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2008 Physical Activity Guidelines for Americans - Funding Opportunities & Research Resources for Researchers

The Federal Government has issued its first-ever Physical Activity Guidelines for Americans. They describe the types and amounts of physical activity that offer substantial health benefits to Americans. Accompanying the guidelines is an Advisory Committee Report that reviewed existing scientific literature to identify evidence to develop the physical activity recommendations. Although a substantial amount of research on physical activity and health has been published since 1995, major gaps still exist in our knowledge needed to establish cause and effect for various health outcomes and to better define dose response, especially at the low and high ends of the activity spectrum. These gaps are highlighted in Part H: Research Recommendations in the Advisory Committee Report.

The following presents the Research Recommendations from the report. For each topic area, we have highlighted relevant NCI and NIH funding opportunities for researchers who wish to explore these remaining gaps in the scientific evidence. Also listed are links to information about surveys, databases, and other NCI and NIH research resources that could help answer specific research questions under several of the topic areas.

Dose Response

  • Some recently published data indicate that physical activity of a lower intensity and/or smaller amount than is currently recommended may provide significant health benefits for chronically inactive or unfit adults (who comprise a large proportion of the American population aged 18 years and over) and older adults. Both experimental and observational studies are needed to answer a variety of questions about the nature of benefits provided and characteristics of dose required at the low end. The range of physical activity used in the intervention should include a dose below that currently identified in physical activity recommendations to evaluate its impact and the stability of this level of physical activity behavior over time.
  • There remains a lack of data defining both the shape of the dose-response curve at the higher amounts and intensities of activity for most health outcomes and whether an upper limit of benefit exists. Most current recommendations focus on a minimal or target amount/intensity of activity that is consistent with much of the population receiving some benefit, but don't address questions of "optimal" or "maximal" benefit. Studies are need to clarify the amount of physical activity, defined by metabolic equivalent (MET)-minutes per week or some other measure, at which additional improvements in various health outcomes no longer occur or at which increases are negated by increased adverse medical events.
  • To fill the gap in our knowledge about dose response, investigators should design and conduct studies that evaluate effects of the following variables at fixed volumes of physical activity: intensity, frequency, duration, and multiple bouts. Details related to these variables would allow more precise physical activity guidelines to be developed across the breadth of activity-related health outcomes.
  • Reasonable evidence exists that activity accumulated in short bouts throughout the day can favorably alter selected biomarkers for cardiovascular and metabolic diseases and improve cardiorespiratory fitness. However, no evidence is available that such patterns of activity may be beneficial for musculoskeletal health. Experimental studies are needed to extend this research involving activity bouts of different durations, especially multiple bouts shorter than 10 minutes and a few long bouts per week (e.g., 2 x 75 minutes) on various health outcomes. Observational studies are needed using assessment methodologies that will allow accurate quantification of a range of types of activity in different population groups (e.g., abdominally obese, frail elderly) and an evaluation of the effect of accumulation of short bouts on clinical outcomes independent of activity intensity and amount.

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Energy Balance

  • Additional large scale, multi-site RCTs are needed to more thoroughly characterize the dose response of physical activity on weight stability, weight loss, and body composition across a variety of population groups, especially for those in the normal body mass index range. Only a limited number of RCTs have addressed these outcomes. Large-scale multi-site RCTs would allow investigators to more effectively address issues related to susceptibility to weight gain or resistance to weight or fat loss that may vary by sex, race/ethnicity, and age. As mentioned in the overarching recommendations, various volumes should be evaluated within the same study design.
  • Determine the most effective strategies for promoting and maintaining sufficient doses of physical activity to facilitate weight loss and/or weight stability. It is important to develop effective intervention strategies to promote and maintain the desired level of physical activity for weight loss and/or weight stability because adherence to this level of physical activity is currently less than optimal. Although some strategies have been shown to be effective for improving adherence to this level of physical activity, the success of these strategies has been demonstrated in limited samples and populations. Therefore, additional research in this area is needed.
  • Determine how much physical activity is needed to prevent weight regain following weight loss. Most of the available literature related to this question is observational or has relied on retrospective analysis of self-selected and self-reported levels of physical activity. Use of state-of-the art technology and complete energy balance designs are absent from the literature. Specifically, it appears that no adequately powered studies of sufficient duration with randomization have been conducted to examine different levels of physical activity following weight loss.
  • Determine the physical activity effects on total and regional fat loss from those of weight loss, per se, especially in those people very susceptible to weight gain in the current social environment and who thus may be most resistant to weight or fat loss with exercise. Additional RCTs are needed to distinguish physical activity effects from weight loss effect. In addition, the large-scale use of imaging techniques is necessary to distinguish between subcutaneous and visceral fat depots in their responsiveness to endurance and/or resistance training. The ability of studies to translate imaging findings into simple anthropometric measures such as the waist or the abdominal circumference would increase the clinical and personal utility of the research.
  • More research is needed to establish the risks and benefits of various regimens of physical activity in men and women with a body mass index of 35 or greater.

