BACKGROUND:Skeletal muscle aging is associated with various chronic diseases.Exercise is considered an important means to delay this process,but the multimechanism regulation of exercise intervention strategies still requires in-depth exploration.OBJECTIVE:To systematically outline the main physiological changes in skeletal muscle aging and explore the multiple mechanisms by which exercise regulates these changes,thereby providing a theoretical basis for basic research and clinical applications.METHODS:By searching databases such as Web of Science,PubMed,Embase,CNKI,WanFang,and VIP,relevant literature from database inception to October 2024 was retrieved by the first author,including original research articles and reviews.The search terms were"skeletal muscle aging,sarcopenia,exercise regulation,physical activity,chronic inflammation,inflammaging,mitochondrial dysfunction,extracellular matrix fibrosis,lipid mediators,satellite cells"in English and Chinese.Literature was screened based on inclusion and exclusion criteria,and the included 95 articles underwent quality assessment and data extraction.RESULTS AND CONCLUSION:(1)The core manifestations of skeletal muscle aging are the decline in muscle mass,strength,and function,closely related to various physiological changes.The decreased protein synthesis capacity and accelerated degradation rate in muscles lead to muscle atrophy and functional decline.Additionally,dysfunction of satellite cells is considered a key factor in the reduced regenerative capacity of muscles.Mitochondrial dysfunction is another important factor leading to muscle fatigue and energy metabolism disorders,directly affecting the metabolic activity and endurance of skeletal muscles.Chronic inflammatory responses and extracellular matrix fibrosis further exacerbate muscle aging.These factors interact synergistically,collectively resulting in skeletal muscle degeneration.(2)Exercise is widely recognized as an important means to delay skeletal muscle aging.Exercise alleviates chronic low-grade inflammatory responses in skeletal muscle by regulating the immune system,increasing the secretion of anti-inflammatory factors,and inhibiting the expression of pro-inflammatory factors,thereby mitigating the damage of inflammation to muscles.Exercise also enhances mitochondrial biogenesis and function,improves the muscle's energy metabolism capacity,and consequently increases endurance and strength.Furthermore,exercise regulates lipid metabolism and the synthesis of lipid mediators,reduces fat accumulation and alleviates fat-induced inflammatory responses,thereby further protecting skeletal muscles.The mechanical stimulation from exercise promotes the remodeling of the extracellular matrix,reduces fibrosis occurrence,and improves muscle structure and function.Additionally,exercise activates satellite cells,enhancing the regenerative capacity of skeletal muscles,especially notable with strength training and high-intensity interval training.(3)Future research should include large-scale,multicenter clinical trials to evaluate the comprehensive effects of long-term exercise interventions on skeletal muscle aging.By analyzing data from genomics,metabolomics,and other fields,exploring individual differences in responses to exercise interventions can provide more precise theoretical bases for personalized exercise strategies.Besides exercise,the impacts of other interventions such as nutritional supplementation and pharmacological treatments on skeletal muscle aging should not be overlooked.Future studies can explore the combined use of exercise with these interventions to achieve more significant effects.

