20.500.12556/DiRROS-25205 Previous short-term disuse dictates muscle geneexpression and physiological adaptations to subsequentresistance exercise Short-term unloading experienced following injury or hospitalisation induces muscle atrophy and weakness. The effects of exercise following unloading have been scarcely investigated. We investigated the functional and molecular adaptations to a resistance training (RT) programme following short-term unloading. Eleven males (22.09 ± 2.91 years) underwent 10 days of unilateral lower limb suspension (ULLS) followed by 21 days of knee extensor RT (three times/week). Data collection occurred at Baseline (LS0), after ULLS (LS10) and at active recovery (AR21). Knee extensor maximum voluntary contraction (MVC) was evaluated. Quadriceps volume was estimated by ultrasonography. Muscle fibre cross-sectional area, fibre type distribution, glycogen content and succinate dehydrogenase (SDH) activity were measured from vastus lateralis biopsies. Mitochondrial-related proteins were quantified by western blot and transcriptional responses were assessed by RNA sequencing. Following ULLS, quadriceps volume and MVC decreased significantly (3.7%, P < 0.05; 29.3%, P < 0.001). At AR21 (vs. LS10), MVC was fully restored (42%) and quadriceps volume increased markedly (18.6%, P < 0.001). Glycogen content and whole-body water increased at AR21 (14%, P < 0.001; 3.1%, P < 0.05). We observed a marked increase in fibre type I at AR21 (38%, P < 0.05). SDH immunoreactivity increased significantly after exercise (20%, P < 0.001). Mitochondrial fusion (MFN1, MFN2 and OPA1) and fission (DRP1) proteins were markedly increased by RT, and the most differentially expressed genes belonged to oxidative phosphorylation pathways. In contrast with what is usually observed after RT, oxidative metabolism, slow fibre type and mitochondrial dynamics were enhanced beyond expected. We propose that prior exposure to short-term muscle unloading may drive the nature of molecular adaptations to subsequent RT. exercise physiology gene expression muscle adaptation muscle atrophy musle physiology muscle plasticity resistance training unloading responses fiziologija vadbe izražanje genov prilagoditev mišic atrofičnost mišic mišična fiziologija mišična plastičnost trening z uporom odzivi na razbremenitev true false true Angleški jezik Slovenski jezik © 2025 The Author(s) Neznano 2026-01-13 15:14:14 2026-01-13 15:14:14 2026-01-14 03:53:46 0000-00-00 00:00:00 2025 0 0 str. 3725-3753 iss. 13 Vol. 603 2025 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 2025-01-01 612 0022-3751 10.1113/JP287003 264568067 16-01-13-Narici-264568067.pdf 16-01-13-Narici-264568067.pdf 1 3ABC83FBD05E08468CE195E515D78351 7629e73a78cc4e1cb29a8dc201ff6d9e58c3d3cdf5493e62071ea2e545b33fe3 3ba9ab39-f08a-11f0-94a7-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=38022 https://physoc.onlinelibrary.wiley.com/doi/10.1113/JP287003 1 25202db9-f08a-11f0-94a7-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=38021 Znanstveno-raziskovalno središče Koper / Centro di Ricerche Scientifiche Capodistria 0 0 0