarettes smoked. Total testosterone was higher in smokers than in non-smokers in all except the 70-79 year old subgroup. Free testosterone was higher in smokers than non-smokers for the 40-49 and 50-59 year old subgroups, but not the 60-69 and 70-79 year old subgroups. Total testosterone was positively associated with number of cigarettes consumed in smokers aged 40-49 and 50-59 years. Sexual and somatic AMS scores were higher in current and ex-smokers than in non-smokers in all age subgroups from 40 to 79 years and were negatively associated with cigarette consumption in smokers aged 40-49 years. These results indicate that, as men age, the positive association between smoking and testosterone weakens, while the positive association between smoking and LOH symptoms becomes stronger.

Maintaining Muscle Function Across the Lifespan: The State of Science

Sarcopenia is a geriatric syndrome currently defined as pathological loss of muscle mass and function. Sarcopenia is not only a major contributor to loss of physical function in older adults but is also associated with increased risk of morbidity, mortality, and increased healthcare costs. As a complex and multifactorial syndrome, sarcopenia has been associated with numerous degenerative changes during the aging process, but there is building evidence for significant contributions to the development of sarcopenia from neurodegenerative changes in the peripheral nervous system. A variety of interventions have been investigated for the treatment of sarcopenia, but current management is primarily focused on nutrition and therapeutic exercise interventions. Great strides have been made to improve screening procedures and diagnostic criteria for sarcopenia, but continued optimization of diagnostic and screening strategies is needed to better identify individuals with sarcopenia or at risk of developing sarcopenia. Understanding and addressing the major drivers of sarcopenia pathogenesis will help develop therapeutics that can reduce the impact of sarcopenia on affected individuals and society.

The association between healthy lifestyle score with cardiorespiratory fitness and muscle strength

OBJECTIVE

The association of individual behaviours such as diet, tobacco use, body mass index (BMI) and physical activity have been investigated separately in relevance to cardiorespiratory fitness (CRF) and muscle strength. The purpose of this study is to investigate the combined association of the four mentioned lifestyle factors with cardiorespiratory fitness and muscle strength.

METHODS

This cross-sectional study was conducted on 271 Iranian adults, aged 18-70 years. We developed a healthy lifestyle score (HLS) that ranged from 0 to 103 (higher score reflecting better adherence to healthier lifestyle) and included four lifestyle behavioural components (diet, physical activity, smoking and BMI). The relationship between HLS, CRF and muscle strength was determined using linear and non-linear regression analysis.

RESULTS

HLS score was not significantly associated with VO_2max (mL/kg/min) P = .43; VO_2max (L min) P = .14; VO_2max (LBM) (P = .79) and mean muscle strength (MMS) (kg) (P = .11), muscle strength of right hand (MSR) (kg) (P = .10) and muscle strength of left hand (MSL) (kg) (P = .16) in the unadjusted model. After adjustment for potential confounders, we found a significant association between HLS and Vo_2max (L/min), MMS (kg), MSR (kg) and MSL (kg) (P < .001 for all). Also HLS and MMS (r = .06, P = .31), MSR (r = .07, P = .25), MMS (r = .05, P = .39), VO_2max (mL/kg/min) (r = .01, P = .77), VO_2max (L min) (r = .05, P = .35) and VO_2max (LBM) (r = .002, P = .91) have no statistically significant linear relationship.

CONCLUSION

Adherence to healthy lifestyle may be associated with increased CRF and muscle strength after adjusting for potential confounding variables.

Cigarette Smoking Is Associated With Lower Quadriceps Cross-sectional Area and Attenuation in Older Adults

INTRODUCTION

In addition to well-established links with cardiovascular and respiratory diseases, cigarette smoking may affect skeletal muscle; however, associations with quadriceps atrophy, density, and function are unknown. This study explored the associations of current and former smoking with quadriceps muscle area and attenuation as well as muscle force (assessed as knee extension peak torque) and rate of torque development-a measure of muscle power in older adults.

METHODS

Data from 4469 older adults, aged 66-95 years at baseline in the Age, Gene/Environment Susceptibility-Reykjavik Study with measurements of thigh computed tomography, isometric knee extension testing, self-reported smoking history, and potential covariates were analyzed.

