The heart challenge: The effect of regular aerobic exercise on body fat distribution in third and fourth grade school children: A randomized clinical trial

The pattern of body fat distribution known as centralized , and characterized by a predominance of subcutaneous fat on the trunk and a pot belly , has been associated with an increased risk of chronic disease. These patterns of fat distribution, as well as the lifestyle habit variables associated with adult fatness and chronic morbidity clearly begin to develop during childhood, indicating the need for intervention and primary prevention of obesity, particularly the centralized form, during childhood or adolescence. The purpose of this study was to determine whether regular aerobic exercise could beneficially alter the distribution of body fat in 8 and 9 year old children. One hundred and eighty-eight participants were randomized into either a regular aerobic exercise treatment group or a standard physical education program control group. A variety of aerobic activities was used for intervention 5 days per week during physical education class for a period of 12 weeks. Fat distribution was measured by a number of the most commonly used indices, including ratios of body circumferences and skinfolds and indices derived from a principal components analysis. Change over time in average pulse rate was used to determine if intervention actually occurred. Approximately 10% of the students were remeasured, allowing the calculation of intra- and interexaminer measurement reliability estimates for all indices.^ This study group was comparable to the U.S. population, though the study children were slightly larger for certain measures. No effect of the exercise intervention was found. The most likely explanation for this was inadequacy of the intervention, as indicated by the lack of any change in average pulse rate with treatment. The results of the measurement reliability analysis are reported and indicate that body circumference ratios are more precise than skinfold ratios, particularly when multiple observers are used. Reliability estimates for the principal component indices were also high.^ It remains unclear whether the distribution of body fat can be altered with exercise. It is likely that this issue will remain undecided until one highly reliable, valid, and sensitive measure of fat distribution can be found.

Serial and Parent-Child Changes in Components of Body Fat Distribution and Fatness in Children from the London Longitudinal Growth Study, Ages Two to Eighteen Years

Previous studies have been done tracking individual changes in subcutaneous fat from childhood, but none of these studies has clearly examined the patterns of anatomical fat distribution. In addition, previous research has suggested that 20 to 30% of the variance in young adults is due to genetic influences. But again, there are few studies that have addressed the distribution of fat, particularly in children. The objective of this study was to examine whether there is a stronger genetic influence on an individual’s patterns of distribution of subcutaneous fat than on an individual’s overall fatness, as evidenced by 1) stronger age to age correlations, 2) stronger later age to previous age correlations and 3) stronger parent-child correlations for fat patterning as compared to the same correlations for overall fatness. A principal components analysis was used to construct components of body fat distribution, and the trunk-extremity and upper-lower body contrasts of skinfold sites appeared, as they have in previous studies. W hen the three sets of correlations described above were calculated for fat patterning and overall fatness, the only instance in which the correlations for fat patterning were consistently higher than those for overall fatness was for the self-correlations in girls. Parent-child correlations for fat patterning components vary more than those for overall fatness, and are generally higher between mothers and their children than between fathers and their children

Sensitivities, Specificities, and Positive Predictive Values ofSimple Indices of Body Fat Distribution

Centralized obesity has been associated with increased risk of non-insulin dependent diabetes and cardiovascular disease. Paramount to a sensitive index of body fat distribution is that it contain a measure of lower limb fat (Ashwell et al. 1978; 1982; Mueller and Stallones 1981). However, many epidemiological studies of body fat distribution, which have used skinfold measurements, have been limited to estimating centralized obesity from the triceps and subscapular or other conventional upper body sites. The purpose of this study was to evaluate the sensitivities, specificities, and positive predictive values of skinfold indices of body fat distribution when only sites on the upper body are available. We were able to do this in a large population-based data set, the Canadian YMCA-LIFE study, which in­cluded adults 25 to 64 years of age and skinfold sites from upper and lower anatomical regions of the body.Sensitivities, specificities, and positive predictive values did not vary systematically with age group, sex or obesity level. Sensitivities (mean = 70%) and positive predictive rates (mean = 65%) were moderate for the most common two site index (triceps/triceps + subscapular) and were not notably improved with the addition of the suprailiac site. Simple percent extremity fat indices (e.g. triceps/(triceps + subscapular) X 100) were as effective in discriminating body fat distribution groups as an index involving the same variables in the form of a vector of log transformed measurements. Substituting lower limb fat (medial calf) for arm fat (triceps) in simple percent indices, provided important additional information (mean sen­sitivity = 77%, mean positive predictive rate = 70%)

Epidemiologic study of cystic fibrosis: Design and implementation of a prospective, multicenter, observational study of patients with cystic fibrosis in the U.S. and Canada

Cystic fibrosis (CF) is a complex illness characterized by chronic lung infection leading to deterioration in function and respiratory failure in over 85% of patients. An understanding of the risk factors for that progression and the interaction of these factors with current therapeutic strategies should materially improve the prevention of this progressive lung disease. The Epidemiologic Study of Cystic Fibrosis (ESCF) was therefore designed as a multicenter, longitudinal, observational study to prospectively collect detailed clinical, therapeutic, microbiologic, and lung function data from a large number of CF treatment sites in the U.S. and Canada. The ESCF also serves an important role as a phase‐IV study of dornase alfa. To be eligible for enrollment, subjects must have the diagnosis of CF and receive the majority of their care at an ESCF site. In this paper, the authors present the ESCF study design in detail. Further, enrollment data collected at 194 study sites in 18,411 subjects enrolled from December 1, 1993 to December 31, 1995 are presented in summary form. This comprehensive study is unique in the detail of clinical data collected regarding patient monitoring and therapeutic practices in CF care. Two companion articles present data regarding practice patterns in cystic fibrosis care, including data on resource utilization and prescribing practices. Pediatr Pulmonol. 1999; 28:231–241. © 1999 Wiley‐Liss, Inc