ACSM'S Health & Fitness Journal:
DEPARTMENTS: Fitness Focus
Thompson, Dixie L. Ph.D., FACSM
Dixie L. Thompson, Ph.D., FACSM, is the director of the Center for Physical Activity and Health and professor and department head for the Department of Kinesiology, Recreation, and Sport Studies at the University of Tennessee, Knoxville.
There are numerous physiological and psychological benefits to being physically active. However, not everyone who exercises is healthy. In fact, finding a way to balance the demands of athletic competition against maintaining good health sometimes becomes a challenge for athletes. The female athlete triad is a condition that can occur in female athletes who do not consume adequate calories to maintain good health. This low-energy availability contributes to various health problems, including loss of bone mineral density and irregular menstrual cycles.
To maintain good health, a person needs to eat enough calories to fuel exercise and also support the body's normal functions, such as thermoregulation, reproduction, and cellular maintenance. Low-energy availability occurs when an individual does not consume enough calories to support these functions. When the female athlete triad initially was defined, eating disorders were identified as a root cause. Scientists and physicians now recognize that low-energy availability can occur with or without clinical eating disorders (e.g., anorexia nervosa, bulimia).
The mismatch between energy needs and energy intake occurs when athletes increase exercise and/or reduce energy intake without consideration for the importance of energy balance. Dieting for weight loss is a common beginning point for athletes with the female athlete triad. Low-energy availability particularly is prevalent in sports where a lean body physique is required or perceived to be important. In cases where eating disorders exist, it is important to obtain professional support for overcoming these potentially life-threatening conditions.
MENSTRUAL CYCLE DYSFUNCTION
When energy availability is low, the body shifts calories to immediately life-sustaining activities. When energy availability is low for a period, irregular menses can result. Normal menses, eumenorrhea, can be maintained even in heavily training athletes. However, a number of studies have reported that athletes, including distance runners, dancers, and gymnasts, are much more likely to have irregular menstrual cycles compared with nonathletes. Amenorrhea is a term used to describe a lack of menses of more than 3 months, whereas oligomenorrhea is irregular menses with cycles longer than 35 days. Female hormones associated with menstrual cycles are important for the body's normal functioning, including sustaining strong bones.
LOSS OF BONE MINERAL DENSITY
Bones continually are being remodeled. In other words, old bone is being replaced with new bone. In growing children, more bone is made than is broken down. During much of adult life, bone breakdown equals bone building. After approximately age 50 years, more bone is lost than is made, thus, bone becomes weaker. Bone mineral density is the common clinical measure of bone strength. Healthy athletes typically have stronger bones (higher bone mineral density) than nonathletes. However, athletes with the female athlete triad have low bone mineral density. Loss of bone mineral density occurs because more bone is broken down because of hormonal imbalances, and less bone is made because of poor nutrition. The result is bones that are much more susceptible to stress fractures and other types of breaks.
It is important for coaches, parents, friends, and sports medicine professionals to be aware of the female athlete triad. Athletes who are struggling with eating disorders and/or other problems associated with the triad need assistance to overcome these health challenges. More information on the female athlete triad can be found in ACSM's Position Stand on this topic. Visit www.acsm.org to find this and other important health information from ACSM.
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