Relations of Body Fatness and Cardiovascular Fitness to Lipid Profile in Black and White Adolescents

Abstract

High body fatness is associated with unfavorable cardiovascular disease risk profiles in juveniles. However, the degree to which the deleterious effects attributed to fatness may actually be due to the low cardiovascular fitness (CVF) that is usually confounded with fatness is not known. This study determined in 14-to 18-y-old (n ϭ 398) youths the degree to which percentage body fat (%BF) and CVF explained variability in lipids and lipoproteins. Blood samples were taken after a 12-h fast. %BF was measured with dual-energy x-ray absorptiometry. CVF was determined with a multistage treadmill test. The degree to which %BF and CVF explained variance in outcome variables was determined by regression analyses, controlling for demographic variables before entering %BF or CVF and their interactions with race and sex. Because %BF and CVF were highly correlated (r ϭ -0.69, p Ͻ 0.001), they were first entered separately in the regression models before being considered together. Both higher %BF and lower CVF were associated with unfavorable concentrations of total cholesterol to HDLC ratio and triglycerides. However, the effects of %BF and CVF were not additive; once %BF was in the regression model, CVF did not explain additional variance. For Lp(a), only %BF explained a significant portion of the variance. For triglycerides, there was a %BF by race interaction, such that the deleterious effects of high %BF were greater in whites than in blacks. These results suggest that interventions to improve lipid profile in youths should be designed primarily to minimize fatness. Pathophysiologic processes underlying CVD begin in childhood (1,2), suggesting that preventive measures should begin early in life. Observational studies have shown that childhood adiposity is associated with an unfavorable lipid profile (3,4), which continues into adulthood (4). However, less is known about the role of CVF. Because of the strong inverse correlation between CVF and fatness (5), it is possible that deleterious consequences ascribed to adiposity may be partially due to the influence of low CVF, which is frequently unmeasured. If so, it would imply that interventions to prevent unfavorable lipid profiles should focus on CVF as well as adiposity. In adults, both fatness and fitness predict future mortality (6); in fact, the effects of CVF may even be more robust than the effects of fatness (7). There is some recent evidence that both fatness and fitness are related to unfavorable CVD risk factor status in youths (8).Another issue concerns the degree to which the relations are similar for different races and sexes. We recently reported that the deleterious consequences on insulin levels of high fatness and low fitness are more clearly seen in boys than in girls (5). With respect to lipid profile, there is some evidence that the deleterious consequences of excess adiposity are clearer in white than in black youths (9), but little is known about the degree to which this is also true for CVF.

Influence of Aerobic Power and Percent Body Fat on Cardiovascular Disease Risk in Youth

“…We found that percent fat was highly correlated with each risk factor separately, in agreement with previous studies [1,6,11]. The influence of percent fat was also evident in the inverse correlations among fat and kgVO 2 max present in every age group.…”

“…Which variable, fitness or fatness, is more important in determining CVD risk in youth is still controversial. Research has shown that a higher percent body fat is associated with increased CVD risk factors in youth, regardless of fitness levels [1,5,11]. Similarly, fatness has been associated with elevations in BP [1,4 -7,9], some blood lipids [1,4,6,11], and insulin [5][6][7].…”

Body mass index and waist circumference in midchildhood and adverse cardiovascular disease risk clustering in adolescence

“…The results of our study are consistent with a small number of pediatric cross-sectional studies (4,15,16). We are not aware of any other longitudinal studies that have examined the effects of an increased waist circumference in childhood on CVD risk clustering in adolescence.…”

A massa gorda de risco afeta a capacidade aeróbia de jovens adolescentes

“…Esta observação é concordante com as de outros estudos mais recentes 19,[26][27][28] que reportam a existência de forte correlação entre a capacidade aeróbia e diversas medidas de avaliação da massa gorda em crianças e adolescentes, principalmente em sujeitos com %MG correspondentes aos grupos de risco (moderado e elevado).…”