Resistance and aerobic exercise is recommended for cardiovascular health and disease prevention. However, the accompanying increase in arterial pressure during resistance exercise may be detrimental to vascular health. This study tests the vascular benefits of aerobic compared with resistance exercise on preventing impaired vascular function induced by a single weight lifting session that is associated with acute hypertension. Healthy, lean sedentary (SED) subjects, weight lifters, runners (>15 miles/wk), and cross trainers (chronic aerobic and resistance exercisers), underwent a single progressive leg press weight lifting session with blood pressure measurements. Brachial artery flow-mediated vasodilation (FMD; an index of arterial endothelial function) was determined using ultrasonography immediately before and after weight lifting. Sublingual nitroglycerin (0.4 mg) was used to determine endothelium-independent dilation after weight lifting. All subjects were normotensive with similar blood pressure responses during exercise. Baseline FMD was lower in runners (5.4 ± 0.5%; n = 13) and cross trainers (4.44 ± 0.3%; n = 13) vs. SED (8.5 ± 0.8%; n = 13; P = 0.037). Brachial FMD improved in conditioned weight lifters (to 8.8 ± 0.9%; P = 0.007) and runners (to 7.6 ± 0.6%; P < 0.001) but not cross trainers (to 5.3 ± 0.6%; P = NS) after acute hypertension. FMD was decreased in SED (to 5.7 ± 0.4%; P = 0.019). Dilation to nitroglycerin was similar among groups. These data suggest that endothelial responses are maintained after exposure to a single bout of weight lifting in resistance and aerobic athletes. Resistance and aerobic exercise may confer similar protection against acute vascular insults such as exertional hypertension.

Brachial artery flow mediated vasodilation in exercise trained (ET) individuals is maintained after a single bout of heavy resistance exercise compared to sedentary (SED) individuals. The purpose of this study was to determine if vasodilation is also maintained in the microcirculation of ET individuals. A total of 51 SED and ET individuals underwent gluteal subcutaneous fat biopsy before and after performing a single bout of leg press exercise. Adipose arterioles were cannulated in an organ bath and vasodilation to acetylcholine was assessed ± the endothelial nitric oxide inhibitor L-NAME, the cyclooxygenase inhibitor indomethacin, or the hydrogen peroxide scavenger PEG-catalase. Separate vessels (isolated from the same groups) were exposed to an intraluminal pressure of 150 mmHg for 30 minutes to mimic the pressor response which occurs with isometric exercise. Vasodilation to acetylcholine was reduced in microvessels from SED subjects after either a single weight lifting session or exposure to increased intraluminal pressure whereas microvessels from ET individuals maintained acetylcholine-mediated vasodilation. Prior to weight lifting, vasodilation of microvessels from ET individuals was reduced in the presence of L-NAME and indomethacin. After weight lifting or exposure to increased intraluminal pressure, PEG-catalase significantly reduced vasodilation while L-NAME and indomethacin had no effect. These results indicate that 1) endothelium-dependent vasodilation in the microvasculature is maintained following heavy resistance exercise in ET individuals but not in SED subjects, and that 2) high pressure alone or during weight lifting may induce a mechanistic switch in the microvasculature to favor hydrogen peroxide as the vasoactive mediator of dilation.

