Sport and its implications on the bone health of adolescent athletes

A strong emphasis has been placed on the effects of sports on bone mass and possibility of preventing future osteoporosis1, considering that strenuous physical exercise plays a crucial role in the bone mass gain process2. The load mechanisms from the exercises increase bone mineral density, regardless or gender and age of those who practice them3. Bone tissue dynamically responds to the imposed functional demand, causing changes in mass and strength. These changes are a result of gravity and the intense action of bone-related muscles4. The adaptative bone response will thus depend on the magnitude of the load and the frequency it is applied, as regular repetitions trigger osteogenic effects2,5. Bone mass accounts for about 80% variation in bone strength, but other factors such as bone geometry, the internal architecture, and mechanical properties also affect the strength of a given bone1. The continuous stress from physical exercise leads to morphological adjustments, such as increase of cortical thickness, and more bone content in the muscle-tendon insertion4. For other investigators, the mechanisms by which the skeleton responds to physical training are not yet fully understood1. Even though there are some controversies in the literature on the adaptation mechanisms of bone tissue exposed to external loads, the impact of strenuous physical exercise on bone mass is relevant during adolescence, when bone mass peak is yet to be reached1,6,7. The increase of bone mineral density over puberty is basically due to bone enlargement from the growth process, and further increase if cortical thickness1. Investigations have suggested that bone mass enlargement during growth process and immediately after it may represent an important strategy for osteoporosis prevention1,5. These authors report that a 3 to 5% increment of bone mineral density causes a 20 a 30% decrease in the risk of fractures. There are evidences that the peak growth period is the most effective time to potentialize bone mass gains, compared to the late adolescence period8. Sport and its implications on the bone health of adolescent athletes