Physical Activity Guidelines Advisory Committee Report
Part B. Introduction
Setting the Stage for Physical Activity
Guidelines for Americans
The Department of Health and Human Services (HHS) is entrusted with a
leadership position in the nation's government to promote, create, and maintain
a healthy America, and the President's HealthierUS Initiative establishes a
federal framework for wellness-related activities and programs. In May 2006,
Secretary Michael O. Leavitt announced prevention as one of his top ten
priority areas. The overarching agenda of the prevention priority is organized
around the four major principles of the HealthierUS initiative:
- Eat a nutritious diet
- Be physically active
- Get your medical screenings
- Make healthy choices
On October 27, 2006, Secretary Leavitt announced plans for the
development of federal Physical Activity Guidelines for Americans to be
issued in 2008 (http://www.hhs.gov/news/press/2006pres/20061026.html).
HHS is taking the opportunity to develop the first Physical Activity Guidelines
for the nation to serve as the benchmark and single, authoritative voice for
providing science-based guidance on physical activity for health promotion.
These new, comprehensive guidelines will help promote a culture of wellness in
the United States by providing essential and practical information to Americans
on physical activity and related health benefits.
To help establish the scientific rationale for physical activity
guidelines, HHS sponsored a workshop (October 23 – 24, 2006), organized by
the Institute of Medicine, in which a panel of 30 scientists and practitioners
reviewed the evidence relating habitual physical activity to various health
outcomes, with special emphasis on the prevention of major chronic diseases (http://www.nap.edu/catalog.php?record_id=11819 ). This overview of existing evidence indicated that frequent
participation in physical activity was strongly linked to better health status
throughout the life span. Given the high prevalence of sedentary behavior among
Americans and the current epidemic of obesity and related diseases, the panel
also concluded that federal physical activity guidelines were warranted.
The Physical Activity Guidelines Advisory
Committee
Following the announcement by the Secretary, nominations for potential
members of a Physical Activity Guidelines Advisory Committee (PAGAC) were
sought through a Federal Register Notice published in January 2007
http://edocket.access.gpo.gov/2007/E7-842.htm
[PDF - 52 kb]. Prospective members of the Committee were expected to have
knowledge of current scientific research in human physical activity and be
respected and published experts in their fields; be familiar with the purpose,
communication, and application of federal guidelines; and have demonstrated
interest in the public's health and well-being through their research and
educational endeavors. Expertise was sought in specialty areas related to
physical activity, including health promotion and chronic disease prevention;
bone, joint, and muscle health and performance; obesity and weight management;
musculoskeletal injury and other adverse events; and applications to specific
populations such as children, youth, and women during pregnancy and the
postpartum period, older adults, persons with disabilities, and diverse races
and ethnicities.
To the extent practicable, selection of committee members represented
geographic distribution and took into account the needs of the diverse groups
served by HHS. Appointments were made without discrimination on the basis of
age; race and ethnicity; sex; sexual orientation; disability; or cultural,
religious, or socioeconomic status. In February 2007, Secretary Leavitt
appointed 13 members to the PAGAC, including a chair and vice chair. The
Committee served without pay and worked under the regulations of the Federal
Advisory Committee Act.
Charge to the Committee
Secretary Leavitt's charge to the Committee was to "review existing
scientific literature to identify where there is sufficient evidence to develop
a comprehensive set of specific physical activity recommendations. The
Committee is to prepare a report to the Secretary that documents scientific
background and rationale for the 2008 edition of the Physical Activity
Guidelines for Americans. The report will also identify areas where further
scientific research is needed. The intent is to have physical activity
recommendations for all Americans that will be tailored as necessary for
specific subgroups of the population" http://edocket.access.gpo.gov/2007/E7-842.htm
[PDF - 52 kb].
Committee Meetings
The committee held three 2-day meetings in Washington, DC, that were
open to the public and announced in the Federal Register. The meetings
took place on June 26 – 27, 2007; December 6 – 7, 2007; and February
28 – 29, 2008. Meeting summaries are available at
http://www.health.gov/paguidelines.
Oral comments from the public were presented at the second and third
public meetings, and written comments were accepted throughout the tenure of
the PAGAC. Written comments were shared with the Committee before the second
and third meetings and as Committee members were drafting their final report.
These comments are available for examination at the Office of Disease
Prevention and Health Promotion, 1101 Wootton Parkway, Suite LL-100, Rockville,
MD 20852.
Committee Organization and Work Process
Soon after the PAGAC was convened, members decided that the work of
reviewing the science would be best achieved by establishing subcommittees,
each of which would review and interpret the literature for specific health
outcomes and summarize their findings as a chapter in the report. The
subcommittees, composed of Committee members and consultants, communicated by
electronic mail and conference calls and held face-to-face meetings before the
public Committee meetings. Each subcommittee was responsible for presenting to
the full Committee the basis for its conclusions, responding to questions, and
making changes if indicated. The conclusions in this report represent the
consensus of the entire PAGAC.