Research Resources

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Cancer

  • Knowledge about the role of physical activity in reducing the risk of common cancers would benefit from additional evidence gathered from clinical trials. In the survivorship setting, clinical trials showing a benefit of physical activity interventions on reducing deaths, recurrences, and reducing the impact of late or long-term treatment effects also would make a valuable contribution to our understanding of the needs of this growing population.
  • Studies are needed to clarify biological mechanisms linking physical activity to specific cancers in order to identify associations with less commonly studied cancers.
  • Studies are needed to define the shape of the dose-response curve of the physical activity-cancer relation in order to determine the effect of low-intensity activities and accumulated bouts.
  • Observational epidemiologic research is needed to identify the dose, type, and frequency of physical activity on risk of various cancer sites and subtypes, in addition to identifying the effect of physical activity on risk of specific cancers within particular population subgroups, including various races and ethnicities, ages, sexes, and groups at elevated risk of cancer.

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Youth

  • Determine whether physical activity affects classroom behavior and academic achievement in children and adolescents.
  • Determine whether physical activity affects depression, anxiety, and cognitive function in children and adolescents.
  • Determine the types and amounts of physical activity that are needed to prevent the development of excessive adiposity during childhood and adolescence.
  • Identify the optimal types and amounts of physical activity needed to maintain cardiorespiratory and metabolic health during childhood and adolescence.
  • Establish the dose-response pattern for the relation between physical activity and bone health in children and adolescents.

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Participant Diversity & Racial/Ethnic Diversity

  • An increased number of Federally-funded studies should be powered to include sufficient representation of at least one ethnic/minority or lower SES population, with sufficient sample size to permit subgroup analyses by race/ethnicity or SES. Strict exemption criteria should be rigorously applied.
  • Cultural proficiency of recruitment and retention approaches and adequacy of resources directed toward recruitment and retention should be scrutinized by grant review committee members with special expertise in this area, similar to the separate assessments of adequacy of study methods and analytical approaches by review committee statisticians.
  • Federal program officers should manage and balance their portfolios to ensure that racial/ethnic differences in physical activity-related exposures and outcomes are under active investigation, and should use requests for applications (RFAs) and other mechanisms to direct funding toward disparities examination and elimination.
  • Journals should require reporting of race/ethnicity, sex, and SES of samples in the abstract as well as the body of the text.
  • Subgroup analyses should be requested when sample size is sufficient, and further data desegregation should be encouraged to examine interactions between sociodemographic characteristics, e.g., sex-ethnicity, SES-ethnicity.
  • Abstraction databases should include search criteria that permit ascertainment of inclusiveness (i.e., subgroup analyses by race/ethnicity or SES).
  • Specific research questions deserve particular emphasis, such as the precise role in weight maintenance of racial anthropomorphic variations in resting or activity-related energy metabolism (as opposed to or in concert with age- or sex-related differences) in body composition.
  • Journal standards for peer-reviewed articles should require a reporting of the race/ethnicity (in addition to sex and age) of the sample and presentation of subgroup analyses by race/ethnicity and/or SES if sample sizes are sufficient, rather than simply treating these as co-variates and adjusting for them.

Funding Opportunities

  • Health Promotion Among Racial and Ethnic Minority Males

Research Resources

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Measurement Methodology

  • Uniform data collection is needed with respect to the type of physical activity (e.g., leisure-time, occupational) and physical activity characteristics (e.g., intensity, duration, amount).
  • The Compendium of Physical Activity has been very useful in assigning standardized values of absolute intensity to a wide range of activities, but it should be updated and expanded to children and youth.
  • During the past decade, technology that provides for the objective assessment of physical activity in relatively large groups of subjects has increased rapidly, especially through the use of motion sensors and physiological monitoring. These technologies have the potential to greatly improve the accuracy and reliability of physical activity assessment in free-living populations leading to a better understanding of health benefits and dose response. Development and evaluation of these technologies are needed for assessing populations with different activity profiles and sociodemographic characteristics.
  • A much better understanding is needed on how the results of physical activity assessed by new objective measurement methods can be compared to data collected by commonly used questionnaires.
  • Because of the scientific and logistical challenges of including adequate-sized samples of multiple groups in a study conducted at one institution, well-designed and executed multi-center studies are needed in which each research site can have access to subjects who represent various specific understudied populations. This is critically important in providing investigators with opportunities to examine interactions between sociodemographic factors, particularly sex and race/ethnicity or SES, and physical activity in relation to health and to make inter-group comparisons.
  • Funding agencies should support well-designed studies of individual understudied populations, especially race/ethnic minorities, persons of low SES, and individuals with physical and cognitive disabilities, so that major questions regarding the effects of exercise and effectiveness of physical activity interventions in each of these populations can be answered. If an organization funded a number of such studies with at least a core of shared measures, they would have a well-diversified research portfolio on understudied populations. Such an approach would more likely answer key questions than would an approach that requires each investigator to include relatively small numbers of understudied populations in their studies.

Funding Opportunities

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Physical Activity and Physical Fitness Surveillance

  • Surveillance of the total activity energy expenditure of representative samples of the US population needs to be implemented once appropriate assessment tools have been developed and validated. Such tools could include either questionnaires or new objective measurement technology, or a combination of the two.
  • Special attention needs to be given to the surveillance of both the physical activity and physical fitness of the US population at both ends of the age spectrum -- toddlers/children and the oldest adults. These groups constitute a substantial portion of the US population and receive unique benefits from being physically active, but no national surveillance system for physical activity or physical fitness data exist for them.

Research Resources

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Systematic Reviews and Meta-Analyses

  • Experts investigating specific health outcomes from physical activity should assess the nature and volume of recent publications and determine whether quantitative reviews of the data would contribute to existing knowledge, help formulate guidelines and policy statements, and help set research priorities.

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Last Modified: 11 Apr 2014