RESULTS

Sex differences were observed in these data; therefore, our final analyses are stratified by sex. In men, both former smokers and current smokers had lower muscle area (with β= -0.10, 95% confidence interval [CI] = -0.17 to -0.03 and β = -0.19, 95% CI = -0.33 to -0.05, respectively) and lower muscle attenuation (ie, higher fat infiltration, β = -0.08, 95% CI = -0.16 to -0.01 and β = -0.17, 95% CI = -0.34 to -0.01, respectively) when compared with never smokers. Smoking status was not associated with male peak torque or rate of torque development. In women, current smoking was associated with lower muscle attenuation (β = -0.24, 95% CI = -0.34 to -0.13) compared to never smoking. Among female smokers (current and former), muscle attenuation and peak torque were lower with increasing pack-years.

CONCLUSIONS

Results suggest that cigarette smoking is related to multiple muscle properties at older age and that these relationships may be different among men and women.

IMPLICATIONS

This article presents novel data, as it examined for the first time the relationship between smoking and computed tomography-derived quadriceps muscle size (cross-sectional area) and attenuation. This study suggests that current cigarette smoking is related to higher muscle fat infiltration, which may have significant health implications for the older population, because of its known association with poor physical function, falls, and hip fractures.

Upper Limb Extremity Muscle-Dysfunction in Chronic Obstructive Pulmonary Disease: A Narrative Review

Background:

Peripheral muscle dysfunction is one of the major comorbidities seen in chronic obstructive pulmonary disease. Focusing more on upper extremity, unsupported elevation of arms results in a change in the recruitment pattern of the respiratory muscles. Over the years, many tests were developed to assess the upper limb capacity and include them in various rehabilitation protocol.

Objective:

To review the evidence on mechanism, tests, and rehabilitation protocol for the upper limb extremity muscle-dysfunction occurring in chronic obstructive pulmonary disease.

Methods:

PubMed and Google scholar databases were searched. Based on the inclusion criteria’s:- Chronic Obstructive Pulmonary Diseases patients, any Randomized Controlled or clinical trials, systematic reviews, explaining upper limb extremity muscle dysfunction, various tests to assess upper limb functional capacity and different ways of upper limb extremity training, a total of 15 articles were retrieved.

Results:

The mechanism of upper extremity muscle dysfunction is now well understood. Various tests were designed in order to assess arm strength, arm endurance and functional capacity. All the studies which included upper limb extremity training as a part of the rehabilitation program, showed beneficial results in terms of reduction of dyspnoea and arm fatigue, as well as improving the activity performing capacity.

Conclusion:

This review concluded that the alteration in the upper limb extremity muscles is an inevitable consequence of chronic obstructive pulmonary diseases, which can be confirmed by various upper extremity tests, with patients responding positively to the upper limb training incorporated during pulmonary rehabilitation protocols.

Relationship between smoking status and muscle strength in the United States older adults

OBJECTIVES

Muscle strength in older adults is associated with greater physical ability. Identifying interventions to maintain muscle strength can therefore improve quality of life. The purpose of this study was to evaluate whether current or former smoking status is associated with a decrease in muscle strength in older adults.

METHODS

Data from the Health and Retirement Study from 2012-2014 were analyzed with regard to maximum dominant hand grip strength, maximum overall hand grip strength, and smoking status (current, former, or never). Unadjusted linear regression was conducted. Other factors known to be related to strength were included in the adjusted linear regression analyses.

RESULTS

For maximum grip strength, the regression coefficient was 4.91 for current smoking (standard error [SE], 0.58; p<0.001), 3.58 for former smoking (SE, 0.43; p<0.001), and 28.12 for never smoking (SE, 0.34). Fully adjusted linear regression on the relationship between dominant hand grip strength and smoking did not yield a significant result. The factors significantly associated with dominant hand grip strength were male sex, younger age, a race/ethnicity of non-Hispanic White or non-Hispanic Black, higher income, morbidity of ≤1 condition, no pain, and moderate or vigorous exercise more than once a week.

CONCLUSIONS

Muscle strength in older adults was not associated with smoking status in the adjusted analysis.

