De Palma et al. published a research paper in which they describe the effect of chronic hypoxia on rat skeletal muscle metabolism by means of a comparative proteomic analysis (J. Proteome Res. 2007, 6(5), 1974-1984). For this, relatively young animals were used. In our communication, we note that, based on other literature, it is likely that the adaptive response of skeletal muscle to hypoxia attenuates with age. Keywords: skeletal muscles * hypoxia * muscle fiber types * energy metabolism * hypoxia inducible factor 1alpha (HIF1alpha).