December 6 — 7, 2007 Advisory Committee Meeting
Youth Subcommittee Report
Russell Pate, Ph.D., led the presentation from the Youth
Subcommittee. The subcommittee was comprised of Dr. Howley, Dr. Yancey along
with Steve Daniels, Chris Economos, Bob Gutin and Bog Malina as consultants. The
CDC liaisons were Jackie Epping and Janet Fulton. The questions posed by the
Among children and youth, is physical activity significantly
related to body mass and composition, the metabolic syndrome, physical
fitness, specifically cardio-respiratory fitness, muscular strength, mental
health and bone health?
If there is a relationship is there a dose-response pattern?
Does age, gender or socio-economic status influence the
This area poses a large issue because the group is looking at
many different outcomes and youth do not manifest themselves as a single group
from a research perspective.
In terms of body mass composition a total of 104 studies were
identified with varied designs. While there are complications in interpreting
data from different study designs modest reductions in adiposity can be linked
to physical activity. In general, 30 to 60 minutes of aerobic activity performed
3 to 5 times a week showed benefits.
For the metabolic syndrome, 41 studies were identified.
Observational studies show that youth with high levels of physical activity have
more favorable risk profiles. There is a clearer association in boy then in
girls for insulin sensitivity. Some studies suggest that 360 minutes or 60
minutes per day, 6 days per week of moderate to vigorous activity shows
beneficial impact on the metabolic syndrome.
Researching the relationship with regards to physical fitness,
specifically cardio-respiratory fitness and muscular strength and endurance
resulted in 34 studies. The studies consistently concluded that endurance
training does produce increases in maximal aerobic power across both genders.
Similarly, resistance training shows benefits in muscular strength.
The areas within mental health that were looked at include
anxiety, academic performance, achievement, cognition, intelligence and
self-perception. Tentatively, the group's findings show weak, inverse
associations between activity and depression and anxiety. There is both little
data and inconclusive data on the relationship on academic performance.
With regards to bone health, 29 studies were reviewed. From the
data it appears there are positive effects of physical activity for bone
mineralization. Conversely, there is a sense that physical inactivity during
adolescence may result in children failing to meet their full potential for peak
Finally, a compelling question is whether early patterns of
activity during childhood influence health outcomes later in life. Currently,
there is little literature on this point.