ObjectiveTo investigate the association of physical activity and balance ability with disability, and to further examine the mediating role of balance ability in the relationship between physical activity and disability. MethodsBased on data from 2021 to 2023 National Health and Nutrition Examination Survey (NHANES) cycle, a multivariable Logistic regression model was constructed to evaluate the independent association of physical activity and balance ability with disability, with covariates adjusted in four steps. An interaction model was further developed to assess the multiplicative interaction between physical activity and balance ability. Mediation analysis was performed using the Baron and Kenny three-step approach to examine the mediating role of balance ability, and the proportion of the mediation effect was calculated. The significance of the mediation effect was assessed using the Delta method, and robustness was verified through the Bootstrap method with a fixed random seed. Multiple sensitivity analyses were conducted to ensure the stability of the results. ResultsA total of 3 902 participants were included, with a prevalence of disability of 17.7%. Multivariable regression analysis showed that, after adjusting for all covariates, both light-intensity physical activity (LIPA) (OR = 0.489, 95%CI 0.380 to 0.629, P < 0.001) and high-intensity physical activity (HIPA) (OR = 0.493, 95%CI 0.371 to 0.656, P < 0.001) were significantly associated with a reduced risk of disability, whereas impaired balance ability was significantly associated with an increased risk (OR = 1.579, 95%CI 1.266 to 1.970, P < 0.001). The interaction effect analysis showed that the interaction between physical activity and balance ability were not significant (P > 0.05), however, the main effect of LIPA remained robust (β = -0.597, SE = 0.221, OR = 0.550, P = 0.007), while impaired balance ability was significantly associated with an increased risk of disability (β = 0.577, SE = 0.231, OR = 1.780, P = 0.012). The mediation analysis further indicated that balance ability played a robust mediating role in the association between LIPA and disability, with a mediation proportion of 21.1%. The indirect effect (a × b) was statistically significant (P < 0.001), and the 95% confidence intervals derived from the bootstrap method did not include zero. ConclusionPhysical activity and balance ability are significantly associated with disability, and balance ability may mediate the relationship between physical activity and disability, highlighting its potential value in disability risk assessment and intervention strategies.

OBJECTIVE:A great deal of evidence indicates that regular exercise can improve the health status of elderly individuals,including reducing overall and abdominal fat levels,increasing muscle mass and bone mineral density of the limbs,thereby preventing or delaying the onset of sarcopenia and its comorbidities.This study aims to determine the most reliable type,duration,and intensity of exercise interventions through meta-analysis to prevent,delay,and alleviate sarcopenia and its comorbidities in elderly individuals.METHODS:Randomized controlled trials examining the effects of exercise interventions on elderly individuals with sarcopenia and its comorbidities were searched in the PubMed,Embase,Web of Science,Cochrane Library,CNKI,and WanFang databases.The Cochrane Risk of Bias Tool was used to assess the quality of the included studies,and RevMan 5.3 software was employed for meta-analysis.Subgroup analyses were conducted to explore the effects of different exercise intervention protocols on various outcome measures.In addition,Stata 16.0 software was used to perform sensitivity analysis to assess the stability of the results,and funnel plots and Egger's test were employed to evaluate publication bias,ensuring the comprehensiveness and reliability of the results.RESULTS:(1)Sixteen studies involving 861 patients with sarcopenia and its comorbidities were included.(2)The meta-analysis results indicated that,compared with the control group,exercise significantly improved grip strength,knee muscle strength,appendicular skeletal muscle mass,skeletal muscle index,Timed Up and Go test results,gait speed,and insulin-like growth factor 1 levels(P＜0.05).However,the effect of exercise intervention on the sit-to-stand test was not significantly improved(P＞0.05).(3)Based on the results of subgroup analysis,it is recommended that elderly patients with sarcopenia and its comorbidities engage in exercise at least three times per week,with each session lasting no more than 30 minutes or exceeding 45 minutes,for at least 12 weeks.The exercise protocol should be flexibly adjusted according to the patient's health status and individual needs.CONCLUSION:Exercise interventions significantly improve muscle mass,muscle strength,physical function,and insulin-like growth factor 1 levels in elderly individuals with sarcopenia and its comorbidities,thereby enhancing their quality of life.However,further research is needed to validate these findings and optimize specific intervention protocols.

