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Abstract Background Sarcopenia is an age-related clinical syndrome, which is associated with numerous adverse outcomes among older adults. The relationship between sarcopenia and activities of daily living (ADL) disability has been studied in China, but these findings usually focused on a single time point. The patterns of ADL can change over time and vary among individuals. Therefore, it is necessary to explore the association between sarcopenia and trajectories of ADL disability. Methods According to Asian Working Group for Sarcopenia (AWGS) 2019 criteria, muscle mass, muscle strength, and physical performance measurements were measured to diagnose sarcopenia. A six-item ADL score was used to measure ADL disability, and trajectories of ADL disability were identified by the latent class trajectory modelling (LCTM). Multiple logistic regression models were performed to examine the association between sarcopenia and trajectories of ADL disability. Results Among 9113 middle-aged and older adults, three trajectories of ADL disability were determined according to changes in ADL score during follow-up, including a mild-high trajectory (n = 648, 7.11%), followed by the low-mild trajectory (n = 3120, 34.24%) and low-low trajectory (n = 5345, 58.65%). After adjustment for covariates, severe sarcopenia was significantly associated with higher risks of being in the mild-high trajectory group (OR = 3.31, 95%CI: 2.10–5.22) and the low-mild trajectory group (OR = 1.44, 95%CI: 1.05–1.98), compared with the low-low trajectory group. This association was still observed when stratified by age and gender. In addition, participants with sarcopenic obesity were associated with a higher risk of ADL disability (OR = 3.99; 95% CI: 2.50–6.09). Conclusions Among the middle-aged and older Chinese adults, sarcopenia and sarcopenic obesity were both associated with persistent higher trajectories of ADL disability. It suggested that early interventions to sarcopenia and sarcopenic obesity among the middle-aged and older adults may reduce the progression of ADL disability.

Abstract Background Beak morphology exhibits considerable adaptive plasticity in birds, which results in highly varied or specialized forms in response to variations in ecology and life history. As the only parid species endemic to the Qinghai-Tibet Plateau, the Ground Tit (Parus humilis) has evolved a distinctly long and curved beak from other parids. An integration of morphometrics, phylogenetics, transcriptomics and embryology allows us to address the evolutionary and developmental mechanisms of the adaptive beak structure observed in the Ground Tit. Results A morphometric approach quantified that the Ground Tit has a comparatively longer and more decurved upper beaks than other parids. We estimated that the ancestor of the Ground Tit likely had a short straight upper beak similar to most current recognized parid species using an ancestral state reconstruction. This morphological specialization is considered an adaptation to its ground-oriented behavior on the high plateau. To identify genetic mechanisms behind this adaptive change, a comparative transcriptomic analysis was applied between the Ground Tit and its closely related species, the Great Tit (Parus major). We detected that 623 genes were significantly differentially expressed in embryonic upper beaks between the two species, 17 of which were functionally annotated to correlate with bone development and morphogenesis, although genes related to bone development were not found to undergo accelerated evolution in the Ground Tit. RT-qPCR validation confirmed differential expression of five out of eight genes that were selected from the 17 genes. Subsequent functional assays in chicken embryos demonstrated that two of these genes, FGF13 and ITGB3, may affect beak morphology by modulating levels of osteoblasts and osteoclasts. Conclusions Our results provide preliminary evidence that development of the long decurved beak of the Ground Tit is likely regulated by transcriptional activities of multiple genes coordinating osteoblasts and osteoclasts. The integration of multiple approaches employed here sheds light on ecological and genetic mechanisms in the evolution of avian morphology.