Arterial stiffness, central blood pressure and body size in health and disease.

BACKGROUND: Body size is associated with increased brachial systolic blood pressure (SBP) and aortic stiffness. The aims of this study were to determine the relationships between central SBP and body size (determined by body mass index (BMI), waist circumference and waist/hip ratio) in health and disease. We also sought to determine if aortic stiffness was correlated with body size, independent of BP. METHODS: BMI, brachial BP and estimated central SBP (by SphygmoCor and radial P2) were recorded in controls (n=228), patients with diabetes (n=211), coronary artery disease (n=184) and end-stage kidney disease (n=68). Additional measures of waist circumference and arterial stiffness (aortic and brachial pulse wave velocity (PWV)) were recorded in a subgroup of 75 controls (aged 51 ± 12 years) who were carefully screened for factors affecting vascular function. RESULTS: BMI was associated with brachial (r=0.30; P<0.001) and central SBP (r=0.29; P<0.001) in the 228 controls, but not the patient populations (r<0.13; P>0.15 for all comparisons). In the control subgroup, waist circumference was also significantly correlated with brachial SBP (r=0.29; P=0.01), but not central SBP (r=0.22; P=0.07). Independent predictors of aortic PWV in the control subgroup were brachial SBP (ß=0.43; P<0.001), age (ß=0.37; P<0.001), waist circumference (ß=0.39; P=0.02) and female sex (ß=-0.24; P=0.03), but not BMI. CONCLUSION: In health, there are parallel increases in central and brachial SBP as BMI increases, but these relationships are not observed in the presence of chronic disease. Moreover, BP is a stronger correlate of arterial stiffness than body size.

Improvement of left ventricular function by lifestyle intervention in obesity: contributions of weight loss and reduced insulin resistance.

AIMS/HYPOTHESIS: Weight excess and insulin resistance mediate the link between obesity and left ventricular dysfunction. We investigated the effect and mechanisms of lifestyle modification on left ventricular function changes in obese patients. METHODS: Reduction of body weight and insulin resistance was sought using a behavioural intervention programme including dietary restrictions and exercise training in 261 patients (age 45 +/- 13 years) with BMI >or=30 kg/m(2), no history of cardiac disease and a normal stress echocardiogram. Each patient underwent echocardiographic measurement of myocardial deformation and velocity at baseline and at 6 month follow-up. RESULTS: Improvements in left ventricular systolic and diastolic function were demonstrated only in patients with significant reduction of weight and/or insulin resistance. Left ventricular improvement was less frequent in patients with diabetes than in those without (52% vs 82% for strain, 50% vs 81% for strain rate and 59% vs 80% for peak early diastolic myocardial velocity). The independent predictors of improved left ventricular systolic function (increase in strain) were: weight reduction (beta = 0.14, p < 0.05), decrease in the HOMA insulin resistance index (beta = 0.20, p < 0.005) and absence of diabetes (beta = 0.18, p < 0.02). A decrease in HbA(1c) also predicted improvement of left ventricular diastolic function (beta = 0.26, p < 0.001). There was a parallel increment in exercise capacity with intervention and increase in strain was independently correlated with increase in VO(2) (beta = 0.13, p < 0.04). CONCLUSIONS/INTERPRETATION: Effective lifestyle modifications in obese patients improve left ventricular systolic and diastolic function, but appear less effective with co-existing diabetes. The reversal of left ventricular function abnormalities is associated with reduction of both weight and insulin resistance, and is accompanied by an increase in cardiorespiratory fitness.

Variability in adherence to an unsupervised exercise prescription in obese women.

OBJECTIVE: To measure adherence to a specific exercise prescription (1500 kcal week(-1)) by objectively quantifying unsupervised exercise energy expenditure (ExEE) in obese women. DESIGN: The 16-week lifestyle intervention consisted of weekly meetings with research staff and promotion of increased ExEE (1500 kcal week(-1)) and a decreased dietary intake (-500 kcal day(-1)). PARTICIPANTS: Twenty-nine obese females (body mass index=36.8+/-5.0 kg m(-2), body fat=49.6+/-3.7%) from a hospital-based lifestyle intervention were included in the analysis. MEASUREMENTS: ExEE was estimated and monitored weekly using heart rate monitoring, and body composition was measured before and after the intervention by dual-energy X-ray absorptiometry. RESULTS: Free-living adherence to the exercise prescription was variable and, on average, modest such that 14% achieved 1500 kcal week(-1), and the average weekly ExEE (768 kcal week(-1)) represented 51.2% of the total amount prescribed. ExEE was correlated with changes in body weight (r=0.65, P<0.001) and fat mass (r=0.65, P<0.001). Achievement of a 5% weight loss target was dependent on the achievement of an ExEE level of 1000 kcal week(-1) (P<0.001). Exercise 'adherers' (>1000 kcal week(-1)) lost more weight (-9.9 vs -4.1 kg), more fat mass (-6.8 vs -3.0 kg) and more waist circumference (-9.8 vs -5.6 cm) when compared to 'non-adherers' (<1000 kcal week(-1)). DISCUSSION: Exercise is an integral component of lifestyle interventions aimed at reducing obesity and its complications. However, without accurate and objective measures of ExEE, it is difficult for relationships between exercise and health outcomes to be elucidated. The present study suggests an alternative to self-report to increase the confidence with which conclusions are drawn regarding the role of exercise within lifestyle interventions.

A randomised control trial comparing lifestyle groups, individual counselling and written information in the management of weight and health outcomes over 12 months.

OBJECTIVE: To investigate the effect of an 8-week group-based cognitive behaviour therapy lifestyle intervention with monthly follow-up to 6 months and further follow up at 12 months on change in weight and other weight-related variables, change in physical activity and change in health and well being compared to individualised dietetic treatment or giving an information booklet only (BO). DESIGN: A randomised controlled trial of two intervention groups, a group-based cognitive behaviour therapy lifestyle intervention, Fat Booters Incorporated--(FBI) and individualised dietetic treatment (IDT) and control group receiving an information booklet only (BO). The intervention groups involved weekly contact for 8 weeks with monthly follow-up to 6 months and further follow-up at 12 months, conducted in real practice setting. SUBJECTS: A total of 176 adults with body mass index (BMI)>27 kg/m2, mean (+/-s.d.) age 48+/-13 years, mean BMI 34+/-5.5 kg/m2. MAIN OUTCOME MEASURES: Weight, percent body fat, waist circumference, physical activity, health status, self-efficacy and satisfaction with life were measured at baseline, 3, 6 and 12 months. RESULTS: A statistically significant difference between groups was observed for weight change over time (P=0.05). The change in weight (mean+/-s.e.) for the FBI group was significantly greater than the BO group at 3 and 12 months (-2.8+/-0.7 compared to -1.0+/-0.6 kg, P<0.05 and -2.9+/-0.9 compared to +0.5+/-0.9 kg, P<0.005, respectively). Change in weight in the IDT group did not differ from the FBI group at any time point. For all groups, waist circumference was significantly less than baseline at all time points (P<0.001). Significant differences in self-efficacy were observed over time (P=0.02), with both intervention groups having greater self-efficacy than the BO group. Significant drop-outs occurred over time for all three groups. CONCLUSIONS: A cognitive behaviour-based lifestyle intervention was more effective than providing an information booklet alone and as effective as intensive individualised dietetic intervention in weight loss and improvements in self-efficacy.