This section of the Guidelines provides recommendations to pediatric care providers on physical activity relative to cardiovascular (CV) health in children and adolescents. The section begins with background information on the association between physical activity levels and cardiovascular disease. This is followed by the Expert Panel's summary of the evidence review of the association between physical activity and sedentary behavior and CV risk factors and the randomized controlled trials (RCTs) addressing behavior change relative to both physical activity and sedentary time. The evidence review and the Guidelines development processes are outlined in Section I. Introduction and are described in detail in Appendix A. Methodology. As described, the evidence review augments a standard systematic review where the findings from the studies reviewed constitute the only basis for recommendations, with each study described in detail. This evidence review combines a systematic review with an Expert Panel consensus process that incorporates and grades the quality of all relevant data based on preidentified criteria. Because of the large volume of included studies and the diverse nature of the evidence, the Expert Panel also provides a critical overview of the studies reviewed for each risk factor, highlighting those that, in its judgment, provide the most important information. Detailed information from each study has been extracted into the evidence tables and will be available at http://www.nhlbi.nih.gov/health-pro/guidelines/current/cardiovascular-health-pediatric-guidelines/index.htm. The conclusions of the Expert Panel's review of the evidence are summarized and graded, and the section ends with age-specific recommendations. Where evidence is inadequate, recommendations are a consensus of the Expert Panel. References are listed sequentially at the end of the section, with references from the evidence review identified by unique PubMed identifier (PMID) numbers in bold text. Additional references do not include the PMID number.
Physical activity is any bodily movement produced by contraction of skeletal muscle that increases energy expenditure above a basal level. Physical activity can be focused on strengthening muscles, bones, and/or joints, but because these Guidelines address CV health, the evidence review concentrated on aerobic activity. There is strong evidence for the beneficial effects of physical activity on the overall health of children and adolescents across a broad array of domains. In the United States, 16.6 percent of total deaths have been attributed to the combination of a sedentary lifestyle and dietary factors. The evidence review concentrated on the effects of physical activity on CV health where physical inactivity has been identified as an independent risk factor for coronary heart disease., Research on physical activity in children has explored three interdependent but distinct constructs: fitness, physical activity, and sedentary behavior. A comprehensive review of the independent role of each of these in CV health is beyond the scope of these Guidelines; specifically, the Expert Panel reviewed studies on physical activity and sedentary behavior but did not address research on fitness.
OVERVIEW OF THE EVIDENCE OF THE ASSOCIATION BETWEEN PHYSICAL ACTIVITY AND SEDENTARY BEHAVIOR AND CARDIOVASCULAR RISK FACTORS
Over the past several decades, there has been a decrease in the amount of time that children spend being physically active and a steady increase in the amount of time spent in sedentary activities. A recent systematic review indicates that contemporary youths watch 1.8?2.8 hours/day (h/d) of television, with 28 percent watching more than 4 h/d; boys average 60 minutes/day (min/d) playing video games compared with 23 min/d for girls; computer use increases with increasing age but averages 30 min/d across childhood. In this report, total screen time averaged 2.7?4.3 h/d. From the current evidence review, multiple observational studies in children ages 4?18 years and young adults ages 19?21 years strongly link increased time spent in sedentary activities with reduced overall physical activity levels; disadvantageous lipid profile changes; higher systolic blood pressure (BP); increased levels of obesity and all of the obesity-related CV risk factors, including hypertension, insulin resistance, and type 2 diabetes mellitus, especially among male children and adolescents. Participation in routine physical activity, including team sports, is inversely associated with these same outcomes.,,,,,,,
Longitudinal studies show that the most optimal CV risk profiles are seen in individuals who are consistently physically active.,, In diverse populations, the tracking of both sedentary and active behaviors is moderately strong from childhood to young adulthood, with the most consistent tracking seen for higher levels of physical activity at ages 9?18 years, predicting higher levels of adult physical activity.,,, Finally, health-enhancing and/or -compromising physical activity patterns, dietary choices, and smoking behaviors have consistently been shown to cluster together.,
OVERVIEW OF THE EVIDENCE FOR INTERVENTIONS TO INCREASE PHYSICAL ACTIVITY AND/OR DECREASE SEDENTARY TIME
The Guidelines evidence review identified 6 systematic reviews, 3 meta-analyses, and 46 RCTs addressing physical activity and/or sedentary behavior. Many studies simultaneously addressed increasing physical activity, decreasing sedentary behavior, and improving nutrition and measured fitness, obesity, lipid profile, BP, and/or insulin resistance as outcomes. More than a third of the identified RCTs were conducted in school settings and were designed as multicomponent interventions addressing combinations of the physical activity regimen, time spent in physical activity, environmental factors, and/or training of supervisors. Of the school-based trials, most were successful in increasing time spent being physically active and/or in decreasing sedentary time during the intervention in either or both sexes.,,,,,,,,,,,, Late followup after completion of an intervention is unusual, but when available, has not shown sustained physical activity change. School-based physical activity interventions have been shown to lower BP in children and adolescents and to decrease total cholesterol (TC).,, Such interventions occasionally have resulted in decreased measures of overweight and obesity,, but more often, school-based physical activity trials that have been designed to address measures of obesity have been unsuccessful.,,
Almost half of the physical activity RCTs have been relatively small studies in clinical research laboratory settings. Most were successful in increasing time spent being physically active and/or decreasing sedentary time during the intervention.,,,,,,,,,,,,,, Several RCTs demonstrated that making a favored sedentary activity contingent on increased physical activity was successful in increasing time spent being physically active and decreasing sedentary time,,,,,, and one study applied this concept successfully in an Internet-based physical activity-contingent intervention. Three of four studies set in daycare or community settings were successful in increasing physical activity and/or decreasing sedentary screen time.,, Finally, one successful study was implemented through a primary care practitioner's office that used computerized telephone and mailed reminders. Multiple physiologic outcomes were evaluated in these studies, many of which addressed prevention or treatment of obesity. The preponderance of the evidence indicates that increasing physical activity and decreasing sedentary time are associated with lower systolic and diastolic BP,,,,, decreased measures of body fat,,,,,,,,,,,, decreased body mass index (BMI) or percentage of overweight,,,,,, improved fitness measures,,,,,,,,,,,, lower TC,, lower low-density lipoprotein cholesterol (LDL?C), lower triglycerides (TG),,,, higher high-density lipoprotein cholesterol (HDL?C),, and decreased insulin resistance.,,,, Several studies in obese children have evaluated vascular function and have shown significant increases in flow-mediated dilation and reduced carotid intima-media thickness after exercise interventions.,,,,, No study reported any adverse CV outcome as a consequence of a physical activity intervention.