OBJECTIVE:A great deal of evidence indicates that regular exercise can improve the health status of elderly individuals,including reducing overall and abdominal fat levels,increasing muscle mass and bone mineral density of the limbs,thereby preventing or delaying the onset of sarcopenia and its comorbidities.This study aims to determine the most reliable type,duration,and intensity of exercise interventions through meta-analysis to prevent,delay,and alleviate sarcopenia and its comorbidities in elderly individuals.METHODS:Randomized controlled trials examining the effects of exercise interventions on elderly individuals with sarcopenia and its comorbidities were searched in the PubMed,Embase,Web of Science,Cochrane Library,CNKI,and WanFang databases.The Cochrane Risk of Bias Tool was used to assess the quality of the included studies,and RevMan 5.3 software was employed for meta-analysis.Subgroup analyses were conducted to explore the effects of different exercise intervention protocols on various outcome measures.In addition,Stata 16.0 software was used to perform sensitivity analysis to assess the stability of the results,and funnel plots and Egger's test were employed to evaluate publication bias,ensuring the comprehensiveness and reliability of the results.RESULTS:(1)Sixteen studies involving 861 patients with sarcopenia and its comorbidities were included.(2)The meta-analysis results indicated that,compared with the control group,exercise significantly improved grip strength,knee muscle strength,appendicular skeletal muscle mass,skeletal muscle index,Timed Up and Go test results,gait speed,and insulin-like growth factor 1 levels(P＜0.05).However,the effect of exercise intervention on the sit-to-stand test was not significantly improved(P＞0.05).(3)Based on the results of subgroup analysis,it is recommended that elderly patients with sarcopenia and its comorbidities engage in exercise at least three times per week,with each session lasting no more than 30 minutes or exceeding 45 minutes,for at least 12 weeks.The exercise protocol should be flexibly adjusted according to the patient's health status and individual needs.CONCLUSION:Exercise interventions significantly improve muscle mass,muscle strength,physical function,and insulin-like growth factor 1 levels in elderly individuals with sarcopenia and its comorbidities,thereby enhancing their quality of life.However,further research is needed to validate these findings and optimize specific intervention protocols.

Objective:To propose a functional method for locating the shoulder joint center of rotation aimed at rapid estimation of the upper limb reachable domain envelope, thereby informing ergonomic design and task optimization.Methods:In March 2024, shoulder kinematics during gait were recorded from ten adults using a three-dimensional motion-capture system. Assuming the existence of a point near the glenohumeral joint that maintains a fixed spatial relationship to the humerus and the acromion, we estimated both static and dynamic centers of rotation. Localization accuracy was quantified by the standard deviation of distance residuals to upper-arm markers. Upper-limb joint angles and anthropometric parameters were modeled via regression; combined with maximal joint ranges of motion, these were used to infer the reachable domain envelope.Results:The static center of rotation was located approximately twenty-two millimeters medial to the acromial landmark in the coronal plane and thirty-seven millimeters inferior to it. The standard deviation of the residuals for the distances from the dynamic shoulder joint center of rotation to upper-arm markers averaged 1.02 mm, which was 47.42% lower than that of the static center of rotation and 66.56% lower than that of the acromion. Moreover, the trajectory of this dynamic center showed a strong correlation with upper-limb joint angles ( R2>0.7) . Conclusion:The proposed method enables rapid and accurate estimation of the upper limb reachable domain envelope to support ergonomic design and may help reduce the risk of work-related musculoskeletal disorders.

