Even with this resource, however, it can be challenging for users to choose the most appropriate measures for their work. To address this need, NCCOR began the Measures Registry User Guide project in 2015. Organized by the same four domains as the Measures Registry, the User Guides are designed to provide an overview of measurement, describe general principles of measurement selection, present case studies that walk users through the process of using the Measures Registry to select appropriate measures, and direct researchers and practitioners to additional resources and sources of useful information (Figure 1). The User Guides will help move the field forward by fostering more consistent use of measures, which will allow for standardization, meta-analyses, and synthesis.

Overview of the Individual Physical Activity Measures Guide

This Guide focuses on enhancing use of measures and tools in the Individual Physical Activity category. Accurate estimates of physical activity are essential for advancing research on the health benefits of physical activity; for understanding patterns and correlates that influence physical activity behavior; and for evaluating interventions designed to promote physical activity, improve health, or reduce obesity. Indicators of physical fitness (including body fatness) have generally shown stronger links with health indicators than with physical activity. However, this is due in part to the less precise methods available to assess physical activity. Physical activity directly improves fitness (and body composition) and consensus suggests that it improves health independently of both fitness and fatness. These findings clearly justify the emphasis on physical activity for advancing public health research focused on obesity and health.

Considerable attention has been given to improving physical activity assessment methods but progress has been hampered by limitations in the way that physical activity measures are used, scored, and interpreted. Many options are available for assessing physical activity, so it is important to appreciate and consider the relative advantages and disadvantages of the various measurement approaches. Decisions typically depend on the type of study or project being conducted as well as on the degree of precision needed for the assessment. However, consideration must also be given to the inherent challenges in collecting, processing, scoring, and interpreting physical activity data. Specific expertise may be needed to appropriately process and interpret data (particularly when using electronic monitoring devices). The various decisions and challenges involved can make it extremely difficult for researchers and practitioners to select, find, and use physical activity assessments effectively. Obtaining accurate assessments of physical activity is challenging in all populations but the issues are even further complicated when studying youth due to a variety of age and maturation effects.

A primary goal of the NCCOR Measures Registry is to move the field toward a more consistent use of common physical activity measures and research methods so that science (and practice) in childhood obesity prevention can progress in a systematic way. Consistent with this goal, the present Guide is designed to help users of the Measures Registry make informed decisions when selecting and using measurement tools to assess physical activity behaviors in youth. It is not intended to provide a comprehensive review of specific instruments, strategies, or assessment frameworks, as many excellent reviews have already been published.^1-4 Instead, it fills a different niche by emphasizing the measurement issues that should be considered when selecting and using physical activity measures in research and other evaluation contexts.

In its report Bridging the Evidence Gap in Obesity Prevention, the National Academy of Medicine (formerly known as the Institute of Medicine) established a decision-making framework called L.E.A.D. (Locate Evidence, Evaluate it, Assemble it, and Inform Decisions) to guide the progression of research on obesity prevention.⁵ This framework has proved to be a useful strategy for any type of decision-making process. It was used to guide a prominent public health workshop on physical activity measures⁶ and the concepts are also implicit in the vision and structure of the NCCOR Measures Registry. In this case, the NCCOR Measures Registry provides a definitive source to “locate evidence” while this Guide provides frameworks to evaluate options and to inform decisions about the best ways to assess physical activity.

Organization of this User Guide

The sections in this Guide build sequentially but can be reviewed independently depending on the needs or interests of the reader. Background information on measurement and evaluation principles is provided in the early sections along with coverage of physical activity terminology and calculations, as these provide the foundation for the Guide. Readers who have experience with physical activity assessment might consider jumping right to the set of Case Studies in Section 7 that summarize the factors that are most relevant for different types of research applications. Readers interested in deeper coverage on some topics can consult Section 8, Section 9, and Section 10, which provide supplemental information, although these sections only hint at the additional complexities and new methods being explored to further enhance methods.

Section 2. Behavioral Epidemiology Framework

provides a framework to understand the unique needs of different types of studies and an introduction to the various categories of physical activity assessment options. It is important to understand these distinctions because appropriate decisions depend on the nature of the study goals, the target population, the relative need for precision, and the role that the physical activity measure plays in the analyses.

Section 3. Key Concepts for Understanding Individual Physical Activity

describes the complexities of quantifying physical activity and the inherent challenges involved in assessing a multi-dimensional and dynamic behavior rather than a more stable construct or trait. Assessments are challenging in all population segments but they are further compounded in research with children due to children’s more sporadic activity behaviors, varying cognitive abilities, and different physiological responses as well as the inherent variability in growth and maturation.

Section 4. Measurement, Evaluation, and Statistics

provides an overview of measurement issues and key terminology, with a particular focus on the distinction between reliability and validity because these terms are reported for most of the tools in the Measures Registry. It is important to note that inclusion of a measure in the Measures Registry does not imply that a measure is recommended or that it has good psychometric properties. It is up to the researcher to evaluate the measurement properties for each tool and to determine the best measure for a specific application.

Section 5. Overview of Individual Physical Activity Assessment Tools

provides details about the strengths and limitations of different measurement tools by building on the psychometric properties and considerations outlined in Section 4. Methods are divided into criterion measures, monitor-based measures, and report-based measures and their relative utility is explained using a conceptual “feasibility/validity” continuum.

Section 6. Selecting Measures

compiles content from a number of sections and introduces a basic decision-making framework to facilitate the selection of appropriate assessment methods from the Measures Registry. Details of the typical measurement considerations involved in different types of research are summarized using the categories outlined in the behavioral epidemiology framework from Section 2.

Section 7. Case Studies

provides case studies to facilitate the application of the information in this Guide. Examples of different types of research are provided for the five distinct types of research described in Section 6. Different populations and outcomes are included in the scenarios to illustrate how the Measures Registry can be used to find details about specific tools.

Section 8. Supplemental Considerations for Monitor-based Methods

includes supplemental content that relates to continued advances in physical activity assessment research. Specific content is provided on new monitoring technologies and approaches with ecological momentary assessment, consumer-based monitors, and smartphone applications because these are dynamic growth areas in physical activity research.

Section 9. Supplemental Considerations for Evaluating Sedentary Behavior

includes supplemental material and content relevant to the evaluation of sedentary behavior. Many of the principles described in the Guide are relevant to the study of sedentary behavior, but this behavior also has unique considerations that must be taken into account.

Section 10. Supplemental Considerations for Scaling and Scoring METs in Youth

includes reference material and supplemental material for additional review. Specific consideration is given to implications for collecting and interpreting physical activity data on youth obtained from activity monitors and self-report instruments as they are the most commonly used tools. Readers are encouraged to review the references for additional information about some of the topics to obtain additional insights.

Section 11. Conclusion

References