BACKGROUND:Skeletal muscle aging is associated with various chronic diseases.Exercise is considered an important means to delay this process,but the multimechanism regulation of exercise intervention strategies still requires in-depth exploration.OBJECTIVE:To systematically outline the main physiological changes in skeletal muscle aging and explore the multiple mechanisms by which exercise regulates these changes,thereby providing a theoretical basis for basic research and clinical applications.METHODS:By searching databases such as Web of Science,PubMed,Embase,CNKI,WanFang,and VIP,relevant literature from database inception to October 2024 was retrieved by the first author,including original research articles and reviews.The search terms were"skeletal muscle aging,sarcopenia,exercise regulation,physical activity,chronic inflammation,inflammaging,mitochondrial dysfunction,extracellular matrix fibrosis,lipid mediators,satellite cells"in English and Chinese.Literature was screened based on inclusion and exclusion criteria,and the included 95 articles underwent quality assessment and data extraction.RESULTS AND CONCLUSION:(1)The core manifestations of skeletal muscle aging are the decline in muscle mass,strength,and function,closely related to various physiological changes.The decreased protein synthesis capacity and accelerated degradation rate in muscles lead to muscle atrophy and functional decline.Additionally,dysfunction of satellite cells is considered a key factor in the reduced regenerative capacity of muscles.Mitochondrial dysfunction is another important factor leading to muscle fatigue and energy metabolism disorders,directly affecting the metabolic activity and endurance of skeletal muscles.Chronic inflammatory responses and extracellular matrix fibrosis further exacerbate muscle aging.These factors interact synergistically,collectively resulting in skeletal muscle degeneration.(2)Exercise is widely recognized as an important means to delay skeletal muscle aging.Exercise alleviates chronic low-grade inflammatory responses in skeletal muscle by regulating the immune system,increasing the secretion of anti-inflammatory factors,and inhibiting the expression of pro-inflammatory factors,thereby mitigating the damage of inflammation to muscles.Exercise also enhances mitochondrial biogenesis and function,improves the muscle's energy metabolism capacity,and consequently increases endurance and strength.Furthermore,exercise regulates lipid metabolism and the synthesis of lipid mediators,reduces fat accumulation and alleviates fat-induced inflammatory responses,thereby further protecting skeletal muscles.The mechanical stimulation from exercise promotes the remodeling of the extracellular matrix,reduces fibrosis occurrence,and improves muscle structure and function.Additionally,exercise activates satellite cells,enhancing the regenerative capacity of skeletal muscles,especially notable with strength training and high-intensity interval training.(3)Future research should include large-scale,multicenter clinical trials to evaluate the comprehensive effects of long-term exercise interventions on skeletal muscle aging.By analyzing data from genomics,metabolomics,and other fields,exploring individual differences in responses to exercise interventions can provide more precise theoretical bases for personalized exercise strategies.Besides exercise,the impacts of other interventions such as nutritional supplementation and pharmacological treatments on skeletal muscle aging should not be overlooked.Future studies can explore the combined use of exercise with these interventions to achieve more significant effects.

Objective:To investigate the association between blood selenium levels and sex hormones in Chinese men aged 18-79 years.Methods:Data were derived from the China National Human Biomonitoring survey conducted in 2017-2018, with a final sample size of 5 414 men. General demographic characteristics, behavioral habits, and dietary frequency were collected through questionnaires and physical examinations. Fasting blood samples were collected to measure blood lead, serum testosterone, and estradiol levels. Complex sampling linear regression models were used to analyze the associations between blood selenium levels and testosterone, estradiol, and the testosterone/estradiol ratio, adjusting for confounding factors including age, education level, marital status, smoking status, alcohol consumption, seafood intake, soy product intake, protein supplement intake, BMI, and diabetes status.Results:The mean age of the 5 414 participants was (46.85±27.91) years; 4 774 (91.65%) were of Han ethnicity and 4 505 (86.68%) were married. The median ( Q1, Q3) blood selenium concentration in men was 97.80 (80.64, 116.99) μg/L. After adjusting for confounding factors, the complex sampling linear regression model revealed negative associations between blood selenium levels and both testosterone levels and the testosterone/estradiol ratio, with a significant linear trend ( Ptrend<0.05). Compared with the Q1 group, the β (95% CI) values for testosterone in the Q2, Q3, and Q4 groups were -0.02 (-0.06 to 0.02), -0.03 (-0.08 to 0.01), and -0.06 (-0.09 to -0.02), respectively. Similarly, the β (95% CI) values for the testosterone/estradiol ratio in the Q2, Q3, and Q4 groups were -0.01 (-0.03 to 0.02), -0.01 (-0.04 to 0.04), and -0.03 (-0.06 to -0.01), respectively. Subgroup analysis indicated stronger associations between blood selenium levels and testosterone/estradiol levels in non-smoking and obese men (BMI≥28 kg/m2). Conclusion:Blood selenium levels are negatively associated with testosterone levels and the testosterone/estradiol ratio in Chinese adult males.

