simple anthropometric measures of body composition and fat distribution are widely accepted as being the most practical and valuable approach to diagnose excess body fat , usually classified as overweight and obesity . excess body fat can have an adverse effect on health , leading to development of various chronic diseases , cardiovascular ( cv ) disease being the most typical [ 14 ] . the oldest and the most commonly used anthropometric measure for this purpose is the body mass index ( bmi ) , an estimate of body fat calculated from height and weight . it distinguishes 3 categories  normal weight ( < 24.9 kg / m ) , overweight ( 2529.9 kg / m ) and obese ( 30 kg / m )  without precise distinction between body fat and other tissues , such as musculoskeletal . also , bmi is insensitive to the relative distribution of body fat . the assessment of body fat percentage ( % bf ) is another measure often used , but has similar limitation as bmi . because health risk seems to be primarily associated with abdominal fat [ 68 ] , measures for assessment of excess abdominal fat , such as waist circumference ( wc ) , waist - hip ratio ( whpr ) and waist - height ratio ( whtr ) were introduced as more specific alternatives . all these measures were shown to be associated with metabolic disorders and cv risk factors in different patterns and extent [ 914 ] . some of these measures were also reported to be related to arterial stiffness , an important , independent and proven cv risk factor [ 1517 ] . several studies showed association of the anthropometric measures with arterial stiffness in obese population , with clear sex differences . however , little is known about these associations in healthy and generally non - obese populations . only a few studies have examined the association of several anthropometric measures with arterial stiffness in healthy populations close to normal weight , but their results were inconsistent [ 2022 ] . for instance , in the study examining relation of bmi and bf content with stiffness index , augmentation index ( aix ) and pulse pressure ( pp ) , wykretowicz et al . , showed that bmi was not a good predictor of arterial stiffness . on the contrary , wildman et al .   found bmi together with wc and whpr was strongly associated with pulse wave velocity ( pwv ) , the direct marker of arterial stiffness . further , maher et al .   showed that none of the anthropometric measures was associated with aix . arterial stiffness can be assessed by several approaches . a direct arterial stiffness index , pwv , considered as a  gold standard method , aix is an indirect marker of arterial stiffness and a direct measure of wave reflection , also confirmed to be associated with cv risk . central systolic blood pressure ( csbp ) , an indicator of central hemodynamics , is a complementary stiffness index , also used as a predictor of cv events . the aim of our study was assessment of sex - specific association of different anthropometric measures of body composition ( bmi,%bf , wc , whtr and whpr ) with a spectrum of arterial stiffness indices ( pwv , aix and csbp ) in healthy and generally non - obese subjects . in order to clearly distinguish the effect of each anthropometric measure , the data were complemented with a wide set of known confounders involved in the complex pathophysiology of the increased arterial stiffness , such as age , heart rate , blood pressures , blood lipids and smoking . the study was conducted at the university of split school of medicine , as a part of larger genetic epidemiology research program [ 2729 ] during 20092010 . participants were unselected , healthy adults , > 18 years of age , originating from the city of split ( croatia ) and surrounding areas . after providing a signed informed consent for participation in the study , subjects with history of cardiovascular diseases ( hypertension , coronary artery disease , myocardial infarction , heart failure or arrhythmia ) , cerebrovascular diseases , cancer , thyroid disturbances , diabetes mellitus , elevated serum glucose , triglycerides and cholesterol were excluded from the study . also , those taking lipid - lowering , blood sugar - lowering , antihypertensive or other cardiovascular medications were excluded from the study . blood sampling and anthropometric and arterial stiffness measurements were performed in the morning , after overnight fasting . blood glucose , triglycerides , and total ldl and hdl cholesterol were measured by standard laboratory procedures . smoking status was obtained from a questionnaire and was coded into categories : current smokers , former smokers and non - smokers . height and weight were measured using a digital scale ( seca 789 bionetics , canada ) with the precision of 0.1 cm and 0.1 kg , respectively . bmi was calculated by dividing the participant s weight ( kg ) by square of height ( m ) . wc was measured using a tape measurer placed halfway between the lower border of the ribs and the iliac crest in a horizontal plane , and was measured to the nearest 0.1 cm . percent bf was determined from measurements of skinfold thickness taken at 4 standard sites  biceps , triceps , subscapular and suprailiac  using harpenden skinfold caliper ( cms instruments , london , uk ) body density was calculated from the sum of the 4 skinfold measurements according to durnin and womersley , and final percentage of body fat was calculated by siri s equation . all hemodynamic