Our work was aimed to study glycogen-like granules in muscular fibres mitochondria under action of different factors (maximum physical load, hypokinesia and saturation of the organism with carbohydrates). Swelled mitochondria with glycogen-like granules were shown in muscular fibres in physical load. Similar mitochondria but without granules were observed in hypokinesia. In saturation with carbohydrates granule-containing mitochondria were not rarely encountered, so as myelin figures instead of mitochondria with plenty of glycogen-like granules seen in the centre. Glycogen-like granules appearance in mitochondria is likely to be an original adaptation, aimed to maintain energy production on a certain level.