The acute effects of cigarette smoke exposure on muscle fiber type dynamics in rats

Reduced exercise capacity is common in people with chronic obstructive pulmonary diseases (COPD) and chronic smokers and is suggested to be related to skeletal muscle dysfunction. Previous studies using human muscle biopsies have shown fiber-type shifting in chronic smokers particularly those with COPD. These results, however, are confounded with aging effects because people with COPD tend to be older. In the present study, we implemented an acute 7-day cigarette smoke-exposed model using Sprague-Dawley rats to evaluate early effects of cigarette smoking on soleus muscles. Rats (n = 5 per group) were randomly assigned to either a sham air (SA) or cigarette smoking (CS) groups of three different concentrations of total particulate matters (TPM) (CS_TPM2.5, CS_TPM5, CS_TPM10). Significantly lower percentages of type I and higher type IIa fiber were detected in the soleus muscle in CS groups when compared with SA group. Of these, only CS_TMP10 group exhibited significantly lower citrate synthase activity and higher muscle tumor necrosis factor-α level than that of SA group. Tumor necrosis factor-α level was correlated with the percentage of type I and IIa fibers. However, no significant between-group differences were found in fiber cross-sectional area, physical activities, or lung function assessments. In conclusion, acute smoking may directly trigger the onset of glycolytic fiber type shift in skeletal muscle independent of aging.

Muscle mass reduction, low muscle strength, and their combination are associated with arterial stiffness in community-dwelling elderly population: the Wakayama Study

Age-related loss of skeletal muscle mass and function is associated with some predisposing factors that increase the risk of vascular damage. This study aimed to examine whether muscle mass reduction, low muscle strength, and their combination were related to arterial stiffness in community-dwelling elderly population. Study participants consisted of 1046 elderly individuals (aged 72 ± 5 years) without cardiovascular disease, chronic kidney disease, or liver disease. Bioelectrical impedance analysis was performed to estimate appendicular skeletal muscle mass (ASM). A value for ASM was normalized for height (ASM index, kg/m²). Handgrip strength (HGS) was measured using a Smedley grip dynamometer. Brachial-ankle pulse wave velocity (baPWV) was evaluated as an index of arterial stiffness using a simple automatic oscillometric technique. When participants were stratified based on baPWV cut-off values (< 1800 cm/s, 1800 to 1999 cm/s, ≥ 2000 cm/s), ASM index and HGS progressively decreased with an increase in baPWV levels (P for trend < 0.001). In multiple regression analysis, baPWV was significantly associated with ASM index (β = -0.270, P < 0.001) and HGS (β = -0.102, P < 0.001) independent of potential confounding factors. The baPWV of the subgroup with low ASM index and low HGS was significantly higher than that of those with only low ASM index or low HGS (P < 0.001). These results suggest that loss of skeletal muscle mass and function is associated with increased arterial stiffness in the elderly population, and the combination of muscle mass reduction and low muscle strength may lead to greater arterial stiffness than each of the individual conditions.

Evaluation of nutritional status in COPD according to the GOLD-2015 staging system: a prospective observational study

OBJECTIVES

This study aimed to assess nutritional statuses of chronic obstructive pulmonary disease (COPD) patients in four categories of the Global Initiative for Chronic Obstructive Lung Disease (GOLD) 2015 classification and to evaluate associations of body mass index (BMI) and fat-free mass index with respiratory and skeletal muscle strengths.

METHODS

This prospective observational study included COPD patients (≥40 years old) who were followed-up for at least 1 year. Medical histories, smoking status, and anthropometric, spirometry, and hand grip strength measurements were recorded.

RESULTS

This study included 463 COPD patients. They were classified as Group A (n = 119), Group B (n = 58), Group C (n = 117), and Group D (n = 169) according to GOLD. Group D was older (p = 0.001) than other groups. No difference was found among the groups regarding sex (p = 0.163). Fat-free body mass was significantly decreased in Group D compared with Group A (p = 0.014) and BMI were lower in Groups C and D than in other groups (p = 0.001). Spirometry and hand grip strength showed a significant decreasing trend toward Group D (p < 0.001 for both).

CONCLUSIONS

Patients with COPD in advanced-stages had decreased BMI, fat-free body mass, hand grip strength, and respiratory and skeletal muscle functions. Nutritional status should be routinely monitored and considered an important indicator in COPD.

Is vaping better than smoking for cardiorespiratory and muscle function?

Cigarette smoking is a risk factor for respiratory disorders, cardiovascular diseases and even decrements in muscle function. Electronic cigarette use (vaping) is considered a healthier alternative to cigarette smoking and may help in smoking cessation. However, the effects of vaping are not clear yet and particularly the long-term effects of vaping are largely unknown. Some reports suggest that vaping maybe as harmful for e.g. respiratory function, as cigarette smoking. In this narrative review the effects of vaping and cigarette smoking on respiratory, cardiovascular and muscle function are compared. Overall, vaping has been found to cause similar effects as smoking on lung function and cardiovascular function. Future studies are needed to clarify the severity of smoking- and vaping-induced decrements on muscle function.

