most crucial aspects of such testing because it serves as a way of communicating with participants, health and school officials, and parents about their risk of negative health outcomes based on test performances.
To illustrate the overall challenge of its task and create a model for physical fitness measures that are most clearly associated with health outcomes in youth, the committee developed a conceptual framework (Figure 3-1). This framework guided the committee’s analysis of research findings. Figure 3-1 depicts the potential relationships between physical fitness components—which can be measured by a variety of fitness test items represented by the smaller embedded boxes—and markers of health.
As illustrated in Figure 3-1, these relationships can be affected by both modifying factors and risk factors. As defined by the committee, modifying factors are those that can independently affect an individual’s level of fitness. They include both factors that are measurable in the field (e.g., gender, race, ethnicity, maturity) and those that are not (e.g., heredity, practice level, skill level). Likewise, health outcomes are modified by certain risk factors that characterize an individual (e.g., low HDL cholesterol is a risk factor for cardiovascular disease). In the case of youth, health outcomes (i.e., diseases or conditions) are defined in terms of health markers or risk factors since youth are unlikely to experience a disease or condition (e.g., heart disease) as a result of their fitness level. The potential health outcomes that result from a specified level of performance on a fitness test are depicted within five categories: four categories of (positive or negative) markers of health-related outcomes (i.e., cardiovascular/respiratory health, metabolic health and obesity, mental and cognitive health, and musculoskeletal health) and a category that includes adverse events. Note that in this report, the terms health marker and health risk factor are used in a broad sense and interchangeably to refer to indicators of health outcomes.
The committee included body composition as a component of fitness, even though perspectives on this categorization vary. Body composition is also considered a modifier of performance on fitness tests and a health marker. Thus, it appears in all three categories of variables in the framework—fitness components, modifying factors, and health markers—and is highlighted in a different color from that of the other fitness components because of this unique nature.
The next section describes the approach used by the committee to select the best youth fitness test items, considering (1) the strength of their association with health markers in youth, (2) their integrity (validity and reliability), and (3) the relative feasibility of their administration in the field.