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Updated: Jun 27, 2026

Supramaximal Intensity Hypoxic Exercise and Vascular Function Assessment in Mice
Published on: March 15, 2019
Slow and fast locomotor muscle adaptations to sustained intermittent hypoxaemia
Lise Paprzycki1, Vincianne Jenart2, Alexandre Legrand2
1Laboratory of Respiratory Physiology, Pathophysiology and Rehabilitation, Research Institute for Health Sciences and Technology, University of Mons, Mons, Belgium; Cell Biology Research Unit (URBC), Namur Research Institute for Life Sciences (NARILIS), University of Namur, Namur, Belgium.
None:
Episodic hypoxaemia is associated with muscle dysfunction in respiratory insufficiencies, but its effects depend on the hypoxia/reoxygenation pattern. Sustained Intermittent Hypoxemia (SIH) characterizes a large subgroup of COPD patients, yet muscle adaptations to SIH remain poorly known. We used a mouse model of SIH (FiO₂: 10%, 8 h/day) and analysed myofibre structure, muscle mass regulators, and myogenic markers in fast and slow-twitch hindlimb muscles. SIH induced an increase in haematocrit. At 35 days, Soleus cross-sectional area increased predominantly in slow-twitch fibres, but not in the fast Tibialis Anterior (TA) muscle. HIF1 target gene expression was increased at early timepoints with muscle-type-specific differences. While myostatin plasma levels were decreased, myostatin receptor and atrogene expression differed between muscles at baseline and upon SIH. Myod1 and Myog expression decreased over time in the TA only. In conclusion, SIH induces muscle-type-specific adaptations, promoting hypertrophy in slow-twitch muscle while impairing myogenic regulation in fast-twitch muscle.
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