The inflammatory score and cardiovascular risk in young adults with overweight or obesity: The African-PREDICT study

OBJECTIVES

A complex relationship of adipokines and cytokines with cardiovascular risk motivates the use of an integrated approach to identify early signs of adiposity-related inflammation. We compared the inflammatory profiles, including an integrated inflammatory score, and cardiovascular profiles of young adults who are living with overweight and/or obesity (OW/OB).

DESIGN AND METHODS

This cross-sectional study included 1194 men and women with a median age of 24.5 ± 3.12 years from the African Prospective study on the Early Detection and Identification of Cardiovascular disease and Hypertension (African-PREDICT). Participants were divided into approximate quartiles based on adiposity measures (body mass index, waist circumference, and waist-to-height ratio). We compared an integrated inflammatory score (including leptin, adiponectin, interleukin-6, interleukin-8, interleukin-10, and tumour necrosis factor-α) as well as the individual inflammatory markers, between extreme quartiles. We also compared blood pressure measures, left ventricular mass index, carotid-femoral pulse wave velocity, and carotid intima-media thickness between these groups.

RESULTS

Individuals in the top quartile had worse inflammatory- and cardiovascular profiles as the integrated inflammatory score, leptin, interleukin-6, blood pressure measures, and left ventricular mass index were higher, while adiponectin was lower (all p ≤ 0.003). Unexpectedly, carotid-femoral pulse wave velocity was also lower (p < 0.001) in the top quartile. Exclusively in the top quartile, all adiposity measures related positively with the integrated inflammatory score and central systolic blood pressure (both r ≥ 0.24; p < 0.001), and negatively with interleukin-10 (all r ≤ -0.13; p < 0.03). Of these relationships, the correlations with the integrated inflammatory score were the strongest (p < 0.001). The percentage difference of being in the top quartile of all adiposity measures were higher for the inflammatory score (all ≥ 263 %), leptin (all ≥ 175 %), interleukin-6 (all ≥ 134 %), and tumour necrosis factor-α (all ≥ 26 %), and lower for adiponectin (all ≥ 57 %), interleukin-10 (all ≥ 9 %), and interleukin-8 (all ≥ 15 %) compared to being in the bottom quartile.

CONCLUSION

The inflammatory score, as a comprehensive marker of adiposity-related inflammation, is strongly related to adiposity and may be an indication of early cardiovascular risk in young adults; however, further work is required to establish the clinical use thereof.

Arterial stiffness as a measure of cardiovascular risk in obese adolescents and adolescents with diabetes type 1

Background Cardiovascular disease (CVD) is the end result of vascular aging and atherosclerosis, having its origins in childhood. The aim of our study was to compare arterial stiffness (AS) and intima-media thickness (IMT) as markers of an early vascular damage between obese adolescents, adolescents with diabetes type 1 (T1D) and lean control subjects. Methods We analyzed AS and IMT in 68 obese adolescents (13.27±2.31 years), 42 adolescents with T1D (14.95±2.35 years) lasting over 5 years and 38 controls (15.02±1.94 years). AS (measured by pulse wave velocity [PWV], arterial compliance [AC] and β-stiffness) and IMT were assessed using an e-tracking ultrasound method. Results A significant difference between the groups was found for AC (p=0.022) and PWV (p=0.010), with the lowest compliance and higher velocities in T1D patients. When corrected for age, the difference in AC among the groups did not reach a statistical difference (p=0.059). Correlation analysis in the obese adolescents showed lower AC in females (p=0.041), with higher systolic blood pressure (SBP) (p=0.032). In T1D adolescents, disease duration was the strongest determinant of AS (AC p=0.028, β p=0.029 and PWV p=0.003), followed by body mass index (BMI; PWV p=0.008; β p=0.033), SBP (AC p<0.001; PWV p=0.023), diastolic BP (AC p=0.049; PWV p=0.048) and HbA1c (PWV p=0.048). No significant correlations were found for AS measures or IMT with sex, age, BMI, Tanner stage or BP levels in controls. Conclusions Early vascular damage is more pronounced in T1D adolescents than in obese or lean adolescents, which may emphasize the impact of hyperglycemia as a major threat for cardiovascular health.

