A 12-week supervised concurrent resistance training plus HIIT programme in 38 adults aged 55–70 years produced surprisingly modest skeletal muscle transcriptional changes. RNA-sequencing of vastus lateralis biopsies revealed only seven transcripts exceeding both FDR significance and a log2 fold-change threshold of 1.0, including upregulation of CLLU1 (log2FC = 3.10) and PRND (log2FC = 2.60), and downregulation of the fast-twitch myosin heavy chain gene MYH1 (log2FC = −1.3). Pathway-level enrichment was absent, and polyphenol supplementation (vs. placebo) produced no coherent transcriptional signature beyond baseline HMOX1 elevation.
The finding that 12 weeks of structured concurrent training in middle-aged and older adults fails to generate broad, coordinated transcriptional remodelling is both humbling and instructive. Prior transcriptomic studies of pure resistance training in younger cohorts routinely identify hundreds of differentially expressed genes across myogenic, inflammatory, and metabolic pathways. The muted response here likely reflects the heterogeneity of ageing muscle, high inter-individual variability, and a relatively modest sample size of 38 — underpowered for transcriptomics. The MYH1 downregulation suggests a shift away from fast-twitch fibre phenotype, consistent with ageing physiology rather than adaptation reversal. The polyphenol null result challenges optimistic claims about resveratrol- or quercetin-class compounds amplifying exercise adaptation at the gene-expression level. Practically, this trial reinforces that functional gains from exercise in older adults may be mediated more by post-translational, protein-level, or neural adaptations than by transcriptional reprogramming — and that polyphenol supplements offer no measurable molecular synergy with training in this population.