February 28 — 29, 2008 Advisory Committee Meeting Minutes

Youth Summary

Russell Pate, Ph.D., summarized the conclusions on integrated recommendations for youth.

Endurance training increases cardio-respiratory fitness among children and adolescents, males and females; however no conclusions can be made on race, ethnicity or SES. The data suggests endurance training increases VO2 max by 5 to 15%; however, the optimal dose of activity needed to obtain improvements cannot be specified. A recent review concluded that an intensity of greater than 80% of maximal heart rate with a frequency of 3 – 4 days per week for 30 – 60 minutes of duration over 1 – 3 months improves cardio-respiratory fitness. The data to support these conclusions consists of Type 1, 2, 3a and 3b, strong evidence.

Physical activity is positively related to muscular strength. Resistance training 2 or 3 times per week significantly improves muscular strength. Resistance training increases muscular strength in children and adolescents, males and females; however, the data cannot conclude anything on the effects by race, ethnicity or SES. The type of evidence to support the conclusions includes Type 2b, strong evidence.

Non-obese youth who have relatively high levels of physical activity tend to have less adiposity; however, programs that increase physical activity in normal weight youth typically have little effect on adiposity. Controlled training studies with overweight youth have observed reductions in overall adiposity and visceral adiposity with exposure to regular moderate-to-vigorous activity 3 – 5 times per week with duration of 30 – 60 minutes each. There is no consistent evidence for a dose-response pattern and no conclusions can be made on race, ethnicity or SES. These conclusions are supported by Type 2a, 2b, 3a, 3b, strong evidence.

Physical activity is positively related to cardiovascular and metabolic health in youth. There appears to be a dose-response relationship; however, the pattern has not been determined. Very little is known about the effects of age, maturity, gender, race, ethnicity and SES on the relationship between physical activity and cardiovascular and metabolic health. This is supported by Type 2a, 2b, 3a and 3b, strong, evidence.

Physical activity is positively related to bone health. Targeted weight loading activities that simultaneously influence muscular strength, done on a daily basis, are most effective. It is challenging to compare mode and dose due to variability across studies. No conclusions can be made on a dose-response relationship as more studies are needed. The relationship between physical activity and bone health is influenced by age and development status and the bone health of both boys and girls is improved by physical activity. No conclusions can be made regarding race, ethnicity and SES. The conclusions are supported by Type 1 and 3a, strong, evidence.

During childhood and adolescence, physical activity exerts a beneficial effect on symptoms of anxiety and depression. The varying methodologies and insufficient numbers of intervention trials preclude inferences about dose-response patterns. The research cannot support any conclusions regarding race, ethnicity or SES. Conclusions in the area of depression are supported by Type 1, 2b, 3a and 3b, moderate strength, evidence. Conclusions in the area of anxiety are supported by Type 1 and 3b, weak level of strength evidence.

Overall, important health benefits can be expected to accrue to most children and youth who participate daily in 60 or more minutes of moderate-to-vigorous physical activity. Regular participation in resistance exercise yields enhancement of muscular strength in the large muscle groups of the trunk and limbs. Vigorous aerobic exercise results in enhanced cardio-respiratory fitness and improved cardiovascular and metabolic health risk factors. Weight loading activities promotes bone health.

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