Peripheral and Central Aortic Pressure, Wave-Derived Reflection Parameters, Local and Regional Arterial Stiffness and Structural Parameters in Children and Adolescents: Impact of Body Mass Index Variations

AIM

The aim was to analyze and compare the associations between body mass index (BMI) and structural and functional cardiovascular variables measured in children and adolescents.

METHODS

609 healthy subjects (mean age/range 12/4-18 years, 45% females) were studied. Subjects' BMI and the corresponding z-scores (z-BMI) were determined. Cardiovascular measurements: peripheral and aortic blood pressure (BP), aortic wave-derived parameters, common carotid, femoral and brachial artery diameters and stiffness, carotid intima-media thickness, carotid-radial and carotid-femoral pulse wave velocity (crPWV, cfPWV) and cfPWV/crPWV ratio. Cardiovascular data were standardized (z-scores) using equations (fractional polynomials) obtained from a sub-group (reference population, n = 241) non-exposed to cardiovascular risk factors (CVRFs). Simple and multiple regression models were obtained for the associations between cardiovascular z-scores and z-BMI and/or z-BMI, age, sex and CVRFs.

RESULTS

z-BMI was associated with standardized cardiovascular variables, regardless of age, sex and CVRFs. BP (peripheral rather than aortic) was the variable with the greatest variations associated with z-BMI. Systolic (SBP) and pulse pressure (PP; in that order) were the variables with the highest variations associated with z-BMI. Carotid, but not femoral or brachial stiffness showed BP-dependent variations associated with z-BMI. Arterial diameters were associated with z-BMI, without differences among arteries.

CONCLUSION

In children and adolescents, z-BMI was gradually and positively associated with haemodynamic (peripheral and central BP) and vascular parameters (structural and functional) with independence of age, sex and other CVRFs (Dyslipidemia, Hypertension, Smoke, Diabetes). There were differences in the associations depending on the arteries studied and on whether central or peripheral haemodynamic parameters were analyzed.

Effects of Obesity and Hypertension on Pulse Wave Velocity in Children

Pulse wave velocity (PWV) is a biomarker of arterial stiffness. Findings from prior studies are conflicting regarding the impact of obesity on PWV in children. The authors measured carotid-femoral PWV in 159 children aged 4 to 18 years, of whom 95 were healthy, 25 were obese, 15 had hypertension (HTN), and 24 were both obese and hypertensive. Mean PWV increased with age but did not differ by race or sex. In adjusted analyses in children 10 years and older (n=102), PWV was significantly higher in children with hypertension (PWV±standard deviation, 4.9±0.7 m/s), obesity (5.0±0.9 m/s), and combined obesity-hypertension (5.2±0.6 m/s) vs healthy children (4.3±0.7 m/s) (each group, P<.001 vs control). In our study, obesity and HTN both significantly and independently increased PWV, while African American children did not have a higher PWV than Caucasian children.

Determinants of carotid-femoral pulse wave velocity in prepubertal children

BACKGROUND

Pulse wave velocity (PWV) is a noninvasive technique to evaluate arterial stiffness, a dynamic property of the vessels, reflecting their structure and function. Childhood obesity is associated with several cardiovascular comorbidities and to the progression of atherosclerosis. We aimed to compare carotid-femoral PWV between normal weight and overweight/obese prepubertal children and to quantify its association with other cardiovascular risk factors.

METHODS

Cross-sectional study of 315 children aged 8-9years. Anthropometrics, 24-h ambulatory blood pressure (BP) and carotid-femoral PWV were measured. Classification of obesity was according to World Health Organization (WHO) body mass index (BMI)-for-age reference values.

RESULTS

Compared to normal weight children, overweight and obese children presented significantly higher levels of PWV (4.95 (P25-P75: 4.61-5.23), 5.00 (4.71-5.33), 5.10 (4.82-5.50) m/s, respectively; ptrend<0.001). Significant positive correlations were found between PWV and total cholesterol, LDL cholesterol, triglycerides, fasting insulin and insulin resistance levels (HOMA-IR) and with high-sensitivity C-reactive protein (hs-CRP). In a multivariate linear regression model adjusted for sex, age, height and 24-h systolic blood pressure z-score, the independent determinants of PWV were BMI, HOMA-IR and the absence of dipping.