Exposure to secondhand tobacco smoke is associated with reduced muscle strength in US adults

Secondhand tobacco smoke (SHS) exposure is a well-established risk factor for several diseases in adults. Despite the evidence that active tobacco smoke is harmful for the muscles, the association between SHS and muscle strength is still uncertain.We analyzed data from 5390 nonsmoking U.S. adults aged >30 years who participated in the National Health and Nutrition Examination Survey (NHANES) 2011-2014. Exposure to SHS was assessed with serum cotinine concentrations. Grip strength was measured using a Takei digital handgrip dynamometer, and combined grip strength was calculated as the sum of the largest reading from each hand. Median (interquartile range) serum cotinine and grip strength were 0.015 ng/mL (IQR 0.011-0.36) and 65.5 kg (IQR 53.4-86.4), respectively. After adjusting for sociodemographic, anthropometric, health-related behavioral, and clinical risk factors, the highest (0.047-9.9 ng/mL) vs lowest (≤0.011 ng/mL) quartile of serum cotinine was associated with a reduction in combined grip strength of 1.41 kg (95%CI: -2.58, -0.24), p-trend=0.02. These results were consistent across socio-demographic and clinical subgroups. In the US nonsmoking adult population, even low levels of exposure to passive smoking were associated with decreased grip strength. Despite great achievements in tobacco control, extending public health interventions to reduce SHS exposure is still needed.

Predicted lean body mass, fat mass and risk of lung cancer: prospective US cohort study

An inverse association between body mass index (BMI) and risk of lung cancer has been reported. However, the association of body composition such as fat mass (FM) and lean body mass (LBM) with risk of lung cancer has not been fully investigated. Using two large prospective cohort studies (Nurses' Health Study, 1986-2014; Health Professionals Follow-up Study, 1987-2012) in the United States, we included 100,985 participants who were followed for occurrence of lung cancer. Predicted FM and LBM derived from validated anthropometric prediction equations were categorized by sex-specific deciles. During an average 22.3-year follow-up, 2615 incident lung cancer cases were identified. BMI showed an inverse association with lung cancer risk. Participants in the 10th decile of predicted FM and LBM had a lower risk of lung cancer compared with those in the 1st decile, but when mutually adjusted for each other, predicted FM was not associated with lung cancer risk (adjusted hazard ratio [aHR] = 0.98, 95% confidence interval [CI] 0.72-1.35; P(trend) = 0.97) whereas predicted LBM had an inverse association (aHR = 0.73, 95% CI 0.53-1.00; P(trend) = 0.03), especially among participants who were current smokers or had smoked in the previous 10 years (aHR = 0.55, 95% CI 0.36-0.84; P(trend) = 0.008). In conclusion, BMI was inversely associated with lung cancer risk. Based on anthropometric prediction equations, low LBM rather than low FM accounted for the inverse association between BMI and lung cancer risk.

Preserved anabolic threshold and capacity as estimated by a novel stable tracer approach suggests no anabolic resistance or increased requirements in weight stable COPD patients

BACKGROUND & AIMS

Assessing the ability to respond anabolic to dietary protein intake during illness provides important insight in the capacity of lean body mass maintenance. We applied a newly developed stable tracer approach to assess in one session in patients with chronic obstructive pulmonary disease (COPD) and healthy older adults both the minimal amount of protein intake to obtain protein anabolism (anabolic threshold) and the efficiency of dietary protein to promote protein anabolism (anabolic capacity).

METHODS

We studied 12 clinically and weight stable patients with moderate to very severe COPD (mean ± SE forced expiratory volume in 1 s: 36 ± 3% of predicted) and 10 healthy age-matched older adults. At 2-h intervals and in consecutive order, all participants consumed a mixture of 0.0, 0.04, 0.10 and 0.30 g hydrolyzed casein protein×kg ffm-1×2 h-1 and carbohydrates (2:1). We assessed whole body protein synthesis (PS), breakdown (PB), net PS (PS-PB) and net protein balance (phenylalanine (PHE) intake - PHE to tyrosine (TYR) hydroxylation) by IV primed and continuous infusion of L-[ring-2H5]PHE and L-[13C9,15N]-TYR. Anabolic threshold (net protein balance = 0) and capacity (slope) were determined on an individual basis from the assumed linear relationship between protein intake and net protein balance.

