Growth sites are found at the ends of the longest bones and involve joints like the knee or elbow. Common growth site injuries include: runner's knee, jumper's knee, Achilles tendinitis, and shin splints. In rare cases, the growth plate will stop growing altogether. Young female runners are at risk for the female athlete triad. The female athlete triad includes eating disorders in the female runner. Running emphasizes a lifestyle that requires a specific diet to keep the runner healthy. Eating disorders are also likely to occur in young gymnasts going through puberty. During puberty, a young woman's center of gravity can change, making tricks that were previously easy seem almost impossible. In order to stay smaller, the gymnast will reduce his food consumption. Runners tend to want to stay slimmer and this pressure can cause them to restrict their diet. This decrease in nutrient intake will cause the second factor in the female athlete triad. Puberty is an important time for a girl's bone growth. By reducing the nutrients a girl receives, bones become brittle and can cause early osteoporosis. Osteoporosis is the weakening of bones and is normally thought of as 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 can break suddenly and stress fractures are much more common.