CONCLUSIONS

The association between PWV and the loss of dipping and insulin resistance levels, independently of the BMI, reinforces the contribution of these comorbidities to vascular injury in early life.

Influence of obesity in central blood pressure

BACKGROUND

Obesity is an important risk factor for cardiovascular disease and has become a major concern in healthcare due to its high prevalence worldwide. The aim of the present study was to investigate the impact of BMI on central blood pressure (BP) and pulse wave velocity (PWV) in normotensive and hypertensive patients.

PATIENTS AND METHODS

Normotensive and hypertensive adult patients who attended the outpatient clinic of cardiovascular risk were included. Peripheral BP was obtained in the brachial artery by using an oscillometric device (OMRON M-6). Central aortic BP waveform was reconstructed from the radial artery pressure waveforms (SphygmoCor, AtCor Medical, Sydney, Australia) and central BP was calculated. Carotid-femoral PWV was measured by an automatic device (Complior, Artech, France).

RESULTS

We examined a total of 351 patients [50.7% women; 77 patients normal-weight (BMI < 25 kg/m)], 274 patients overweight or obese (BMI ≥25 kg/m). Central SBP showed a positive association with male sex and mean BP, but a negative association with overweight/obesity. PWV was positively associated with age, male sex, central BP, peripheral BP and BP treatment, whereas BMI of at least 25 kg/m led to a decrease in PWV in patients with the same central SBP levels. Likewise, PWV was lower in the overweight/obese group compared to the normal-weight group at the same central SBP.

CONCLUSION

Overweight and obesity tend to have lower central SBP as compared to lean patients, mainly in women. Further research is required to assess the interaction between body weight and vascular dynamics and their clinical implications.

Intima-media thickness and arterial function in obese and non-obese children

Background

Obesity is an independent cardiovascular risk factor that contributes to the development of atherosclerosis. Subclinical forms of the disease can be assessed via sonographic measurement of carotid intima-media thickness (cIMT) and distensibility – both may already be altered in childhood. As childhood obesity increases to an alarming extent, this study compares vascular data of obese with normal weight boys and girls to investigate the influence of obesity on cIMT and distensibility of the carotid arteries.

Methods

cIMT and distensibility of 46 obese children (27 girls) aged 7–17 years were compared with measures of 46 sex- and age-matched normal weight controls. cIMT and distensibility were measured by B- and M-mode ultrasound and expressed as standard deviation scores (SDS). Arterial distensibility was defined by arterial compliance (AC), elastic modulus (Ep), stiffness index β (β), and local pulse wave velocity β (PWV β).

Results

Obese girls had significantly stiffer arteries compared with normal weight girls (Ep SDS 0.64 ± 1.24 vs. 0 ± 1.06, β SDS 0.6 ± 1.17 vs. -0.01 ± 1.06 p < .01, PWV β 0.54 ± 1.2 vs. -0.12 ± 1.05 p < .05). No significant differences were observed for boys. In multiregression analysis, BMI significantly influenced Ep, β and PWV β but not cIMT and AC.

Conclusions

Obese girls seemed to be at higher cardiovascular risk than boys, expressed by stiffer arteries in obese girls compared with normal weight girls. Overall, BMI negatively influenced parameters of arterial stiffness (Ep, β and PWV β) but not compliance or cIMT.

Arterial compliance in obese children: implications for cardiovascular health

Recent work showed that arterial compliance may be elevated unexpectedly in obese children, attributable to accelerated growth and maturation. We hypothesize that children with obesity or Type 2 diabetes may reach peak arterial maturation earlier in life and then experience an earlier, and potentially more rapid, decline in arterial compliance, leading toward earlier cardiovascular disease development.

Arterial elasticity in obese adolescents with clinical features of insulin resistance

OBJECTIVE

To determine whether arterial elasticity differs between obese adolescents with clinical insulin resistance (IR), type 1 diabetes (T1D) and healthy non-obese controls.

METHODS

This cross-sectional study evaluated 69 adolescents with clinical IR, 91 with T1D and 63 age-matched (10- to 18-year-old) controls. Arterial elasticity was measured using radial tonometry pulse-wave analysis. Stepwise multiple regression analyses were performed to assess the determinants of the small and large arterial elasticity indices (SAEI and LAEI).

