Physical activity is one of the factors affecting bone formation and remodeling. The most important stimuli taking place in bone structure occurs when a mechanical load, inherent to physical activity, is heavier and has a different distribution than usual. The intensity of the load is more important than the duration. The type of physical activity with the greatest osteogenic potential seems to be activity that includes non-stereotyped jumps in different directions. Low impact physical activity, which involves little mechanic stress, seems not to benefit bone mass. Therefore, sports that include vertical impact activities in which body weight must be borne are more beneficial for bone mass than those in which there is no impact, such as swimming. These benefits are specific to the area most heavily involved in the activity, given that the response of bone structure to mechanical load tends to be local rather than general.