The effects of the “living high–training low” model on key proteins involved in cellular aerobic and anaerobic metabolism in male <scp>C</scp> 57 <scp>BL</scp> /6 <scp>J</scp> mice

This study aimed to investigate the effects of the "living high-training low" (LHTL) model, in which mice were housed under hypoxic conditions but trained in normoxia to maintain training quality. We analyzed key proteins involved in cellular metabolism and oxidative stress, including hypoxia-inducible factor 1α (HIF-1α), peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α), and oxidation resistance protein 1 (OXR1). Forty male isogenic C57BL/6J mice were divided into nontrained (N) and trained (T) groups living in normoxic (NOR) or hypoxic (HYP) environments. HYP mice were housed 18 h/day for 8 weeks in a normobaric tent supplied with oxygen-depleted air (FiO₂ = 14.5%). Animal handling, including training, was conducted in normoxia (FiO₂ = 19.5%). Training occurred 5 times/week (40 min/session) at ~80% of individual critical velocity. All mice were euthanized to extract the soleus, white gastrocnemius, and hypothalamus for protein analysis. Compared with training alone, LHTL did not lead to significantly greater HIF-1α, PGC-1α, or OXR1 expression across tissues; however, induced behavioral changes-such as reduced spontaneous physical activity and diminished ability to complete training-may indicate that the demands of the LHTL model were not trivial.