RESULTS

SAEI and LAEI raw values were higher in the IR group than the controls, and these did not differ between the T1D and control groups. Weight and diastolic blood pressure (DBP) were significant predictors of SAEI. After adjustment for weight and DBP, SAEI decreased by 0.65 mL/mmHg × 100 for each 1-year increase in age in the IR group. SAEI was not different across the groups after controlling for weight and DBP. Height was the strongest predictor of LAEI which remained higher in the IR group after controlling for height and blood pressure.

CONCLUSION

Obese adolescents with clinical IR have a higher SAEI, which declines with age; this may reflect a pathway to an increased risk of premature cardiovascular disease.

Sex and race (black-white) differences in the relationship of childhood risk factors to adulthood arterial stiffness: the Bogalusa Heart Study

BACKGROUND

Cardiovascular risk factors in childhood are predictive of adulthood arterial stiffness. However, it is unknown whether this relationship varies by race or sex.

METHODS

Six hundred and eighty adults aged 24 to 43 had been followed for an average of 26.3 years, from the Bogalusa Heart Study. Brachial to ankle pulse wave velocity (baPWV) measured by an automatic oscillometric technique was used as the outcome variable for arterial stiffness during adulthood. Body mass index (BMI), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), glucose, and systolic blood pressure (SBP), all measured in childhood, were used as predictors. The average values of childhood measurements at multiple time points were used, standardized to age, race, and sex-specific z-scores.

RESULTS

In the total sample, childhood SBP was the only significant predictor (P < 0.001) for adult baPWV. Significant interactions between sex and BMI (P = 0.001), between sex and LDL-C (P = 0.035), and between race and HDL-C (P = 0.002) on adult baPWV were identified. Childhood predictors of adult baPWV were BMI (30.9 cm/s reduction in baPWV per standard deviation increase, 95% confidence interval [CI]: -55.0, -6.9 cm/s), LDL-C (30.8 cm/s increase, 95% CI: 2.9, 59.5 cm/s), and HDL-C (46.8 cm/s reduction, 95% CI: -76.2, -17.4 cm/s) in white males; SBP (38.2 cm/s increase, 95% CI: 11.0, 65.4 cm/s) in white females; BMI (71.3 cm/s reduction, 95% CI: -119.9, -22.7 cm/s) in black males; and none in black females.

CONCLUSIONS

The associations of childhood cardiovascular risk factors with adult arterial stiffness varied by race and sex.

Vascular compliance in lean, obese, and diabetic children and adolescents: a cross-sectional study in a minority population

BACKGROUND

In adults, both obesity and type 2 diabetes mellitus (T2DM) are positively correlated with cardiovascular disease mortality and arterial stiffness. Several studies of adults have shown that both obesity and T2DM are independently associated with increased arterial stiffness. However, little is known about the relationship between arterial compliance and cardiovascular disease risk in children. We assessed whether large and small arterial compliance is impaired in obese and diabetic pubertal children.

METHODS

One hundred children of African-Caribbean ethnicity, aged 14-16 years, including 21 lean children (between the 25th and 75th percentile), 40 obese children (>95th percentile), and 39 children with T2DM diagnosed by American Diabetes Association criteria were studied. Arterial compliance of the large (C1) and small (C2) vessels was measured using radial arterial diastolic pulse wave contour analysis.

RESULTS

C1 did not differ significantly between lean, obese, and T2DM subjects. C2 was significantly greater in obese and T2DM subjects (10.9 ± 1 and 10.4 ± 0.7 ml/mm Hg × 100 ml, respectively) compared to lean subjects (7.8 ± 0.8 ml/mm Hg × 100 ml; p < 0.05). C2 was also significantly greater in T2DM subjects receiving antihypertensive drug therapy than in diabetic subjects not on antihypertensive treatment.

CONCLUSION

Increased compliance in diabetic and obese children compared to lean subjects could be secondary to premature maturation of the vascular system; whether this early maturation can translate into a subsequent rise in the incidence of cardiovascular events related to diabetes and obesity can only be determined by long-term follow-up of these patients.

Impact of pubertal development on endothelial function and arterial elasticity

OBJECTIVES

Little is known about the relation of pubertal development on endothelial function and arterial elasticity in children and adolescents; therefore, we compared brachial artery flow-mediated dilation and carotid artery elasticity across Tanner (pubertal) stages in children and adolescents.