measurements were preformed in a temperature - controlled room , unaffected by external environmental influences , in a supine position after resting for 15 min . arterial stiffness was measured non - invasively using arteriograph ( tensiomed ltd . , budapest , hungary ) , a recently introduced and validated device for arterial stiffness assessment [ 3436 ] . arteriograph uses an oscillometric principle for measurement of the aortic pwv and pulse wave analysis . essentially , the device measures periodic pressure changes in the inflated cuff ( 35 mmhg above systolic pressure ) induced by fluctuations in pulsatile pressure in the brachial artery beneath . the cuff was applied to the upper right arm . simultaneously with the parameters of arterial stiffness ( pwv ( m / s ) , caix ( % ) , csbp ( mmhg ) ) , the device also recorded systolic and diastolic blood pressures ( sbp and dbp , mmhg ) and heart rate ( min ) . mean arterial pressure ( map ) was subsequently calculated by formula : map = dbp+(sbp - dbp)/3 . all measurements were performed by 2 well - trained investigators ( db and gg ) . the average values of 2 measurements that satisfied quality control , taken 5 minutes apart , were used . the pearson correlations and multiple regression analysis ( mlr ) were used to assess the associations of each anthropometric measure of body composition with a particular arterial stiffness index within each sex group of subjects . potential confounding effects adjusted for were age , heart rate , height , sbp , dbp , smoking , total ldl and hdl cholesterol and triglycerides . in order to avoid biased results , outliers were identified and removed from the initial dataset ( n=352 ) . in total , 7 univariate ( z>3.3 ) and 2 overlapping extreme multivariate outliers ( mahalanobis d2 , p0.001 ) were removed ( n=7 ) . since no a priori hypothesis was made to determine the order of entry of the potential predictor factors ( see above ) , a direct method for the regression analyses was used . the entering of the predictor variable was followed by removing the one with the lowest non - significant regression coefficient and by subsequent regression analysis . the procedure was repeated until all non - significant predictors were removed or until further exclusions caused a deterioration of the model according to f - test . in each case , the direct regression model was followed by backward method to check for inconsistencies . finally , the optimal model of arterial stiffness index prediction with a particular anthropometric measure as independent variable was determined . normal distributions were evaluated with determination of skewness and histograms as well as with one - sample kolmogorov - smirnov test . independent sample t - tests as well as  tests were used for quantitative and qualitative variables , respectively , when evaluating the differences between sexes . all other statistical calculations were performed using spss software , version 13 ( spss inc . , the study was conducted at the university of split school of medicine , as a part of larger genetic epidemiology research program [ 2729 ] during 20092010 . participants were unselected , healthy adults , > 18 years of age , originating from the city of split ( croatia ) and surrounding areas . after providing a signed informed consent for participation in the study , subjects with history of cardiovascular diseases ( hypertension , coronary artery disease , myocardial infarction , heart failure or arrhythmia ) , cerebrovascular diseases , cancer , thyroid disturbances , diabetes mellitus , elevated serum glucose , triglycerides and cholesterol were excluded from the study . also , those taking lipid - lowering , blood sugar - lowering , antihypertensive or other cardiovascular medications were excluded from the study . blood sampling and anthropometric and arterial stiffness measurements were performed in the morning , after overnight fasting . blood glucose , triglycerides , and total ldl and hdl cholesterol were measured by standard laboratory procedures . smoking status was obtained from a questionnaire and was coded into categories : current smokers , former smokers and non - smokers . height and weight were measured using a digital scale ( seca 789 bionetics , canada ) with the precision of 0.1 cm and 0.1 kg , respectively . bmi was calculated by dividing the participant s weight ( kg ) by square of height ( m ) . wc was measured using a tape measurer placed halfway between the lower border of the ribs and the iliac crest in a horizontal plane , and was measured to the nearest 0.1 cm . biceps , triceps , subscapular and suprailiac  using harpenden skinfold caliper ( cms instruments , london , uk ) . body density was calculated from the sum of the 4 skinfold measurements according to durnin and womersley , and final percentage of body fat was calculated by siri s equation . all hemodynamic measurements were preformed in a temperature - controlled room , unaffected by external environmental influences , in a supine position after resting for 15 min . arterial stiffness was measured non - invasively using arteriograph ( tensiomed ltd . , budapest , hungary ) , a recently introduced and validated device for arterial stiffness assessment [ 3436 ] . arteriograph uses an oscillometric principle for measurement of the aortic pwv and pulse wave analysis . essentially , the device measures periodic pressure changes in the inflated