BACKGROUND:Surface electromyography has been extensively utilized for monitoring muscle fatigue. However,traditional electromyographic metrics typically focus on individual muscles and fail to assess the variations in a muscle group during the fatigue process. OBJECTIVE:To establish a muscle functional network to extract complex network parameters and investigate the topological property changes of the muscle functional network under different levels of fatigue,aiming to provide theoretical and methodological foundations for fatigue monitoring and prevention. METHODS:Eleven participants performed single-leg leg press exercise at 50％ of one-repetition maximum until exhaustion. Simultaneously,electromyographic signals of seven muscles (rectus femoris,vastus lateralis,vastus medialis,biceps femoris,tibialis anterior,lateral gastrocnemius,and medial gastrocnemius),electrocardiographic signals,and Borg CR-10 scale scores were collected. The Borg CR-10 scale was used to categorize three fatigue stages:mild,moderate,and severe. Heart rate and heart rate variability were calculated to validate the effective division of fatigue stages. Using the coherence of muscle signals,a muscle functional network was constructed with the seven muscles as nodes,and four complex network parameters (clustering coefficient,average weighted degree,global efficiency,and eigenvector centrality) were extracted. Additionally,four electromyographic indices (root mean square,median frequency,instantaneous mean frequency,and co-activation ratio) were extracted and compared under the three levels of fatigue. RESULTS AND CONCLUSION:(1) Differences in heart rate and heart rate variability were observed across three fatigue stages,indicating the effectiveness of fatigue stage delineation. (2) Electromyographic indicators for different muscles under three levels of fatigue:root mean square and co-activation ratio showed no differences;however,median frequency exhibited robust fatigue trends in vastus lateralis,vastus medialis,and biceps femoris,while instantaneous mean frequency demonstrated robust fatigue trends in rectus femoris,vastus lateralis,vastus medialis,and biceps femoris. Instantaneous mean frequency outperformed median frequency and root mean square,yet all three indicators showed robust trends only for the major working muscle groups,unaffected by fatigue factors,unlike the co-activation ratio. (3) The connectivity strength between vastus lateralis and vastus medialis,vastus lateralis and biceps femoris,vastus lateralis and gastrocnemius medialis,and vastus medialis and biceps femoris gradually increased,showing significant differences in average weighted degree,clustering coefficient,and global efficiency post-fatigue,significantly correlated with fatigue levels. To conclude,changes in connectivity strength reflect the synergy and complementarity among muscles during fatigue. Clustering coefficient,average weighted degree,and global efficiency serve as fatigue markers reflecting overall muscle changes.

Objective:To evaluate the association between body temperature and duration of mechanical ventilation in the intensive care unit (ICU) among patients after coronary artery bypass grafting (CABG).Methods:Clinical data from patients, aged >18 yr, undergoing primary isolated CABG, between 2008 and 2019, were extracted from the Medical Information Mart for Intensive Care Ⅳ version 2.0 database. Participants were stratified into 3 groups based on the mean body temperature in ICU: hypothermia group (<36.0 ℃), normothermia group (36.0 ℃ ≤ temperature <37.3 ℃), and hyperthermia group (≥37.3 ℃). Multivariable linear regression and linear curve fitting were performed to assess the association between body temperature and duration of mechanical ventilation.Results:A total of 4, 588 patients were finally included in the statistical analysis, including 133 cases in hypothermia group, 4, 177 cases in normothermia group and 278 cases in hyperthermia group. The duration of mechanical ventilation was significantly prolonged in both hypothermia and hyperthermia groups compared with normothermia group ( P<0.05). The results of multivariable linear regression demonstrated that each 1 ℃ increase in body temperature was associated with a 2.43 h reduction in the duration of mechanical ventilation in hypothermia group ( P<0.001), and each 1 ℃ temperature elevation corresponded to a non-significant reduction of 0.12 h in hyperthermia group ( P=0.851). The results of linear curve fitting revealed a U-shaped relationship between body temperature and duration of mechanical ventilation, and an inflection point was identified at 36.71 ℃, with duration of mechanical ventilation prolonged with temperatures either below or above this threshold ( P<0.05). Conclusions:Hypothermia during ICU stay following CABG may lead to prolonged mechanical ventilation in patients.

Objective:To evaluate the efficacy of the flipped classroom combined with 3D body anatomy software in the teaching of ultrasound-guided transversus thoracic muscle plane block.Methods:In this randomized controlled trial, 100 second-year resident physicians from the Department of Anesthesiology and Perioperative Medicine at our hospital, male or female, aged 22-26 yr, who rotated during January 2023 to January 2025, were selected and divided into 2 groups ( n=50 each) using a table of random numbers: experimental group and control group. Experimental group employed the teaching model of flipped classroom combined with 3D body anatomy software, while control group used the traditional teaching model. The scores of theoretical assessment, accuracy rate of ultrasound image identification, scores of procedural skills, success rates of clinical procedure, teaching satisfaction, and success rates of clinical translation after 1 month follow-up were compared between two groups. Results:Compared with control group, the scores of theoretical assessment, accuracy rate of ultrasound image identification, scores of procedural skills, success rates of clinical procedure, teaching satisfaction, and success rates of clinical translation after 1 month follow-up were significantly increased in experimental group ( P<0.05). Conclusions:The combination of flipped classroom and 3D body anatomy software is more effective than the traditional teaching methods when used for teaching of ultrasound-guided transversus thoracic muscle plane block.

