The growth sites are located at the ends of the longest bones and involve joints such as the knee or elbow. Common injuries at the growth site include: runner's knee, jumper's knee, Achilles tendonitis, and shin splints. In some rare cases the growth plate will stop growing completely. Young runners are at risk for the triad of female athletes. The female athlete triad includes disordered eating in the runner. Running emphasizes a lifestyle that requires a specific diet to keep the runner in good health. Disordered eating is also likely to occur in young gymnasts going through puberty. During puberty, a young woman's center of gravity can change, making stunts that were previously easy seem nearly impossible. To stay smaller, the gymnast will reduce food intake. Runners tend to want to stay leaner, and this pressure can cause them to limit their nutrition. This reduced nutrient intake will cause the second factor of the female athlete triad. Puberty is an important time for a girl's bone growth. By decreasing the nutrients a girl receives, bones become brittle and can cause early osteoporosis. Osteoporosis is the weakening of bones and is normally considered a condition that only affects older women, but some extreme runners have been known to suffer from osteoporosis in their twenties. Runner's bones are so fragile that they may break suddenly, and stress fractures are much more