Search

Background: Endothelial dysfunction measured via flow-mediated dilation (FMD) is associated with greater risk of future hypertension and cardiovascular events in postmenopausal women. Aerobic exercise training has been shown to improve endothelial function in Caucasian populations, but has not been evaluated specifically in African Americans. This has clinical importance due to the increased prevalence of cardiovascular disease in African Americans. Methods: In the present pilot study, 8 African American (age: 55.8±1.7 years, peak oxygen uptake [VO2 peak]: 21.0±3.9 mL/kg/minute, body mass index [BMI]: 30.1± 6.3 kg/m2) and 16 Caucasian (age: 57.2±5.9 years, VO2 peak: 21.8±3.7 mL/kg/minute, BMI: 29.3±5.2 kg/m2) sedentary postmenopausal women underwent brachial artery FMD measurements before and after 12 weeks of aerobic exercise training. FMD was quantified by comparing B-mode ultrasound images of the brachial artery at rest and following reactive hyperemia after 5 minutes of forearm occlusion. Participants performed aerobic exercise training 4 days per week for 12 weeks. Results: Despite improvements in fitness in both groups, aerobic exercise training did not significantly improve FMD in African American (5.8% to 5.7%, p=0.950) or Caucasian postmenopausal women (5.7% to 6.6%, p=0.267). In women with the greatest impairment in endothelial function at baseline (FMD<4.5%), a significant improvement in FMD was observed, independent of race, following exercise training (2.2% to 6.2%, p=0.007). Conclusion: The benefits of aerobic exercise training on endothelial function in postmenopausal women are most pronounced in women with endothelial dysfunction prior to training and do not appear to be affected by race. [ABSTRACT FROM AUTHOR]

Introduction: Increasing arterial stiffness is a feature of vascular aging that is accelerated by conditions that enhance cardiovascular risk, including diabetes mellitus. Multiple studies demonstrate divergence of carotid-femoral pulse wave velocity and augmentation index in persons with diabetes mellitus, though mechanisms responsible for this are unclear., Materials and Methods: We tested the effect of acutely and independently increasing plasma glucose, plasma insulin, or both on hemodynamic function and markers of arterial stiffness (including carotid-femoral pulse wave velocity, augmentation index, forward and backward wave reflection amplitude, and wave reflection magnitude) in a four-arm, randomized study of healthy young adults., Results: Carotid-femoral pulse wave velocity increased only during hyperglycemic-hyperinsulinemia (+0.36 m/s; p  = 0.032), while other markers of arterial stiffness did not change (all p  > 0.05). Heart rate (+3.62 bpm; p  = 0.009), mean arterial pressure (+4.14 mmHg; p  = 0.033), central diastolic blood pressure (+4.16 mmHg; p  = 0.038), and peripheral diastolic blood pressure (+4.09 mmHg; p  = 0.044) also significantly increased during hyperglycemic-hyperinsulinemia., Conclusions: Hyperglycemic-hyperinsulinemia acutely increased cfPWV, heart rate, mean arterial pressure, and diastolic blood pressure in healthy humans, perhaps reflecting enhanced sympathetic tone. Whether repeated bouts of hyperglycemia with hyperinsulinemia contribute to chronically-enhanced arterial stiffness remains unknown.

Purpose: To examine the utility of the Borg (6-20) and adult OMNI walk/run (0-10) ratings of perceived exertion (RPE) scales as markers of the blood lactate response to exercise., Methods: Thirty-six (26 females and 10 males) individuals with the metabolic syndrome (mean+/-SEM: age, 45.8+/-2.0 yr; height, 168.4+/-1.3 cm; weight, 100.4+/-3.6 kg) completed a continuous peak oxygen uptake (VO2peak)/lactate threshold (LT) treadmill protocol. VO2 (mL.kg.min), blood lactate concentration (BLC, mM), and heart rate (bpm) were measured at the end of each stage. RPE were assessed at 2:15 and 2:45 of each 3-min stage using both RPE scales presented in a counterbalanced order. Participants were read standardized instructions specific to each scale. The LT and BLC of 2.5 and 4.0 mM were determined from the blood lactate-velocity relationship., Results: The mean Borg, OMNI, and standardized (to the Borg scale) OMNI-RPE values at the LT and BLC of 2.5 mM, 4.0 mM, and peak ranged from 10.1 to 16.9, 3.1 to 8.2, and 9.9 to 17.1, respectively. No differences were observed between Borg and standardized OMNI-RPE at any exercise intensity. The correlation within and between Borg- and OMNI-RPE and the velocities associated with LT, BLC of 2.5 mM, 4.0 mM, and peak ranged from r=0.82 to 0.93 (P<0.01). Mean differences (95% CI) between the Borg- and standardized OMNI-RPE at LT, and BLC of 2.5 mM, 4.0 mM, and peak were 0.27 (-2.26, 2.80), -0.48 (-3.14, 2.18), -0.29 (-2.92, 2.35), and 0.10 (-1.65, 1.84), respectively., Conclusion: Both the Borg and OMNI walk/run scales demonstrate predictive utility as markers of the blood lactate response to incremental exercise in individuals with the metabolic syndrome.