Rocks in various structures are subjected to periodic mechanical stresses. These include, for example, crushed stone used in railroad tracks and in the asphalt concrete of highways, crushed pieces of rock during its processing, rock massif in the extraction of minerals during boring and tunnelling using blasting, a salt rock massif around underground hydrocarbon stores with seasonal fluid pressure changes, etc. The report discusses changes of the strength and acoustic quality factor of rocks of various types depending on the number of periodic cyclic mechanical effects on samples during compression, tension and bending with maximum and minimum loads of the same sign. Limestone, travertine, and gabbro show a strength decrease. Marble and rock salt show the possibility of both reducing and restoring strength. This can be taken into account in cases where it is necessary to either maintain or reduce the strength of the rocks.