CONCLUSIONS AND GRADING OF THE EVIDENCE REVIEW FOR PHYSICAL ACTIVITY
Overall, the Expert Panel concluded that the evidence strongly supports the role of activity in optimizing CV health in children and adolescents.
- There is reasonably good evidence that physical activity patterns established in childhood are carried forward into adulthood (Grade C).
- There is strong evidence that increases in moderate to vigorous physical activity are associated with lower systolic and diastolic BPs, decreased measures of body fat, decreased BMI, improved fitness measures, lower TC, lower LDL?C, lower TG, higher HDL?C, and decreased insulin resistance in childhood and adolescence (Grade A).
- There is limited but strong and consistent evidence that physical exercise interventions improve subclinical measures of atherosclerosis (Grade B).
- Physical activity patterns, dietary choices, and smoking behaviors cluster together (Grade C).
- There is no evidence of harm associated with increased physical activity or limitation of sedentary activity in normal children (Grade A).
- There is strong evidence that physical activity should be promoted in schools (Grade A).
There is less specific information on the type and amount of physical exercise required for optimal CV health. Reported physical activity interventions from this evidence review ranged from 20 to 60 minutes, 2?5 times/week in children ages 3?17 years and included a wide variety of dynamic and isometric exercises. Extrapolating from these interventions which occurred in supervised settings to the real world of childhood and adolescence, the Expert Panel recommended at least 1 hour of moderate to vigorous physical activity every day of the week, with vigorous, intense physical activity on at least 3 of these days in agreement with the 2008 Physical Activity Guidelines for Americans from the U.S. Department of Health and Human Services. In working with children and families, the Expert Panel suggested that moderate to vigorous activity could be compared with walking briskly or jogging and that vigorous physical activity could be compared with running, playing singles tennis, or playing soccer. Similarly, reducing sedentary time is convincingly associated with a favorable CV profile, and the Expert Panel agreed with the recommendation from the American Academy of Pediatrics for limiting leisure screen time to no more than 1 to 2 hours of quality programming per day. The 2008 Physical Activity Guidelines for Americans was published after the evidence review for these Guidelines was completed and, therefore, cannot be formally included. However, the 2008 Physical Activity Guidelines is recommended to pediatric care providers as an extensive resource on physical activity recommendations for their patients and is available at http://ww.health.gov/paguidelines.
Pediatric care providers represent an important source of accurate information about physical activity recommendations for children and adolescents. However, information about how to optimize the adoption of these recommendations in a practice setting remains limited. The supportive actions included in Table 6?1 represent expert consensus suggestions from the Expert Panel to support implementation of the recommendations.
Table 6?1. Evidence-Based Physical Activity Recommendations for Cardiovascular Health
Grades reflect the findings of the evidence review.
Recommendation levels reflect the consensus opinion of the Expert Panel.
Supportive actions represent expert consensus suggestions from the Expert Panel provided to support implementation of the recommendations.
|0-12 months||Parents should create an environment promoting and modeling physical activity and limiting sedentary time|| Grade D
|0-12 months (cont.d)||Supportive actions:
|1- 4 years||Unlimited active playtime in safe, supportive environment|| Grade D
|1- 4 years (cont.d)||Limit sedentary time, especially TV/ video|| Grade D
|1- 4 years (cont.d)||Supportive actions:
|5 - 10 years||Moderate to vigorous physical activity* every day|| Grade A
|5 - 10 years (cont.d)||Limit daily leisure screen time (TV/video/computer)|| Grade B
|5 - 10 years (cont.d)||Supportive actions:
|11 -17 years||Moderate to vigorous physical activity* every day|| Grade A
|11 -17 years (cont.d)||Limit leisure time TV/video/computer use|| Grade B
|11 -17 years (cont.d)||Supportive actions:
|18 - 21 years||Moderate to vigorous physical activity* every day.|| Grade A
|18 -21 years (cont.d)||Limit leisure time TV/video/computer.|| Grade B
|18 -21 years (cont.d)||Supportive actions:
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