cuff ( 35 mmhg above systolic pressure ) induced by fluctuations in pulsatile pressure in the brachial artery beneath . the cuff was applied to the upper right arm . simultaneously with the parameters of arterial stiffness ( pwv ( m / s ) , caix ( % ) , csbp ( mmhg ) ) , the device also recorded systolic and diastolic blood pressures ( sbp and dbp , mmhg ) and heart rate ( min ) . mean arterial pressure ( map ) was subsequently calculated by formula : map = dbp+(sbp - dbp)/3 . all measurements were performed by 2 well - trained investigators ( db and gg ) . the average values of 2 measurements that satisfied quality control , taken 5 minutes apart , were used . the pearson correlations and multiple regression analysis ( mlr ) were used to assess the associations of each anthropometric measure of body composition with a particular arterial stiffness index within each sex group of subjects . potential confounding effects adjusted for were age , heart rate , height , sbp , dbp , smoking , total ldl and hdl cholesterol and triglycerides . in order to avoid biased results , outliers were identified and removed from the initial dataset ( n=352 ) . in total , 7 univariate ( z>3.3 ) and 2 overlapping extreme multivariate outliers ( mahalanobis d2 , p0.001 ) were removed ( n=7 ) . since no a priori hypothesis was made to determine the order of entry of the potential predictor factors ( see above ) , a direct method for the regression analyses was used . the entering of the predictor variable was followed by removing the one with the lowest non - significant regression coefficient and by subsequent regression analysis . the procedure was repeated until all non - significant predictors were removed or until further exclusions caused a deterioration of the model according to f - test . in each case , the direct regression model was followed by backward method to check for inconsistencies . finally , the optimal model of arterial stiffness index prediction with a particular anthropometric measure as independent variable was determined . normal distributions were evaluated with determination of skewness and histograms as well as with one - sample kolmogorov - smirnov test . independent sample t - tests as well as  tests were used for quantitative and qualitative variables , respectively , when evaluating the differences between sexes . all other statistical calculations were performed using spss software , version 13 ( spss inc . , there were 152 ( 43.2% ) men and 200 ( 56.8% ) premenopausal women . in both sexes , body composition , hemodynamic and biochemical parameters were within the range expected for normally distributed population ( table 1 ) . women had significantly lower csbp and greater aix values , while there was no difference in pwv between sexes . our population sample was predominantly non - obese  according to bmi , 52% of subjects had normal body weight , 38% were overweight and 10% were obese . mean ( sd ) bmi was 23.953.60 in the female and 25.843.77 in the male subjects . the analysis revealed several differences between the females and the males . in the female group univariate analysis showed that most correlations between measures of body composition and arterial stiffness indices were positive and mainly significant ( table 2 , bold column ) . however , application of a mlr analysis revealed quite different results . in general , after adjustment for known risk factors , multivariate models detected 3 measures of body composition ( bmi , wc and whtr ) as weak and inverse predictors of pwv and aix ( table 2 ) . in the csbp models , as independent predictors , the 3 measures of body composition ( bmi , wc and whtr ) , explained only several percentages of arterial stiffness variance ( sr=0.0030.02 ) . other measures , such as % bf and whpr , were not significant predictors of arterial stiffness in the female group . in the male group , similar to the females , correlations between measures of body composition and arterial stiffness indices , determined by univariate analysis , were positive and mainly significant ( table 3 , bold column ) . again , after application of the mlr and adjustment for known confounders , most of these univariate associations disappeared ( table 3 ) . in contrast to females , bmi was the only common and inverse predictor of arterial stiffness indices , pwv and csbp . similar to the female group , measures of body composition as independent predictors explained only several percent of arterial stiffness variance ( sr=0.0050.02 ) . measures such as % bf and whpr were not significant predictors in the male group . finally , relative to the male models , female models in general explained 10% to 15% less variance , and differed in some predictors ( tables 2 and 3 ) . the results of this study show that in the sample of healthy and generally non - obese subjects the positive univariate associations of anthropometric measures of body composition with arterial stiffness indices were not consistent , as their significance and strength depended on sex but also on the measure of body composition and arterial stiffness index . in addition , mlr analysis revealed that these associations were strongly confounded by the arterial stiffness risk factors such as age , blood pressures , height , heart rate , blood lipids and/or smoking . after removal of their confounding effects , the body composition measures turned out to be weak and inverse predictors