STUDY DESIGN

Blood pressure, fasting lipids, glucose and insulin, body fat, insulin sensitivity adjusted for lean body mass, brachial flow-mediated dilation (percent dilation and area under the curve), endothelium-independent dilation (peak dilation and area under the curve), and carotid artery elasticity were evaluated across pubertal stages (Tanner I vs Tanner II-IV vs Tanner V) in 344 children and adolescents (184 males, 160 females; ages 6 to 21 years).

RESULTS

One hundred twenty-four subjects (mean age 8.23 ± 0.15 years; 52 females) were Tanner stage I; 105 subjects (mean age 13.19 ± 0.17 years; 47 females) were Tanner stages II-IV; and 115 subjects (mean age 17.19 ± 0.16 years; 61 females) were Tanner stage V. There were no significant differences for any of the measures of vascular structure and function across pubertal stages.

CONCLUSION

Results of the current study indicate that smooth-muscle and endothelial function, as well as carotid artery elasticity, do not differ throughout pubertal development and that accounting for pubertal stage when reporting vascular data in children and adolescents may be unnecessary.

Relationships between emerging cardiovascular risk factors, z-BMI, waist circumference and body adiposity index (BAI) on adolescents

OBJECTIVE

The body adiposity index (BAI) has been recently proposed as an alternative index to body mass index (BMI) and waist circumference (WC) to evaluate adiposity in adults, with special focus on its ability to discriminate gender specificities on adiposity. Endothelial dysfunction, circulating endothelial cells (CECs), endothelin-1 and adipocytokines are all related to atherosclerosis and nowadays considered as markers of emerging cardiovascular (CV) risk. This study aimed to determine in normal weight and obese adolescents which measures of body composition (BAI and z-BMI) or distribution (WC) correlate better with emerging CV risk markers.

PATIENTS

Forty adolescents were selected according to BMI: normal weight (n = 20; 7 girls/13 boys, 14·7 ± 1·4 years, 53·4 ± 6·0 kg, z-BMI 0·6 ± 0·1) and obese ones (n = 20; 13 girls/7 boys, 14·1± 1·0 years, 86·7 ± 11·5 kg, z-BMI 2·7 ± 0·4).

MEASUREMENTS

Body fat and fat mass were measured by dual-energy X-ray absorptiometry (DXA). Non-nutritive skin microvascular reactivity was evaluated by laser Doppler flowmetry with iontophoretic release of vasoactive drugs. Activated CECs were assessed by flow cytometric analysis.

RESULTS

In adolescents, the measurement of % fat by DXA showed high correlation with BAI (ρ = 0·75, P < 0·0001), z-BMI (r = 0·84, P < 0·0001) and WC (r = 0·83, P < 0·0001). Endothelin-1 and activated CECs did not correlate with any anthropometric measures while adipocytokines expressed variable associations among them. Endothelium-dependent vasodilation showed higher correlation with BAI (r = -0·51, P < 0·0001) compared to z-BMI (r = -0·40, P < 0·001) or WC (r = -0·45, P < 0·001), specially on females.

CONCLUSIONS

BAI was associated with emerging CV risk markers in adolescents but further research is needed to evaluate its potential in clinical and epidemiological sets.

Childhood obesity and cardiovascular dysfunction

Obesity-related cardiovascular disease in children is becoming more prevalent in conjunction with the rise in childhood obesity. Children with obesity are predisposed to an increased risk of cardiovascular morbidity and mortality in adulthood. Importantly, research in children with obesity over the last decade has demonstrated that children may exhibit early signs of cardiovascular dysfunction as a result of their excess adiposity, often independent of other obesity-related comorbidities such as dyslipidemia and insulin resistance. The clinical evidence is accumulating to suggest that the cardiovascular damage, once observed only in adults, is also occurring in obese children. The objective of this review is to provide a synopsis of the current research on cardiovascular abnormalities in children with obesity and highlight the importance and need for early detection and prevention programs to mitigate this potentially serious health problem.

