TNNC1 and sarcopenia: Transcriptomic analysis identified BDNF, JAK2, RhoC, Myh6, Stat5a, and Tnnc1 as core target genes that may mediate the effects of different exercise intervention stimuli through the JAK-STAT, cGMP-PKG, and Rap1 pathways to improve the skeletal muscle phenotype of sarcopenia.