Initially, the PAGAC formed 9 subcommittees, focused on the 9 health
outcomes identified by the CDC (see below): all-cause mortality,
cardiorespiratory health, metabolic health, energy balance, musculoskeletal
health, functional health, cancer, mental health, and adverse events. At their
first public meeting, members added two other subcommittees: youth and
understudied populations (i.e., populations not covered in other chapters
— persons with disabilities, women during pregnancy and the postpartum
period, and races and ethnicities other than non-Hispanic white).
Each Committee member volunteered to chair one subcommittee and be a
member of one or more other subcommittees. To assist in the review process,
subcommittee chairs were authorized to select consultants who had scientific
expertise in a specific area of the subcommittee's charge (consultants are
listed at the beginning of the report).
A Systematic Review of the Evidence on
Physical Activity and Health
Immediately after Secretary Leavitt announced plans for the development
of federal physical activity guidelines, staff of the Division of Nutrition,
Physical Activity, and Obesity (DNPAO) at the Centers for Disease Control and
Prevention's (CDC's) National Center for Chronic Disease Prevention and Health
Promotion were assigned to develop a process to support the systematic review
of the scientific literature relating physical activity to health. The staff
developed a conceptual framework for the literature search and a process to
systematically abstract published articles and make these abstracts readily
accessible to PAGAC members and consultants. The details of this search
strategy and process are provided in Part
F: Scientific Literature Search Methodology. The product
resulting from this search and abstracting process is the Physical Activity
Guidelines for Americans Scientific Database. CDC staff initially decided
to abstract relevant articles published between January 1, 1995 and December
30, 2006. In June 2007, the PAGAC and CDC agreed to expand the abstracting
process to include articles published between January 1 and August 10,
2007.
The Committee's Review of the Scientific
Literature
PAGAC members were instructed on and encouraged to use the Physical
Activity Guidelines for Americans Scientific Database to identify articles
that would be included in each subcommittee's systematic review of the
literature. Also, as each subcommittee developed a plan to review and interpret
the scientific data, it made arrangements with the CDC staff and PAGAC
leadership for additional abstracting of articles that were central to their
review. Because of limited time and resources available, additional abstracting
was prioritized based on the importance and relevance of the outcome being
addressed. Because not all the relevant literature could be abstracted by the
CDC, subcommittees also were encouraged to consider using recent meta-analyses
or systematic reviews for various biomarkers or risk factors that appear to be
in the causal pathway between activity and a specific clinical outcome (e.g.,
hypertension or atherogenic lipoproteins for coronary heart disease).
Subcommittees were instructed to carefully document in their chapters the
literature search and review methods they used.
Following their literature review, each subcommittee drafted a chapter
that summarized and synthesized the results of the review. These chapters were
subsequently reviewed by at least 3 PAGAC members who were not members of the
drafting subcommittee as well as selected consultants. All PAGAC members were
encouraged to review all chapters.
Summarizing and Integrating the
Science
In addition to summarizing the evidence relating physical activity to
individual health outcomes, one of the PAGAC's major goals was to integrate the
scientific information on the relation of physical activity and health and to
summarize it in a manner that could be used effectively by HHS personnel to
develop the Physical Activity Guidelines and related statements.
For the final PAGAC meeting, each subcommittee chair was requested to
prepare a brief summary of key findings from their chapter for discussion by
PAGAC. Each subcommittee's summary report included information on the type and
magnitude of evidence, the strength of the evidence, characteristics of the
physical activity most likely to produce the outcome, any evidence of a
dose-response association, and any evidence that being sedentary puts a person
at increased risk. Selected PAGAC members then were asked to integrate the main
conclusions from these subcommittee reports under the headings of youth,
adults, older adults, understudied populations, and adverse events. These
summary conclusions were presented and discussed at the PAGAC meeting on
February 29, 2008. The resulting summary of evidence and consensus statements
about the relation of physical activity to health are provided in
Part E: Integration and Summary of the
Science.
Contents and Organization of the Physical
Activity Guidelines Advisory Committee Report
The report includes 3 major components. The first component provides
essential background and synthesis information:
- Part A: Report
Summary provides an executive summary of the entire
report.
- Part B:
Introduction provides a brief background on the formation of
the Physical Activity Guidelines Advisory Committee and the development of
their report.
- Part C: Key
Terms defines many of the major terms used throughout the
report, including those relating to physical activity, exercise, fitness,
health, and measurement.
- Part D:
Background provides context to the current guidelines
development effort by discussing some underlying concepts about physical
activity dose response, briefly describing recent physical activity trends
among Americans, and describing the development of previous physical activity
recommendations in the United States.
- Part E: Integration and
Summary of the Science synthesizes the Committee's findings
about the relation of physical activity to a broad array of health
outcomes.
- Part F: Scientific Literature
Search Methodology explains the development and use of the
Physical Activity Guidelines for Americans Scientific Database.
The second component, Part G: The
Science Base, includes 11 sections that review and summarize
the scientific literature relating physical activity to individual
health-related outcomes and populations: all-cause mortality, cardiorespiratory
health, metabolic health, energy balance, musculoskeletal health, functional
health, cancer, mental health, adverse events, youth, and understudied
populations.
The third component, Part H:
Research Recommendations provides a summary of the PAGAC's
collective recommendations about key areas of research that should be conducted
to further enhance the science base on physical activity and health.
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