FITNESSGRAM, a national youth fitness test battery, includes tests of four different parts of health-related physical fitness: body composition, cardiovascular fitness, muscle fitness, and flexibility. National guidelines recommend daily physical activity of 60 minutes or more to build all parts of fitness and to achieve other health benefits. Activities of all types from the Physical Activity Pyramid for Kids should be performed. Moderate activity (Step 1) contributes to general health benefits. Vigorous aerobic activity (Step 2) and vigorous sports and recreation (Step 3) build cardiovascular fitness. Muscle fitness exercises (Step 4) build muscle fitness, including strength and muscular endurance. Flexibility exercises (Step 5) build flexibility, including long muscles and good range of joint movement.
Body Composition refers to the makeup of body tissues, including muscle, bone, body fat, and other body tissues. For good health, a high amount of lean tissue (e.g., muscle, bone) and a relatively low amount of body fat is desired. However, a healthy amount of fat (essential fat) is necessary for normal body functioning.
FITNESSGRAM offers two methods of assessing body composition. The first, and most commonly used method, is the Body Mass Index (BMI). BMI is calculated using height and weight measurements. It is a good screening tool but may show some muscular youth to be "overweight" when they are high in muscle and other lean tissue. The second method is skinfold testing. Calipers are used to measure the thickness of fat under folds of skin on the back of the arm (triceps measure) and side of the calf (calf measure). The thicknesses of these skinfolds are used in a formula to predict percent body fat. This method is more intrusive but, because it measures fat, it is considered to be more meaningful measure (when done by a trained person) than BMI.
It is well known two to three times as many youth are overweight or obese than in the 1980s. The American Academy of Pediatrics recommends that all children be screened to prevent early excessive weight gain. After screening, steps can be recommended to help youth maintain a healthy body composition throughout life. Parents are wise to consider fitness test results, and results of assessments by physicians, and to discuss them with their physician.
Energy balance, a balance of energy (calories) expended and energy (calories) consumed, is necessary to maintain a healthy body composition. The 60 minutes of recommended daily activity (energy expended) for youth can come from any of steps of the Physical Activity Pyramid. Some of the activity should be vigorous in nature and some from muscle fitness exercises that have the special benefit of building muscle and bone. Of course, eating a healthy diet is crucial to energy balance and a focus on eating health foods and avoiding empty calories is essential. The vertical color bands on the right side of the pyramid are present to show the importance of healthy eating.
Unfortunately, studies show that often parents hold misconceptions related to body composition. For example, many consider their children to have a healthy body composition when they do not. But then many adults also consider themselves to have a healthy weight when they do not. Studies show that many Americans underestimate what they eat, and overestimate the amount the exercise that they do. Self-monitoring of eating and exercise habits can help build accurate perceptions, not only for youth but for adults as well. Parental support for school-based activity programs, and healthy lunches and snacks, can contribute significantly to fighting the childhood obesity epidemic.
Screening at school using body composition measures, such as those in FITNESSGRAM, or being assessed by a physician, can be a good first step. Screening should be followed with additional assessments and consultation. Body composition is important and not something to be ignored in youth. Depending on age group, 15 to 19 percent of youths are overweight or obese, but nearly two-thirds of adults are classified as such. Early detection can help your child or teen have a healthy body composition.
Ahwatukee Foothills resident Dr. Charles B. "Chuck" Corbin is professor emeritus at Arizona State University, author of more than 90 books on fitness and activity, and was the first chair of the President's Council on Physical Fitness, Sports, and Nutrition Science Board. For more information on the National Physical Activity Guidelines for Americans, go to www.health.gov/paguidelines.