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High‐intensity interval training changes the expression of muscle RING‐finger protein‐1 and muscle atrophy F‐box proteins and proteins involved in the mechanistic target of rapamycin pathway and autophagy in rat skeletal muscle

This study aimed to investigate the impact of high‐intensity interval training (HIIT) on the proteins involved in protein synthesis, the ubiquitin–proteasome system (UPS) and autophagy in skeletal muscle of middle‐aged rats. Nine‐ month‐old male Wistar rats (n = 56) were randomly divided into three groups: a control (C) group, a moderate‐intensity continuous training (MICT) group and a HIIT group. Rats in the training groups ran on treadmills 5 days per week for 8 weeks. The MICT group ran for 50 min at 60% urn:x- wiley:09580670:media:eph12562:eph12562-math- 0001, while the HIIT group ran for 3 min at 80% of urn:x- wiley:09580670:media:eph12562:eph12562-math- 0002 six times separated by 3‐min periods at 40% urn:x- wiley:09580670:media:eph12562:eph12562-math- 0003. Aerobic endurance, number of autophagosomes and expression of proteins involved in protein synthesis and degradation in the soleus muscle were measured at three time points: before training, after 4 weeks and after 8 weeks of training. Compared to the C group, HIIT and MICT increased the expression of phosphorylated mechanistic target of rapamycin (mTOR) after 8 weeks (P < 0.05 and P < 0.01, respectively). HIIT increased the expression of muscle RING‐finger protein‐1 (MuRF‐1) after 4 weeks (P < 0.01), and decreased its expression after 8 weeks (P < 0.01). Both HIIT and MICT decreased the expression of muscle atrophy F‐box (MAFbx) after 4 weeks (P < 0.05). HIIT improved the expression of microtubule‐associated protein 1A/1B‐light chain 3 (LC3)‐II (P < 0.05), and decreased the P62 content (P < 0.01) after 4 weeks. The LC3II/LC3I ratio was increased after 8 weeks (P < 0.01). This study demonstrated that HIIT could activate the mTOR pathway, alter the expression of MuRF‐1 and MAFbx proteins, and enhance autophagic flux in soleus muscle of middle‐aged rat

HIIT training ; RING‐finger protein‐1 ; muscle atrophy ; skeletal muscle

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