Body Fat Is Associated With Reduced Aortic Stiffness Until Middle Age

Obesity is a major risk factor for cardiometabolic disease, but the effect of body composition on vascular aging and arterial stiffness remains uncertain. We investigated relationships among body composition, blood pressure, age, and aortic pulse wave velocity in healthy individuals. Pulse wave velocity in the thoracic aorta, an indicator of central arterial stiffness, was measured in 221 volunteers (range, 18–72 years; mean, 40.3±13 years) who had no history of cardiovascular disease using cardiovascular MRI. In univariate analyses, age ( r =0.78; P <0.001) and blood pressure ( r =0.41; P <0.001) showed a strong positive association with pulse wave velocity. In multivariate analysis, after adjustment for age, sex, and mean arterial blood pressure, elevated body fat% was associated with reduced aortic stiffness until the age of 50 years, thereafter adiposity had an increasingly positive association with aortic stiffness (β=0.16; P <0.001). Body fat% was positively associated with cardiac output when age, sex, height, and absolute lean mass were adjusted for (β=0.23; P =0.002). These findings suggest that the cardiovascular system of young adults may be capable of adapting to the state of obesity and that an adverse association between body fat and aortic stiffness is only apparent in later life.

Arterial compliance is increased in children with type 2 diabetes compared with normal weight peers but not obese peers

BACKGROUND

We reported that obesity was associated with increased arterial compliance in children, possibly due to accelerated vascular maturation. Here, we explored the additional burden of type 2 diabetes (T2DM) on vascular function in children.

METHODS

Fifty normal weight [body mass index (BMI) 25-75%], 58 obese (BMI ≥ 95%), and 34 children with T2DM diagnosed by American Diabetes Association (ADA) criteria ages 10-18 yr were studied. Large and small artery elasticity (LAEI and SAEI, respectively) were measured by diastolic pulse-wave contour analysis.

RESULTS

SAEI was 27% higher in children with T2DM compared to normal weight children (p = 0.005). Mean LAEI for those with T2DM not different from either group. In the group with T2DM, both SAEI and LAEI increased with age up to 16 yr, but declined thereafter. The strongest multivariable model predicting SAEI in children with T2DM combined lean mass, systolic blood pressure (SBP), and glucose (r2  = 0.59); for predicting LAEI, the strongest model included height, SBP, and low-density lipid-cholesterol (r2  = 0.61).

CONCLUSION

The lower arterial compliance in older adolescents with T2DM compared to that of their peers without diabetes may indicate a premature maturation of the vascular system; however, follow-up will clarify whether these vascular changes portend an early increase in diabetes-associated cardiovascular disease risk.

Metabolic syndrome and arterial elasticity in youth

OBJECTIVE

To compare arterial elasticity in children, adolescents, and young adults with and without metabolic syndrome (MetS), and to assess which MetS components, demographic measures, and body composition measures are associated with arterial elasticity.

MATERIALS/METHODS

Two-hundred six subjects (107 females and 99 males) between the ages of 10 and 20years were recruited by local newspaper advertisements, university email advertisements, and informational flyers. Subjects were assessed on MetS components, demographic measures, body composition measures, and arterial elasticity via radial tonometry. Forty-five subjects (22%) had MetS, as defined by the International Diabetes Federation, and 161 subjects (78%) did not.

RESULTS

The primary novel finding was that group differences were not observed for large artery elasticity index (LAEI) (MetS=16.1±4.4 (ml×mmHg(-1))×10 (mean±SD), control=15.4±4.9, (ml×mmHg(-1))×10, p=0.349), and small artery elasticity index (SAEI) (MetS=9.2±2.7 (ml×mmHg(-1))×100, control=8.4±2.9, (ml×mmHg(-1))×100, p=0.063). In the MetS group, fat free mass was positively associated with arterial elasticity, and was the strongest multivariate predictor of LAEI (partial R(2)=0.41) and SAEI (partial R(2)=0.29).

CONCLUSIONS

Youth with MetS did not exhibit differences in LAEI and SAEI compared to controls. Furthermore, fat free mass of youth with MetS was positively associated with arterial elasticity, and was the strongest predictor of both LAEI and SAEI. The clinical implication is that exercise intervention designed to increase fat free mass might increase arterial elasticity in youth, particularly in youth with MetS.

Metabolic syndrome and daily ambulation in children, adolescents, and young adults

PURPOSES

To compare daily ambulatory measures in children, adolescents, and young adults with and without metabolic syndrome and to assess which metabolic syndrome components, demographic measures, and body composition measures are associated with daily ambulatory measures.