Objective:To investigate the association between blood selenium levels and sex hormones in Chinese men aged 18-79 years.Methods:Data were derived from the China National Human Biomonitoring survey conducted in 2017-2018, with a final sample size of 5 414 men. General demographic characteristics, behavioral habits, and dietary frequency were collected through questionnaires and physical examinations. Fasting blood samples were collected to measure blood lead, serum testosterone, and estradiol levels. Complex sampling linear regression models were used to analyze the associations between blood selenium levels and testosterone, estradiol, and the testosterone/estradiol ratio, adjusting for confounding factors including age, education level, marital status, smoking status, alcohol consumption, seafood intake, soy product intake, protein supplement intake, BMI, and diabetes status.Results:The mean age of the 5 414 participants was (46.85±27.91) years; 4 774 (91.65%) were of Han ethnicity and 4 505 (86.68%) were married. The median ( Q1, Q3) blood selenium concentration in men was 97.80 (80.64, 116.99) μg/L. After adjusting for confounding factors, the complex sampling linear regression model revealed negative associations between blood selenium levels and both testosterone levels and the testosterone/estradiol ratio, with a significant linear trend ( Ptrend<0.05). Compared with the Q1 group, the β (95% CI) values for testosterone in the Q2, Q3, and Q4 groups were -0.02 (-0.06 to 0.02), -0.03 (-0.08 to 0.01), and -0.06 (-0.09 to -0.02), respectively. Similarly, the β (95% CI) values for the testosterone/estradiol ratio in the Q2, Q3, and Q4 groups were -0.01 (-0.03 to 0.02), -0.01 (-0.04 to 0.04), and -0.03 (-0.06 to -0.01), respectively. Subgroup analysis indicated stronger associations between blood selenium levels and testosterone/estradiol levels in non-smoking and obese men (BMI≥28 kg/m2). Conclusion:Blood selenium levels are negatively associated with testosterone levels and the testosterone/estradiol ratio in Chinese adult males.

Objective:To establish the prediction model for postoperative delirium in elderly patients with mild stroke undergoing non-cardiac and non-intracranial surgery.Methods:This was a nested case-control study. Seven hundred and fifty elderly patients of either sex with mild stroke, aged ≥65 yr, undergoing elective surgical procedures under general anesthesia in the Department of Gastrointestinal Surgery, Orthopedics and Urology at the Tangshan Workers Hospital from May to December 2023, were selected. The perioperative clinical data were collected. The incidence of postoperative delirium was assessed using the Confusion Assessment Scale 1-7 days after surgery or 1 day before discharge. The patients were assigned to the training set and the validation set in a ratio of 7∶3 using a simple random sampling method. Multivariate logistic regression was used to identify the risk factors for postoperative delirium, a postoperative delirium risk prediction model was established based on the risk factors, the nomogram was developed, and the receiver operating characteristic (ROC) curve, calibration curve and decision curve were plotted to assess the accuracy of the prediction model. The prediction model was verified using the validation set, and the calibration curve and ROC curve were plotted to assess the predictive performance of the model.Results:A total of 721 patients were finally included, and 108 patients developed postoperative delirium. Older age, high American Society of Anesthesiologists Physical Status classification, history of preoperative hypertension, short years of education, high preoperative Pittsburgh sleep quality index score, high preoperative National Institutes of Health Stroke Scale score, high intraoperative hypothermia, intraoperative hypotension and high postoperative numerical rating scale score were independent risk factors for postoperative delirium ( P<0.05). The area under the ROC curve of the training set prediction model was 0.996, with a sensitivity of 1.000, and specificity of 0.945. The slope of the calibration curve was close to 1, and the predicted risk of postoperative delirium was in good agreement with the actual risk. When the threshold probability of the decision curve was 0-0.9, the net return rate was higher than the null line. Validation set: In the calibration curve of the prediction model, the cohort and calibration curves were close to the ideal line, with an area under the ROC curve of 0.997, sensitivity of 1.000, and specificity of 0.962. Conclusions:Based on age, American Society of Anesthesiologists Physical Status classification, history of preoperative hypertension, years of education, preoperative Pittsburgh sleep quality index score, National Institutes of Health Stroke Scale score, intraoperative hypothermia and hypotension and postoperative numerical rating scale score, the prediction model for postoperative delirium is developed and has a good predictive performance in elderly patients with mild stroke undergoing non-cardiac and non-intracranial surgery.

