Percent body fat,but not body mass index,is associated with cardiometabolic risk factors in children and adolescents

Background:The epidemic of overweight and obesity has become a worldwide public health problem.Cardiometabolic diseases may originate in childhood.We investigated the association between percent body fat(PBF)measured by the bioelectrical impedance assay and cardiometabolic risk(CMR)in pediatrics.Methods:This cross-sectional study involved 3819 subjects(6-17 years old)in Shanghai.We assessed the association between PBF and body mass index(BMI)with multiple CMR factors.We examined the risk for cardiometabolic abnormalities attributable to overweight and obesity based on age-and sexspecific PBF Z-scores and BMI Z-scores,respectively.Results:PBF,but not BMI,was positively associated with multiple CMR factors in males and females except for total cholesterol in females(all p<0.05).Compared with the non-overweight group based on PBF,overweight and obese subjects had increasingly higher odds ratio of dyslipidemia(2.90(1.99-4.23),4.59(2.88-7.32)for males and 1.82(1.20-2.75),2.46(1.47-4.11)for females)and elevated blood pressure(BP)(3.26(2.35-4.51),4.55(2.92-7.09)for males and 1.59(1.07-2.34),3.98(2.27-6.17)for females).Obesity females showed a higher likelihood for hyperglycemia(2.19(1.24-3.84))than non-overweight females.In both sexes,the predictive effect of PBF on dyslipidemia and elevated BP in adolescents was better than that in children.For hyperglycemia,the predictive effect of PBF was better in male adolescents and female children.There was no risk difference for cardiometabolic abnormalities attributable to BMI-based obesity categories.Conclusions:PBF but not BMI was associated with CMR.Overweight and obesity categories based on PBF had an increased risk for cardiometabolic abnormalities in children and adolescents.

Effect of an Acute Exercise Session on Body Composition Using Multi-Frequency Bioelectrical Impedance Analysis in Adults

The purpose of this investigation was to examine the effect of an acute bout of aerobic exercise （AE） and resistance exercise （RE） on body composition measured by multi-frequency bioelectrical impedance analysis （MBIA） in adults. Ninety-five recreationally active young adults （46 women and 49 men） reported for testing on three occasions. After an initial MBIA assessment, subjects performed 45 minutes of continuous AE, RE, or did nothing, which served as the control （CON）. During the AE trial, subjects performed an acute bout of treadmill exercise at 60%-75% of their age predicted maximal heart rate （APHRmax）. The RE trial consisted of an 8-exercise circuit consisting of; 3 sets of 10-12 repetitions at 65%-75% of their one-repetition max （1RM） for each exercise. During the CON trial, subjects sat quietly in the laboratory. Body composition was reassessed immediately following the exercise bouts for comparison. Mean percent body fat （%BF） decreased following the exercise bouts （AE = 0.7%, RE = 1.6%; P 〈 0.001） likely due to significant （P 〈 0.001） reductions in impedance （AE： 40Ω, 32Ω, and 29Ω; RE： 4592, 29Ω, and 28Ω） measured at 5, 50 and 500 kHz. Conversely, significant increases in %BF （0.7%, P 〈 0.05）, body mass （0.2 kg, P 〈 0.001）, and impedance at 5 and 50 kHz （15Ω and 16Ω; P 〈0.001） were observed following the CON trial. These findings support that MBIA assessments should be performed prior to exercise in order to prevent exercise-induced reductions in %BF values.

Physical Activity and Body Composition Relate to Cardiorespiratory Fitness Independently in Young Adults with Down Syndrome

BACKGROUND： Persons with Down syndrome （DS） typically possess low cardiorespiratory fitness （CRF）, engage in low levels of physical activity （PA）, and display elevated obesity levels, but the association between these variables is not clear in persons with DS. METHOD： We investigated the relationships among measures of CRF, PA, and body composition in 30 young adults with DS （age： 21.3 ± 5.5 years） using a cross-sectional study design. RESULTS： Male participants presented on average with a BMI of 32.9 ± 10.0 kg/m2, a percent body fat of 22.2 ±13.0%, and a six-minute walk distance （6MWD） of 411.7 ± 66.3 m. Female participants presented on average with a BMI of 31.6 ± 13.5 kg/m2, a percent body fat of 26.7 ± 15.1%, and a six-minute walk distance （6MWD） of 360.4 ± 91.2 m. 6MWD shared a positive relationship with leisure time physical activity levels （r = 0.56, β = 1.488） and a negative relationship with body mass index （BMI; r = -0.49, β = -2.561）. No relationship between body composition and PA was found. CONCLUSIONS： It seems that higher PA levels and lower BMI relate to better CRF in young adults with DS. Physical activity and body composition appear to be unrelated in persons with DS.