RESULTS

We confirmed a linear relationship between protein intake and net protein balance for all participants (R2 range: 0.9988-1.0, p ≤ 0.0006). On average, the anabolic threshold and anabolic capacity were comparable between the groups (anabolic threshold COPD vs. healthy: 3.82 ± 0.31 vs. 4.20 ± 0.36 μmol PHE × kg ffm-1 × hr-1; anabolic capacity COPD vs. healthy: 0.952 ± 0.007 and 0.954 ± 0.004). At protein intake around the anabolic threshold (0.04 and 0.10 g protein×kg ffm-1×2 h-1), the increase in net PS resulted mainly from PB reduction (p < 0.0001) whereas at a higher protein intake (0.30 g protein×kg ffm-1×2 h-1) PS was also stimulated (p < 0.0001).

CONCLUSIONS

The preserved anabolic threshold and capacity in clinically and weight stable COPD patients suggests no disease related anabolic resistance and/or increased protein requirements.

TRIAL REGISTRY

ClinicalTrials.gov; No. NCT01734473; URL: www.clinicaltrials.gov.

Skeletal muscle atrogenes: From rodent models to human pathologies

Skeletal muscle atrophy is a common side effect of most human diseases. Muscle loss is not only detrimental for the quality of life but it also dramatically impairs physiological processes of the organism and decreases the efficiency of medical treatments. While hypothesized for years, the existence of an atrophying programme common to all pathologies is still incompletely solved despite the discovery of several actors and key regulators of muscle atrophy. More than a decade ago, the discovery of a set of genes, whose expression at the mRNA levels were similarly altered in different catabolic situations, opened the way of a new concept: the presence of atrogenes, i.e. atrophy-related genes. Importantly, the atrogenes are referred as such on the basis of their mRNA content in atrophying muscles, the regulation at the protein level being sometimes more complicate to elucidate. It should be noticed that the atrogenes are markers of atrophy and that their implication as active inducers of atrophy is still an open question for most of them. While the atrogene family has grown over the years, it has mostly been incremented based on data coming from rodent models. Whether the rodent atrogenes are valid for humans still remain to be established. An "atrogene" was originally defined as a gene systematically up- or down-regulated in several catabolic situations. Even if recent works often restrict this notion to the up-regulation of a limited number of proteolytic enzymes, it is important to keep in mind the big picture view. In this review, we provide an update of the validated and potential rodent atrogenes and the metabolic pathways they belong, and based on recent work, their relevance in human physio-pathological situations. We also propose a more precise definition of the atrogenes that integrates rapid recovery when catabolic stimuli are stopped or replaced by anabolic ones.

Cardiopulmonary and Muscular Interactions: Potential Implications for Exercise (In)tolerance in Symptomatic Smokers Without Chronic Obstructive Pulmonary Disease

Smoking and physical inactivity are important preventable causes of disability and early death worldwide. Reduced exercise tolerance has been described in smokers, even in those who do not fulfill the extant physiological criteria for chronic obstructive pulmonary disease (COPD) and are not particularly sedentary. In this context, it is widely accepted that exercise capacity depends on complex cardio-pulmonary interactions which support oxygen (O₂) delivery to muscle mitochondria. Although peripheral muscular factors, O₂ transport disturbances (including the effects of increased carboxyhemoglobin) and autonomic nervous system unbalance have been emphasized, other derangements have been more recently described, including early microscopic emphysema, pulmonary microvascular disease, ventilatory and gas exchange inefficiency, and left ventricular diastolic dysfunction. Using an integrative physiological approach, the present review summarizes the recent advances in knowledge on the effects of smoking on the lung-heart-muscle axis under the stress of exercise. Special attention is given to the mechanisms connecting physiological abnormalities such as early cardio-pulmonary derangements, inadequate oxygen delivery and utilization, and generalized bioenergetic disturbances at the muscular level with the negative sensations (sense of heightened muscle effort and breathlessness) that may decrease the tolerance of smokers to physical exercise. A deeper understanding of the systemic effects of smoking in subjects who did not (yet) show evidences of COPD and ischemic heart disease - two devastating smoking related diseases - might prove instrumental to fight their ever-growing burden.