Objective:To investigate the effects of urinary nickel exposure on insulin resistance, islet function and diabetes risk in adults aged 18 years and above in China.Methods:Based on the China National Human Biomonitoring from 2017 to 2018, a total of 500 diabetes patients were randomly selected as the case group, and the matched euglycemic control were selected by 1∶1 matching ratio. The urinary and venous blood samples of the subjects were collected, and the urinary nickel levels and serum glucose metabolism indexes such as fasting blood glucose and fasting insulin were detected, and the insulin resistance index (HOMA-IR), β cell function index (HOMA-β), and adjusted HOMA-β were calculated by using homeostasis model assessment. A multivariate logistic regression model was used to analyze the association between urinary nickel level and diabetes risk. Multiple linear regression models were used to evaluate the association of urinary nickel level with HOMA-IR, HOMA-β and adjusted HOMA-β.Results:The sex ratio of controls and cases was 1∶1. The multivariate logistic regression model showed that after adjusting for factors such as education level, smoking status, alcohol consumption, rice and meat intakes, family history of diabetes, BMI, total cholesterol level, hypertension, and urinary creatinine, compared with T1 group, the ORs of diabetes risk in the T2 and T3 groups were 1.36 (95% CI: 0.98-1.89) and 1.60 (95% CI: 1.14-2.24), respectively. The multiple linear regression model showed a positive association between urinary nickel levels and the elevated HOMA-IR, the β value of HOMA-IR in the T3 group was 0.12 (95% CI: 0.01-0.25) compared with the T1 group and each one-unit increase in the log-transformed urinary nickel level (2.71 μg/L) was associated with a 0.06 elevation in HOMA-IR (95% CI: 0.02-0.10). Meanwhile, the urinary nickel levels were negative associated with the adjusted HOMA-β, the β value of adjusted HOMA-β in the T3 group were -0.26 compared with the T1 group (95% CI: -0.41- -0.11), and each one-unit increase in the log-transformed urinary nickel level (2.71 μg/L) was associated with a -0.09 decrease in adjusted HOMA-β(95% CI: -0.14- -0.04). Conclusion:Higher urinary nickel level is positively correlated with elevated insulin resistance and diabetes risk while negatively correlated with the function of pancreatic islet β cells in adults in China.

Objective:To examine the association of blood uric acid (UA) and cognitive impairment (CI) among oldest-old adults in China.Methods:Data was collected in 9 longevity areas of China from Healthy Aging and Biomarkers Cohort Study (HABCS) conducted during 2017-2018. Finally,1, 622 elderly aged 80 years and older with complete information on blood UA and cognitive function score were included in this study. Information on demographic characteristics, lifestyle, and health status were collected through questionnaire and physical examination. Venous blood samples of the participants were collected to test blood UA level. Cognitive impairment (CI) was assessed using the Chinese Mini-Mental State Examination (MMSE) according to personal educational level. Generalized Estimating Equations (GEE) model for binary data was used to analyze the association of blood UA and CI, and further compared the associations among different age and body mass index (BMI) groups.Results:Of the 1 622 oldest-old, the mean age was (92.2±8.1) years, 656 (40.4%) were male, the mean level of blood UA was (343.3±86.2) μmol/L, and 482 (29.7%) oldest-old had CI. Compared with the lowest quartile of UA, the risks of CI in the second, third and highest quartiles were gradually reduced, the corresponding ORs and 95% CI were 0.99 (0.71-1.33), 0.87 (0.68-0.94) and 0.69 (0.48-0.85), respectively; and the linear trend test was statistically significant ( P<0.001). Subgroup analysis showed that the effects of higher UA associated with lower risk of CI were stronger in younger oldest-old (aged 80-89 years) and thinner group (BMI<24) ( Pinteraction<0.05). Conclusions:Blood UA was negatively associated with the risk of having CI in the oldest-old among the nine longevity areas of China.

