Fig. 2.

The effects of high-intensity interval training (HIIT) on mitonuclear imbalance, UPRmt, and mitochondrial metabolism in skeletal muscle of aged mice. a Figure represents the 4-week HIIT protocol designed for aged animals. b Exercise induces mitonuclear imbalance and improves the gene expression (c) and protein content (d) of UPRmt markers. RT-qPCR and western blot analyses were also performed to evaluate: e citrate synthase and (f–g) markers of mitochondrial biogenesis. h Total body mass (n = 9). Results achieved during grip strength (i) and treadmill running tests (j–k). Each point represents a sample, varying according to the experiment performed. Statistical significance was fixed at *p < 0.05