of arterial stiffness , and their influence was sex - dependent . namely , bmi , wc and whtr were key predictors of arterial stiffness in the females , while bmi was the principal predictor in the males . these key findings of our study seemingly contradict the results of several other studies that showed stronger and positive association of anthropometric measures with the arterial stiffness indices . in fact , our results indicate a possible explanation for discrepancies among these studies , as they did not completely distinguish the influence of other risk factors on arterial stiffness . namely , these studies used univariate correlations   or did not include all confounding factors within the best - fitted models of prediction , thus their data interpretation might be insufficient because confounding effects were not removed . actually , the initial steps in our analysis also showed similar results until we applied mlr . we therefore strongly suggest all further studies in this area to adopt a more critical approach when distinguishing body composition measures effects on arterial stiffness . generally , the inverse association of anthropometric measures and arterial stiffness might appear to be surprising , but similar results were obtained by several other authors as well . it was suggested that a decrease in peripheral resistance due to hyperinsulinemia   or low - grade inflammation , that is actually accompanied with excess body fat , could lead to decreased wave reflection and consequently decreased arterial stiffness values . this implies that the observed association was probably due to changes in peripheral resistance instead of direct changes in arterial stiffness . despite the bmi theoretical limitation ( it does not show relative fat distribution ) , it was the most strongly associated with arterial stiffness in both the female and male populations . it had similar predictive value in the females as 2 central anthropometric measures , wc and whtr , while it was the only measure predicting stiffness in the males . bmi has been in use for decades and its predictive value as a health risk factor has been well - investigated and confirmed . although it has been also increasingly criticized , our results indicate that it is still a valuable predictor . another parameter , wc , measures both abdominal subcutaneous and intra - abdominal amount of fat , and it has also been confirmed as a predictors of obesity - related health risk . the weakness of the measure is that it does not take into account a person s stature . two people with the same wc can have different amounts of fat depending on their height . we found that the  corrected  measure , whtr , was as good a parameter as wc in the females , indicating their equal usefulness in practice . this is in line with the study of nordstrand at al , who also showed whtr and wc to be predictors of arterial stiffness in obese females . lack of association of the skinfold assessed % bf with arterial stiffness could be explained by the fact that it depends on the amount of peripheral subcutaneous fat , regardless of the amount of visceral fat . difficulties in estimation of the fat amount and the use of standardized estimation formula , which were not validated in the investigated population , are likely reasons that % bf turned out to be an insignificant predictor . the possible reason why another measure , whpr , was not predicting arterial stiffness may be that hip circumference reflects different aspects of body composition , including muscle mass , fat mass and skeletal frame . thus , a reduction in weight usually results in a reduction of both waist and hip circumferences , and this will not necessarily result in changes in waist - hip ratio . in addition , several studies showed that hip circumference is even negatively associated with health risk . this may partially explain why whpr varies from weak to strong depending on population sample . wc and whtr were the only measures predicting arterial stiffness in the female , but not in the male group . this sex difference in association of anthropometric measures with arterial stiffness was also found by other authors , who showed that greater number of anthropometric measures were associated with arterial stiffness in women ( both non - obese and obese ) compared to men . in addition , our study also showed that different arterial stiffness indices were influenced by various confounding factors . underlining mechanisms explaining the described differences are yet to be examined . the limitations of this study include the cross - sectional nature of the study design , without a possibility for longitudinal follow - up . further , the estimates of percentage of body fat mass could have been a possible source of bias , since they were based on the anthropometric measurements of skinfold thickness and not other methods such as bioelectrical impedance or dual energy x - ray absorptiometry . the association of anthropometric measures of body composition and arterial stiffness in healthy , generally non - obese subjects suggests that bmi , wc and whtr are predictors of arterial stiffness in the females and bmi in the males . the associations of anthropometric measures with arterial stiffness confounded by different factors ( age , blood pressures , height , heart rate , blood lipids , smoking ) indicate the necessity for thorough regression analysis in similar studies .