: Osteoporosis is one of the most important problems associated with aging. Genetic and environmental agents affect the process of reducing bone mineral density (BMD). As environmental agents, mechanical load (something which exerts an opposing force on the system; hence system needs more power to perform that work) is the important factor, which affects BMD. Studies show that a variety of exercise programs, depending on the amount of mechanical load they apply to the bone, activate the signaling pathways involved in the process of osteoblast activation and reduce osteoclast activity. The effect of physical activity (PA) on BMD is a function of the intensity, duration, and type of program used. Although the existing literature shows that regular PA increases BMD and subsequently develops its strength, there are conflicting results regarding the effectiveness of exercise programs that confirm the need for further study in this area.