Objective:To investigate the association of blood oxidative stress level with hypertriglyceridemia in the elderly aged 65 years and older in China.Methods:A total of 2 393 participants aged 65 years and older were recruited in 9 longevity areas from Heathy Aging and Biomarkers Cohort Study, during 2017 to 2018. Information on demographics characteristic, life style and health status were collected by questionnaire and physical examination, and venous blood was collected to detect the levels of blood oxidative stress and hypertriglyceridemia. The linear or non-linear association between oxidative stress and hypertriglyceridemia was described by restrictive cubic splines (RCS) fitting multiple linear regression model. The generalized linear mixed effect model was conducted to assess the association between oxidative stress and hypertriglyceridemia.Results:A total of 2 393 participants, mean age was 84.6 years, the youngest was 65 and the oldest was 112, the male was 47.9%(1 145/2 393), the triglyceride level was (1.4±0.8) mmol/L. The hypertriglyceridemia detection rate was 9.99%(239/2 393). The results of multiple linear regression model with restrictive cubic spline fitting showed that MDA level was linear association with triglyceride level; SOD level was nonlinear association with triglyceride level. MDA level had significantly association with hypertriglyceridemia, and the corresponding OR value was 1.063 (95% CI: 1.046,1.081) with 1 nmol/ml increment of blood MDA; SOD level had significantly association with hypertriglyceridemia, and the corresponding OR value was 0.986(95% CI: 0.983,0.989) with 1 U/ml increment of blood SOD. Conclusion:Among the elderly aged 65 and older in 9 longevity areas in China, MDA and SOD levels were associated with the risk of hypertriglyceridemia.

Objective:To investigate the relationship between the neutrophil-to-lymphocyte ratio (NLR) and the risk of depression symptoms among older adults aged 65 and above in 9 longevity areas of China.Methods:Data was collected in 9 longevity areas of China from Healthy Aging and Biomarkers Cohort Study (HABCS) conducted between 2017 and 2018. Finally,2018 elderly aged 65 years and above with complete information on neutrophil count, lymphocyte count and depressive symptoms were included in this study. Information on demographic characteristics, lifestyle, and health status was collected through questionnaire and physical examination. Complete blood counts which included lymphocytes and neutrophils were obtained by testing venous blood samples. Participants were divided into four groups by the quartile of NLR level, i.e. Q1, Q2, Q3, Q4. Logistic regression model was applied to analyze the association of NLR with depression symptoms. Results:Among 2 018 older adults, the mean(±SD) age was 82.6(±10.73), 1 032(51.14%) were male, 390(19.33%) were detected with depressive symptoms. Compared with participants of NLR in the 1 st quartile, the OR(95% CI) of risk for depressive symptoms was 1.47 (0.99, 2.19), 1.67 (1.13, 2.47) and 1.95 (1.32, 2.89), respectively. Conclusion:Increased NLR level is significantly related to depressive symptoms among elderly aged 65 years and above in 9 longevity areas in China.

Objective:To investigate the association between blood lead concentrations and cognition impairment among Chinese older adults aged 65 or over.Method:Data was collected in 9 longevity areas from Heathy Aging and Biomarkers Cohort Study between 2017 and 2018. This study included 1 684 elderly aged 65 years and older. Information about demographic characteristics, socioeconomic factors, health status and cognitive function score of respondents were collected by questionnaire survey and physical examination. Venous blood of the subjects was collected to detect the blood lead concentration. Subjects were stratified into four groups ( Q 1- Q 4) by quartile of blood lead concentration. Multivariate logistic regression model was used to analyze the association between blood lead concentration and cognitive impairment. The linear or non-linear association between blood lead concentration and cognitive impairment were described by restrictive cubic splines (RCS). Results:Among the 1 684 respondents, 843 (50.1%) were female and 191 (11.3%) suffered from cognition impairment. After adjusting for confounding factors, the OR value and 95% CI of cognition impairment was 1.05 (1.01-1.10) for every 10 μg/L increase in blood lead concentration in elderly; Compared with the elderly in Q 1, the elderly with higher blood lead concentration had an increased risk of cognitive impairment. The OR value and 95% CIof Q2, Q3 and Q4 groups were 1.19 (0.69-2.05), 1.45 (0.84-2.51) and 1.92 (1.13-3.27), respectively. Conclusion:Higher blood lead concentration is associated with cognitive impairment among the elderly aged 65 years and older in 9 longevity areas in China.