Fitness Measures and Health Outcomes in Youth
Physical fitness is a key tenet of health. It affects our ability to function and be physically active and, at poor levels, is associated with such health outcomes as diabetes and cardiovascular disease.
Physical fitness testing in American youth was established on a large scale in the 1950s. In the intervening decades, the underlying philosophies that have guided development of fitness testing protocols and specific test items used in test batteries have evolved considerably. An early focus on performancerelated fitness, measured by test items that relied heavily on power and speed, gradually gave way to an emphasis on health-related fitness, composed of components that were linked to health outcomes. Health-related fitness typically has been defined as including body composition, cardiorespiratory endurance, musculoskeletal fitness, and flexibility. Although extensive evidence links performance on specific measures of fitness to health outcomes in adults, such evidence in children and adolescents is less abundant and debate continues about the best fitness measures for youth. Using appropriately selected measures to collect fitness data in youth will advance our understanding of how fitness among youth translates into better health.
At the request of the Robert Wood Johnson Foundation, the Institute of Medicine (IOM) appointed a study committee to assess the relationship between youth fitness test items and health outcomes, recommend the best fitness test items, provide guidance for interpreting fitness scores, and provide an agenda for needed research. The IOM committee presents its findings and recommendations in Fitness Measures and Health Outcomes in Youth. For the purposes of this report, “youth” is defined as children aged 5-18.
Indicators for National Surveys
As one of its primary objectives, the IOM committee was asked to identify physical fitness test items for youth that are valid, reliable, and related to health outcomes, and that would be suitable to include in national surveys to assess healthrelated fitness in youth. The committee used a systematic review conducted by the Centers for Disease Control and Prevention as its primary evidence base. The committee examined studies measuring body composition, cardiorespiratory endurance, musculoskeletal fitness, and flexibility and found varying degrees of evidence. It found that a substantial body of evidence supports specific test items that are related to health for body composition and cardiorespiratory endurance. While adequate evidence supports the relationship between musculoskeletal fitness and health, there is less evidence linking specific musculoskeletal test items to health. The evidence linking flexibility and health in youth is the least convincing. Thus, the committee recommends that national surveys of health-related fitness in youth include selected measures of body composition, cardiorespiratory endurance, and musculoskeletal fitness.
The committee also recommends that developers of fitness test batteries use age- and genderspecific cut-points to identify individuals at risk of poor fitness-related health outcomes. A cut-point is a performance score above or below which a health risk may exist. Ideally, a cut-point is a standard value that is related to health. Often, interim values need to be used until the necessary data are available to establish health-related cut-points. The committee provides guidance for developing cut-points when all the necessary data exist, but also for developing interim cut-points when data are limited.