Impact of transcutaneous neuromuscular electrical stimulation or resistance exercise on skeletal muscle mRNA expression in COPD

Background: Voluntary resistance exercise (RE) training increases muscle mass and strength in patients with chronic obstructive pulmonary disease (COPD). Nonvolitional transcutaneous neuromuscular electrical stimulation (NMES) may be an alternative strategy for reducing ambulatory muscle weakness in patients unable to perform RE training, but little comparative data are available. This study, therefore, investigated changes in muscle mRNA abundance of a number of gene targets in response to a single bout of NMES compared with RE. Methods: Twenty-six patients with stable COPD (15 male; FEV₁, 43±18% predicted; age, 64±8 years; fat free mass index, 16.6±1.8 kg/m²) undertook 30 minutes of quadriceps NMES (50 Hz, current at the limit of tolerance) or 5×30 maximal voluntary isokinetic knee extensions. Vastus lateralis muscle biopsies were obtained at rest immediately before and 24 hours after intervention. Expression of 384 targeted mRNA transcripts was assessed by real time TaqMan PCR. Significant change in expression from baseline was determined using the ΔΔC_T method with a false discovery rate (FDR) of <5%. Results: NMES and RE altered mRNA abundance of 18 and 68 genes, respectively (FDR <5%), of which 14 genes were common to both interventions and of the same magnitude of fold change. Biological functions of upregulated genes included inflammation, hypertrophy, muscle protein turnover, and muscle growth, whilst downregulated genes included mitochondrial and cell signaling functions. Conclusions: Compared with NMES, RE had a broader impact on mRNA abundance and, therefore, appears to be the superior intervention for maximizing transcriptional responses in the quadriceps of patients with COPD. However, if voluntary RE is not feasible in a clinical setting, NMES by modifying expression of genes known to impact upon muscle mass and strength may have a positive influence on muscle function.

Smoking and Diabetes as Predictive Factors of Accelerated Loss of Muscle Mass in Middle-Aged and Older Women: A Six-Year Retrospective Cohort Study

Background: Preservation of muscle mass during aging reduces the risk of frailty and age-related chronic diseases. We investigated the lifestyle, psychological factors, and common cardiometabolic diseases associated with accelerated muscle loss in middle-aged and older women. Materials and Methods: A total of 881 women aged 40 years and older who underwent regular health checkup at a tertiary care hospital in Korea in 2010-2011 and underwent a 6-year follow-up were included in this study. Lifestyle and health statuses were evaluated through a standardized questionnaire and laboratory testing. Muscle mass was estimated using bioelectrical impedance analysis. Results: The accelerated loss group showing appendicular skeletal muscle mass (ASM) loss >3% for 6 years represented 24.4% (n = 215) of the total participants. Current smoking women presented a higher odds ratio (OR) for accelerated loss of ASM than nonsmoking individuals after adjusting for age, body mass index, exercise, caloric intake, alcohol consumption, menopausal state, and diabetes mellitus (DM) (OR 3.53, confidence interval [95% CI] 1.28-9.74, p = 0.015). Women with DM showed a higher OR than non-DM individuals after adjusting for the aforementioned variables and smoking status (OR 2.92, 95% CI 1.39-6.14, p = 0.005). Conclusion: Current smoking and DM are predictors for accelerated muscle mass loss in middle-aged and older women. Smokers and DM patients need to monitor muscle mass changes and apply preventive intervention steps. Smoking cessation and good glycemic control are required not only for reducing cardiovascular risk but also for improving muscle health.

Muscle Dysfunction in Smokers and Patients With Mild COPD: A SYSTEMATIC REVIEW

PURPOSE

To describe and discuss the available evidence in the literature concerning muscle function and the association between smoking and muscle dysfunction in smokers and patients with mild chronic obstructive pulmonary disease (COPD).

METHODS

The literature search involved the following databases: PubMed, Pedro, CINAHL, Cochrane Library, Lilacs, and EMBASE. Studies were included if they investigated muscle strength and/or endurance and/or cross-sectional area (CSA) in smokers and/or patients with COPD classified as Global Initiative for Obstructive Lung Disease (GOLD) I and without lung cancer. Two authors screened and identified the studies for inclusion.

RESULTS

Eighteen studies were identified. Some studies found lower values in a variety of muscle strength variables in smokers compared with nonsmoking controls, whereas others found similar values between these groups. When comparing patients with COPD classified as GOLD I with smokers, COPD patients showed lower muscle strength. Two studies found no differences in muscle CSA between smokers compared with nonsmoking controls. Some preliminary evidence also shows that patients with COPD classified as GOLD I had lower CSA in comparison with smokers.

CONCLUSION

Results concerning muscle dysfunction in smokers are divergent, since some studies have shown worse results in a variety of muscle strength variables in smokers compared with nonsmoking controls, whereas other studies have not. Moreover, there is rather preliminary evidence indicating worse muscle dysfunction and lower CSA in patients with mild COPD in comparison with healthy (or non-COPD) smokers.