Sprint interval exercise disrupts mitochondrial ultrastructure driving a unique mitochondrial stress response and remodelling in men
Javier Botella, Enrico Perri, Nikeisha J. Caruana, Sandra López-Calcerrada, Michele Brischigliaro, Nicholas A. Jamnick, Viola Oorschot, Nicholas J. Saner, Javier Díaz‐Lara, Dale F. Taylor, Andrew Garnham, Erika Fernández‐Vizarra, Cristina Ugalde, Georg Ramm, David A. Stroud, Michael Lazarou, David J. Bishop
Abstract
Exercise is a key lifestyle intervention for mitochondrial health, yet the molecular mechanisms by which different exercise prescriptions regulate mitochondrial remodeling remain unclear. We conducted an open-label counterbalanced randomized controlled trial (ACTRN12617001105336) and observed that sprint-interval exercise (SIE; n = 14), compared to moderate-intensity continuous exercise (MICE; n = 14), induces a mitochondrial stress signature and unfolded protein response (UPRmt). SIE triggers morphological and structural mitochondrial alterations along with activation of the integrated stress response (ISR) and mitochondrial quality control (MQC) pathways. Following eight weeks of training, moderate-intensity continuous training (MICT) increases mitochondrial content, complex I activity, and displays an enrichment of tricarboxylic acid (TCA) cycle and oxidative phosphorylation (OXPHOS) proteins, while sprint-interval training (SIT) improves respiratory function and upregulates pathways involved in 1-carbon metabolism and protein quality control. We identify COX7A2L accumulating in III2 + IV1 supercomplexes only after SIT. These findings elucidate how exercise intensity shapes mitochondrial remodeling, informing tailored exercise prescriptions. Here the authors report a that sprint interval exercise triggers mitochondrial stress and quality control in skeletal muscle in young healthy men, promoting enhanced mitochondrial function and a remodelling after 8 weeks of training.