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Educating the Student Body
loss of 5-10 percent of body weight through calorie restriction and exercise 
has been shown to reduce the risk of cardiometabolic disease by improv-
ing risk factors (Diabetes Prevention Program Research Group, 2002; 
Ross and Janiszewski, 2008). In particular, weight loss results in reduced 
visceral adipose tissue, a strong correlate of risk (Knowler et al., 2002), 
as well as lower blood pressure and blood glucose levels due to improved 
insulin sensitivity. Even without significant weight loss, exercise can have 
significant effects in adults by improving glucose metabolism, improving 
lipid and lipoprotein profiles, and lowering blood pressure, particularly for 
those who are significantly overweight (Ross and Bradshaw, 2009). Similar 
benefits have been observed in adolescents.
A growing body of literature addresses the associations of physical 
activity, physical fitness, and body fatness with the risk of metabolic syn-
drome and its components in children and especially adolescents (Platat 
et al., 2006; McMurray et al., 2008; Rubin et al., 2008; Thomas and 
Williams, 2008; Christodoulos et al., 2012). Studies in adults have shown 
that higher levels of physical activity predict slower progression toward 
metabolic syndrome in apparently healthy men and women (Laaksonen 
et al., 2002; Ekelund et al., 2005), an association that is independent of 
changes in body fatness and cardiorespiratory fitness (Ekelund et al., 2007). 
Few population studies have focused on these relationships in children 
and adolescents, and the use of self-reported activity, which is imprecise in 
these populations, tends to obscure associations. In a large sample of U.S. 
adolescents aged 12-19 in the 1999-2002 NHANES, for example, there 
was a trend for metabolic syndrome to be more common in adolescents 
with low activity levels than in those with moderate or high activity levels, 
although the differences among groups were not statistically significant 
(Pan and Pratt, 2008). Moreover, for each component of metabolic syn-
drome, prevalence was generally lower with higher physical activity levels, 
and adolescents with low physical activity levels had the highest rates of all 
metabolic syndrome components.
The association between cardiorespiratory fitness and metabolic syn-
drome also was examined in the 1999-2002 NHANES (Lobelo et al., 
2010). Cardiorespiratory fitness was measured as estimated peak oxygen 
consumption using a submaximal treadmill exercise protocol, and meta-
bolic syndrome was represented as a “clustered score” derived from five 
established risk factors for cardiovascular disease, an adiposity index, insu-
lin resistance, systolic blood pressure, triglycerides, and the ratio of total 
to HDL cholesterol. Mean clustered risk score decreased across increasing 
fifths (quintiles) of cardiorespiratory fitness in both males and females. The 
most significant decline in risk score was observed from the first (lowest) 
to the second quintile (53.6 percent and 37.5 percent in males and females, 
respectively), and the association remained significant in both overweight 

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Copyright © National Academy of Sciences. All rights reserved.
Educating the Student Body: Taking Physical Activity and Physical Education to School
Relationship to Growth, Development, and Health
 
127
and normal-weight males and in normal-weight females. Other studies, 
using the approach of cross-tabulating subjects into distinct fitness and 
fatness categories, have examined associations of fitness and fatness with 
metabolic syndrome risk (Eisenmann et al., 2005, 2007a,b; Dubose et al., 
2007). Although different measures of fitness, fatness, and metabolic syn-
drome risk were used, the results taken together across a wide age range 
(7-18) show that fitness modifies the influence of fatness on metabolic syn-
drome risk. In both males and females, high-fit/low-fatness subjects have 
less metabolic syndrome risk than low-fit/high-fatness subjects (Eisenmann, 
2007).
That many adult chronic health conditions have their origins in child-
hood and adolescence is well supported (Kannel and Dawber, 1972; Lauer 
et al., 1975; Berenson et al., 1998; IOM, 2004). Both biological (e.g., 
adiposity, lipids) and behavioral (e.g., physical activity) risk factors tend to 
track from childhood and especially adolescence into adulthood. Childhood 
BMI is related to adult BMI and adiposity (Guo et al., 1994, 2000; 
Freedman et al., 2005), and as many as 80 percent of obese adolescents 
become obese adults (Daniels et al., 2005). Coexistence of cardiometabolic 
risk factors, even at young ages (Dubose et al., 2007; Ramírez-Vélez et al., 
2012), has been noted, and these components of metabolic syndrome also 
have been shown to track to adulthood (Bao et al., 1994; Katzmarzyk et 
al., 2001; Huang et al., 2008). Landmark studies from the Bogalusa Heart 
Study (Berenson et al., 1998; Li et al., 2003) and others (Mahoney et al., 
1996; Davis et al., 2001; Morrison et al., 2007, 2008) have demonstrated 
that cardiometabolic risk factors present in childhood are predictive of 
adult disease. 
The benefits of exercise for prevention and treatment of cardio-
metabolic disease in adults are well described (Ross et al., 2000; Duncan et 
al., 2003; Gan et al., 2003; Irwin et al., 2003; Lee et al., 2005; Sigal et al., 
2007; Ross et al., 2012). Prospective studies examining the effects of exer-
cise on metabolic syndrome in children and adolescents remain limited, and 
it is important to refrain from extrapolating intervention effects observed in 
adults to youth, although one might reasonably assume the benefits in older 
adolescents to be similar to those in young adults. Indeed, based on the 
inverse associations of physical activity and physical fitness with metabolic 
syndrome (Kim and Lee, 2009) and on the available intervention studies, 
some experts have recommended physical activity as the main therapeutic 
tool for prevention and treatment of metabolic syndrome in childhood 
(Brambilla et al., 2010). Comparative studies in adults have shown that the 
effect of exercise on weight is limited and generally less than that of calorie 
restriction (Brambilla et al., 2010). Moreover, the relative effectiveness of 
diet and exercise depends on the degree of excess fatness (Brambilla et al., 
2010). Comparative studies in children and youth are few, as behavioral 

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Educating the Student Body: Taking Physical Activity and Physical Education to School
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