OBJECTIVEWe evaluated the prevalence of endothelial dysfunction as measured by flow-mediated dilatation (FMD) of the brachial artery and carotid intima-media thickness (c-IMT) in relationship to vascular inflammatory biomarkers in preadolescent children with type 1 diabetes.RESEARCH DESIGN AND METHODSWe studied 21 type 1 diabetic children (aged 8.3 ± 0.3 years with diabetes duration of 4.3 ± 0.4 years) and 15 group-matched healthy siblings (aged 7.6 ± 0.3 years). Fasting plasma glucose (FPG), lipid profile, HbA1c, high-sensitivity C-reactive protein (hs-CRP), fibrinogen, homocysteine, and erythrocyte (red blood cell [RBC]) folate were evaluated in all subjects. Each subject underwent c-IMT and brachial artery FMD percentage (FMD%) measurements using high-resolution vascular ultrasound.RESULTSType 1 diabetic children had higher FPG (173.4 ± 7.9 mg/dL vs. 81.40 ± 1.7 mg/dL; P < 0.0001), HbA1c (8.0 ± 0.2% vs. 5.0 ± 0.1%; P < 0.0001), and hs-CRP (1.8 ± 0.3 vs. 0.70 ± 0.2; P = 0.017) than control children without significant differences in BMI, homocysteine, and fibrinogen levels; RBC folate content; and c-IMT between the groups. Children with type 1 diabetes had lower FMD% than control children (7.1 ± 0.8% vs. 9.8 ± 1.1%; P = 0.04), whereas c-IMT did not differ between groups.CONCLUSIONSPreadolescent children with type 1 diabetes and mean diabetes duration of 4 years displayed evidence of low-intensity vascular inflammation and attenuated FMD measurements. These data suggest that endothelial dysfunction and systemic inflammation, known harbingers of future cardiovascular risk, are present even in preadolescent children.

Recommendations for the measurement of brachial flow-mediated dilation (FMD) typically suggest images be obtained at identical times in the cardiac cycle, usually end diastole (QRS complex onset). This recommendation presumes that inter-individual differences in arterial compliance are minimized. However, published evidence is conflicting. Furthermore, ECG gating is not available on many ultrasound systems; it requires an expensive software upgrade or increased image processing time. We tested whether analysis of images acquired with QRS gating or with the more simplified method of image averaging would yield similar results. We analyzed FMD and nitroglycerinmediated dilation (NMD) in 29 adults with type 2 diabetes mellitus and in 31 older adults and 12 young adults without diabetes, yielding a range of brachial artery distensibility. FMD and NMD were measured using recommended QRS-gated brachial artery diameter measurements and, alternatively, the average brachial diameters over the entire R-R interval. We found strong agreement between both methods for FMD and NMD (intraclass correlation coefficients ϭ 0.88 -0.99). Measuring FMD and NMD using average diameter measurements significantly reduced post-image-processing time (658.9 Ϯ 71.6 vs. 1,024.1 Ϯ 167.6 s for QRS-gated analysis, P Ͻ 0.001). FMD and NMD measurements based on average diameter measurements can be performed without reducing accuracy. This finding may allow for simplification of FMD measurement and aid in the development of FMD as a potentially useful clinical tool. endothelium; shear stress; flow-mediated dilation; method ENDOTHELIAL DYSFUNCTION is characterized by a proinflammatory, prothrombotic, and vasoconstrictive phenotype (16). Maintenance of nitric oxide (NO) bioavailability through activation of endothelial NO synthase is of central importance in maintaining vascular homeostasis.Substantial evidence supports the concept that detection of endothelial dysfunction in the brachial artery is an indicator of systemic endothelial dysfunction (32). Brachial artery reactivity [flow-mediated dilation (FMD)], as measured by highresolution vascular ultrasound prior to and following a hyperemic flow stimulus, is highly dependent on NO bioavailability (9,20). Furthermore, endothelial dysfunction as detected by FMD predicts future cardiovascular risk in those with and without diagnosed coronary artery disease (4,5,11,15,25,26,28,30,35). FMD's ability to stratify individuals into low-, intermediate-, and high-risk categories for future cardiovascular events (35, 36) not only yields potentially clinically relevant information but also identifies the efficacy of medical interventions that enhance endothelial function (23,25).The potential of brachial FMD to be used as a barometer of cardiovascular risk at a population level has led to efforts to standardize the technique with the hope of maximizing the validity and reproducibility of the measurement (7). Recent reviews suggest further refinements to these recommendations (8,18,29). These publications recom...