METHODS

Two-hundred fifty subjects between the ages of 10 and 30 yr were assessed on metabolic syndrome components, demographic and clinical measures, body fat percentage, and daily ambulatory strides, durations, and cadences during seven consecutive days. Of the 250 subjects, 45 had metabolic syndrome, as defined by the International Diabetes Federation.

RESULTS

Subjects with metabolic syndrome ambulated at a slower daily average cadence than those without metabolic syndrome (13.6 ± 2.2 vs 14.9 ± 3.2 strides per minute; P = 0.012), and they had slower cadences for continuous durations of 60 min (P = 0.006), 30 min (P = 0.005), 20 min (P = 0.003), 5 min (P = 0.002), and 1 min (P = 0.001). However, the total amount of time spent ambulating each day was not different (P = 0.077). After adjustment for metabolic syndrome status, average cadence is linearly associated with body fat percentage (P < 0.001) and fat mass (P < 0.01). Group difference in average cadence was no longer significant after adjusting for body fat percentage (P = 0.683) and fat mass (P = 0.973).

CONCLUSIONS

Children, adolescents, and young adults with metabolic syndrome ambulate more slowly and take fewer strides throughout the day than those without metabolic syndrome, although the total amount of time spent ambulating is not different. Furthermore, the detrimental influence of metabolic syndrome on ambulatory cadence is primarily a function of body fatness.

Blood Pressure and Obesity Exert Independent Influences on Pulse Wave Velocity in Youth

The objective was to analyze pulse wave velocity (PWV) in normotensive, high-normal, and hypertensive youths by using aortic-derived parameters from peripheral recordings. The impact of obesity on vascular phenotypes was also analyzed. A total of 501 whites from 8 to 18 years of age were included. The subjects were divided according to BP criteria: 424 (85%) were normotensive, 56 (11%) high-normal, and 21 (4%) hypertensive. Obesity was present in 284 (56%) and overweight in 138 (28%). Pulse wave analysis using a SphygmoCor device was performed to determine central blood pressure (BP), augmentation index, and measurement of PWV. Among the BP groups, differences appeared in age, sex, and height but not in body mass index. Significant differences in peripheral and central systolic and diastolic BPs and pulse pressures were observed within groups. A graded increase in PWV was present across the BP strata without differences in augmentation index. Using a multiple regression analysis, age, BP groups, and obesity status were independently associated with PWV. Older and hypertensive subjects had the highest PWV, whereas, from normal weight status to obesity, PWV decreased. Likewise, PWV was positively related to peripheral or central systolic BP and negatively related to body mass index z score. For 1 SD of peripheral systolic BP, PWV increased 0.329 m/s, and for 1 SD of body mass index z score PWV decreased 0.129 m/s. In conclusion, PWV is increased in hypertensive and even in high-normal children and adolescents. Furthermore, obesity, the factor most frequently related to essential hypertension in adolescents, blunted the expected increment in PWV of hypertensive and high-normal subjects.

Sex differences in vascular compliance in normal-weight but not obese boys and girls: the effect of body composition

Objectives. To determine the effect of sex and obesity on vascular function in children and explore potential mechanisms that account for differences in vascular function. Methods. Participants were 61 (30 boys) normal-weight (BMI 25-75% ile for age and sex) and 62 (30 boys) obese (BMI ≥ 95% ile) children of ages 8-18 years. Measurements of large and small artery elastic index (LAEI and SAEI, resp.) and reactive hyperemia index (RHI) were obtained at rest, along with anthropometric and biochemical information. Results. In normal-weight children, LAEI was 16% higher in males than females (P = 0.04) with a similar trend for SAEI (13% higher in males, P = 0.067). In obese children, no sex-related differences in vascular measures were observed. In multivariable models, sex differences in arterial compliance were explained by higher lean mass in normal-weight boys. Fat mass predicted LAEI and SAEI in both normal-weight and obese females, but fat mass predicted arterial compliance in boys when fat mass exceeded 24 kg (37% of the sample). Conclusions. Normal-weight males have higher arterial compliance than normal-weight females due to increased lean mass, but sex-related differences were not observed among obese children due to a lack of sex-related differences in lean or fat mass.