148 Anatomy & Physiology Essentials Copyright Goodheart-Willcox Co., Inc. or menses—and osteoporosis. Because the triad can cause negative health consequences ranging from irreversible bone loss to death, friends, parents, coaches, and physicians need to be alert to the signs of this condition. Female athletes participating in endurance or appearance-related sports are most likely to be affected by the female athlete triad. Disordered eating can take the form of anorexia nervosa or bulimia nervosa. Symptoms of anorexia nervosa in girls and women include a body weight that is 15% or more below the minimal normal weight range, extreme fear of gaining weight, an unrealistic body image, and amenorrhea. Bulimia nervosa involves a minimum of two eating binges per week for at least three months an associated feeling of lack of control use of self-induced vomiting, laxatives, diuretics, strict dieting, or exercise to prevent weight gain and an obsession with body image. are osteoporosis-related. In the elderly population fractures of the femoral neck, in particular, often trigger a downward health spiral that leads to death. The most common symptom of osteoporosis, how- ever, is back pain derived from crush-type fractures of the weakened trabecular bone of the vertebrae. These fractures can be caused by activities as simple as picking up a bag of groceries or a bag of trash. Vertebral crush fractures frequently cause reduction of body height and tend to accentuate the kyphotic curve in the thoracic region of the spine. The Female Athlete Triad Unfortunately, osteoporosis is not confined to the elderly population. It can also occur in female athletes at the high school and collegiate levels who strive to maintain an excessively low body weight. Striving for an extremely low weight can cause a dangerous condition known as the female athlete triad. This condition involves a combination of disordered eating, amenorrhea—having no period Preventing Osteoporosis Osteoporosis is not inevitable with advancing age. It is typically the result of a lifetime of habits that are erosive to the skeletal system. Simply stated, it is easier to prevent osteoporosis than to treat it. The single most important strategy for preventing or delaying the onset of osteoporosis is maximizing bone mass during childhood and adolescence. Weight-bearing exercise such as running, jumping, and even walking is particularly important prior to puberty because of the high level of growth hormone present during this period. Growth hormone makes exercise particularly effective in increasing bone density. Diet also plays an important role in bone health. Physicians now recognize that a predisposition for osteoporosis can begin in childhood and adolescence when a poor diet interferes with bone mass development. Adequate dietary calcium is particularly important during the teenage years, but unfortunately the typical American girl falls below the recommended daily intake of 1,200 mg per day by 11 years of age. A modifi ed diet or calcium supplement can be critical for the development of peak bone mass among adolescent females who have this dietary defi ciency. The role of vitamin D is also important, because vitamin D enables bone to absorb calcium. In North America, more than 50% of women being treated for low bone density also have a vitamin D defi ciency. Other lifestyle factors also affect bone mineralization. Risk factors for developing osteoporosis include a sedentary lifestyle, weight loss or excessive thinness, and smoking tobacco. To help prevent later development of osteoporosis, young women are encouraged to engage in regular physical activity and to avoid the lifestyle factors that negatively affect bone health. Research Notes Ekaterina Markelova/Shutt erstock.com Common sources of calcium and vitamin D. Eating a balanced diet that includes a variety of foods like these helps young people achieve normal, healthy bone mass.