Objective:To propose a functional method for locating the shoulder joint center of rotation aimed at rapid estimation of the upper limb reachable domain envelope, thereby informing ergonomic design and task optimization.Methods:In March 2024, shoulder kinematics during gait were recorded from ten adults using a three-dimensional motion-capture system. Assuming the existence of a point near the glenohumeral joint that maintains a fixed spatial relationship to the humerus and the acromion, we estimated both static and dynamic centers of rotation. Localization accuracy was quantified by the standard deviation of distance residuals to upper-arm markers. Upper-limb joint angles and anthropometric parameters were modeled via regression; combined with maximal joint ranges of motion, these were used to infer the reachable domain envelope.Results:The static center of rotation was located approximately twenty-two millimeters medial to the acromial landmark in the coronal plane and thirty-seven millimeters inferior to it. The standard deviation of the residuals for the distances from the dynamic shoulder joint center of rotation to upper-arm markers averaged 1.02 mm, which was 47.42% lower than that of the static center of rotation and 66.56% lower than that of the acromion. Moreover, the trajectory of this dynamic center showed a strong correlation with upper-limb joint angles ( R2>0.7) . Conclusion:The proposed method enables rapid and accurate estimation of the upper limb reachable domain envelope to support ergonomic design and may help reduce the risk of work-related musculoskeletal disorders.

Objective:To evaluate the association between body temperature and duration of mechanical ventilation in the intensive care unit (ICU) among patients after coronary artery bypass grafting (CABG).Methods:Clinical data from patients, aged >18 yr, undergoing primary isolated CABG, between 2008 and 2019, were extracted from the Medical Information Mart for Intensive Care Ⅳ version 2.0 database. Participants were stratified into 3 groups based on the mean body temperature in ICU: hypothermia group (<36.0 ℃), normothermia group (36.0 ℃ ≤ temperature <37.3 ℃), and hyperthermia group (≥37.3 ℃). Multivariable linear regression and linear curve fitting were performed to assess the association between body temperature and duration of mechanical ventilation.Results:A total of 4, 588 patients were finally included in the statistical analysis, including 133 cases in hypothermia group, 4, 177 cases in normothermia group and 278 cases in hyperthermia group. The duration of mechanical ventilation was significantly prolonged in both hypothermia and hyperthermia groups compared with normothermia group ( P<0.05). The results of multivariable linear regression demonstrated that each 1 ℃ increase in body temperature was associated with a 2.43 h reduction in the duration of mechanical ventilation in hypothermia group ( P<0.001), and each 1 ℃ temperature elevation corresponded to a non-significant reduction of 0.12 h in hyperthermia group ( P=0.851). The results of linear curve fitting revealed a U-shaped relationship between body temperature and duration of mechanical ventilation, and an inflection point was identified at 36.71 ℃, with duration of mechanical ventilation prolonged with temperatures either below or above this threshold ( P<0.05). Conclusions:Hypothermia during ICU stay following CABG may lead to prolonged mechanical ventilation in patients.

Objective:To evaluate the efficacy of the flipped classroom combined with 3D body anatomy software in the teaching of ultrasound-guided transversus thoracic muscle plane block.Methods:In this randomized controlled trial, 100 second-year resident physicians from the Department of Anesthesiology and Perioperative Medicine at our hospital, male or female, aged 22-26 yr, who rotated during January 2023 to January 2025, were selected and divided into 2 groups ( n=50 each) using a table of random numbers: experimental group and control group. Experimental group employed the teaching model of flipped classroom combined with 3D body anatomy software, while control group used the traditional teaching model. The scores of theoretical assessment, accuracy rate of ultrasound image identification, scores of procedural skills, success rates of clinical procedure, teaching satisfaction, and success rates of clinical translation after 1 month follow-up were compared between two groups. Results:Compared with control group, the scores of theoretical assessment, accuracy rate of ultrasound image identification, scores of procedural skills, success rates of clinical procedure, teaching satisfaction, and success rates of clinical translation after 1 month follow-up were significantly increased in experimental group ( P<0.05). Conclusions:The combination of flipped classroom and 3D body anatomy software is more effective than the traditional teaching methods when used for teaching of ultrasound-guided transversus thoracic muscle plane block.