Introduction: A Growing Challenge in Shanghai’s Aging Population
Population aging is reshaping healthcare needs worldwide, and Shanghai stands at the forefront of this demographic shift. This cross-sectional study investigates how common sarcopenia and sarcopenic obesity (SO) are among adults aged 60 and older in Shanghai, and which body composition and biochemical indicators best predict risk. By identifying independent factors, the research aims to support early detection and targeted interventions to preserve muscle health and overall vitality in an urban, high-income setting.
What the Study Measured
Participants aged ≥60 were recruited from a Shanghai health examination center between July and December 2023. Researchers gathered demographic data, anthropometrics, laboratory markers, and body composition using bioelectrical impedance analysis (BIA). Sarcopenia diagnosis followed the 2019 Asian Working Group for Sarcopenia (AWGS) criteria, incorporating muscle mass (ASMI), grip strength, and gait speed. Obesity was defined by fat percentage per World Health Organization standards. Four phenotypes emerged: sarcopenic obesity (SO), sarcopenia without obesity, obesity without sarcopenia, and non-sarcopenia/non-obesity.
Key Findings: Prevalence and Sex Differences
Among 700 community-dwelling older adults, the overall prevalence of sarcopenia was 13.6%, and SO stood at 6.9%. Those with SO were the oldest group, averaging around 70.5 years, with pronounced sex disparities. The data revealed notable sex differences in sarcopenia and body composition: men with sarcopenia tended to have higher absolute muscle mass and albumin but lower fat percentages compared with women, while women showed greater fat infiltration into muscles (higher body fat percentage), which may contribute to functional decline despite differences in muscle mass.
Body Composition and Biochemical Predictors
Visceral fat area (VFA) emerged as a critical independent predictor of sarcopenia. Each 1 cm² increase in VFA raised sarcopenia risk by about 14%. Appendicular muscle mass, reflected by ASMI, was a central quantitative factor; lower ASMI strongly predicted sarcopenia (high odds ratio). These findings underscore the muscle-fat balance theory: aging, coupled with visceral adiposity, accelerates muscle loss and functional impairment. Nutritional markers such as albumin also featured in sex-specific comparisons, hinting at broader metabolic health influences on muscle maintenance.
Age, Sex, and Lifestyle Influences
Age remained a dominant determinant: individuals aged 79 and above had markedly higher odds of sarcopenia. While univariate analyses hinted at smoking and drinking as potential risks, these associations did not hold after multivariate adjustment, suggesting that once age, adiposity, and muscle mass are considered, lifestyle factors alone may have a weaker direct link in this urban cohort. The study’s urban Shanghai context—characterized by higher socioeconomic status and access to nutrition—highlights how environment and healthcare access can shape sarcopenia risk and detection, even as biological aging persists.
Sex-Specific Implications for Prevention and Screening
The authors emphasize sex-specific screening to optimize prevention: older men may benefit from strategies focused on sustaining muscle mass, while addressing fat distribution and sarcopenic risk in women could be particularly important given higher fat infiltration. Clinicians should consider comprehensive assessments that combine ASMI, grip strength, gait speed, and visceral adiposity to identify those at greatest risk for sarcopenia and SO.
Clinical and Public Health Relevance
As China’s rapidly aging population faces rising chronic diseases and healthcare costs, early detection of sarcopenia and SO is crucial. This Shanghai-centered study provides fresh multicenter data to guide clinical screening protocols and community-based interventions aimed at preserving muscle health, preventing disability, and reducing hospitalizations among older adults. Tailored approaches that integrate nutrition, physical activity, and monitoring of visceral fat may offer the most promise for urban seniors.
Limitations and Future Directions
Limitations include the cross-sectional design, which constrains causal inferences, and the single-center sampling frame, which may limit generalizability to all of Shanghai. Future longitudinal studies with larger, more diverse samples are needed to validate predictors of SO and to examine how interventions influence trajectories of muscle mass and function over time.
Conclusion
This study is among the first to quantify sarcopenia and SO prevalence in Shanghai’s older adults and to link these conditions with precise body composition and visceral adiposity measures. The findings advocate for early, sex-sensitive screening and targeted prevention to safeguard mobility, independence, and quality of life in China’s aging urban population.
