Abstract 1536: Sex Specific Effects of Habitual Aerobic Exercise on Brachial Artery Flow-Mediated Dilation in Middle-Aged and Older Adults
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Background: Brachial artery endothelium-dependent dilation (flow-mediated dilation, FMD) is impaired with aging and is associated with increased risk for cardiovascular disease (CVD). Interventions that improve brachial artery FMD may help prevent age-related CVD. The purpose of this study was to determine if regular aerobic exercise increases brachial artery FMD in healthy middle-aged/older (ma/o) men and postmenopausal women. Methods: In a randomized controlled prospective study, non-obese (body mass index <30 kg/m2) ma/o previously sedentary adults (n=36, age 55–79 years) without CVD were studied before and after 8-weeks of vigorous daily walking (n=26, age 63±1 yrs) or non-exercise control (n=10, age 60±1 yrs). In a cross-sectional analysis, healthy ma/o sedentary (n=102, age 62±1 yrs) and endurance exercise-trained (n=65, age 62±1 yrs) men and postmenopausal women were studied. Results: Daily vigorous walking (~6 days/week, ~50 min/day, ~70% maximal heart rate) increased treadmill exercise time by ~2...Keywords:
Brachial artery
Aerobic Exercise
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The normal range of maximal values for oxygen consumption, heart rate, cardiac index, and stroke index during treadmill exercise testing are presented for 98 men and 104 women for ages 20-75 yr. These variables decrease with age in both sexes, but men show a significantly greater reduction than women with respect to oxygen consumption (P = 0.05), heart rate (P less than 0.02), and cardiac index (P less than 0.02). Comparison of the normal ranges of oxygen consumption, cardiac index, and stroke index indicated that men have significantly higher values than women (P less than 0.001). The normal range of heart rate was higher in younger men than women, but because of a more rapid decline with age in men, the older women had higher heart rates than the older men. Invasive measurements of cardiac index in 12 normal men and 11 normal women were within the defined normal range. These measurements showed that there was a greater increase in stroke index from supine rest to maximal upright exercise in men compared with the increase in women (means +/- SD, 12 +/- 9 m/m2 vs. 2 +/- 7 ml/m2, P less than 0.01).
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The purpose of this study was to determine whether increased intraluminal pressure is the damaging factor that reduces flow-mediated dilation (FMD) in young, healthy subjects after resistance exercise to maximal exertion.Attenuating the rise in brachial artery pressure during weight lifting by placing a blood pressure cuff on the upper arm prevents postexercise impairment of brachial artery FMD in sedentary individuals.Nine sedentary individuals who exercise once a week or less and six exercise-trained individuals who exercise three times a week or more performed leg press exercise to maximal exertion on two separate occasions. During one visit, a blood pressure cuff, proximal to the site of brachial artery measurement, was inflated to 100 mm Hg to protect the distal vasculature from the rise in intraluminal pressure, which occurs during resistance exercise. Brachial artery FMD was determined using ultrasonography before and 30 min after weight lifting.Without the protective cuff, brachial artery FMD in sedentary individuals was reduced after weight lifting (9.0% ± 1.2% prelift vs 6.6% ± 0.8% postlift; P = 0.005), whereas in exercise-trained individuals, FMD was unchanged (7.4% ± 0.7% prelift vs 8.0% ± 0.9% postlift; P = 0.543). With the protective cuff, FMD no longer decreased but rather increased in sedentary individuals (8.7% ± 1.2% prelift vs 10.5% ± 1.0% postlift, P = 0.025). An increase in FMD was also seen in exercise-trained subjects when the cuff was present (6.6% ± 0.7% prelift vs 10.9% ± 1.5% postlift, P < 0.001).Protecting the brachial artery from exercise-induced hypertension enhances FMD in sedentary and exercise-trained individuals. These results indicate that increased intraluminal pressure in the artery contributes to the reduced FMD after heavy resistance exercise in sedentary individuals.
Brachial artery
Cuff
Exertion
Sphygmomanometer
Perceived exertion
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BACKGROUNDThe age-associated decline in aerobic exercise capacity is partially reversible by endurance exercise training. Moderate-intensity endurance exercise training increases aerobic exercise capacity mediated, in part, by improvement of stroke volume and left ventricular performance in older men. The present study was designed to characterize the nature of cardiovascular adaptations to strenuous endurance exercise of long duration and to delineate the mechanisms underlying increased stroke volume and cardiac output in highly trained older endurance athletes.METHODS AND RESULTSNine male master athletes (MA: 64 +/- 2 years old, mean +/- SEM) and 9 older sedentary healthy men (controls: 63 +/- 1 year) were studied. Left ventricular systolic function was evaluated with the use of cardiac blood pool imaging and echocardiography. Maximal O2 uptake (VO2max) was 50.4 +/- 1.7 mL.kg-1 x min-1 in the MA and 29.6 +/- 1.4 mL.kg-1 x min-1 (P = .0001) in controls. Systolic and mean blood pressures at rest and durin...
Endurance Training
Aerobic Exercise
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Background: Non-electrocardiographic parameters obtained from exercise testing, including exercise capacity, exercise blood pressure, chronotropic response, and heart rate recovery, are clinically useful in determining prognosis in asymptomatic individuals. We hypothesized a relationship between post-exercise blood pressure (BP) and CVD mortality. Methods and results: After performing submaximal Bruce treadmill tests, a total of 6,451 asymptomatic North American study participants (56% males, mean age 44) from the Lipid Research Clinic Prevalence Study were prospectively followed for 20 years (366 CVD deaths). Post-exercise BP was the measured BP taken after ceasing exercise for 2 min, 4 min, and 6 min for systolic (SBP) and diastolic (DBP). The association of CVD mortality was stronger for post-exercise SBP (4 min age- and sex-adjusted hazard ratio 1.42 [95% CI, 1.28-1.55] per 1-SD increment [21 mmHg]) than post-exercise DBP (1.26 [1.14-1.38] per 1-SD increment [12 mm Hg]). After multivariate adjustment, post-exercise DBP was not associated with CVD mortality. By contrast, post-exercise 2 min, 4 min, and 6 min SBP were each positively associated with CVD mortality, with the post-exercise 4 min SBP having the greatest magnitude of risk. After adjusting for standard risk factors, baseline BP, heart rate recovery, and exercise capacity, the adjusted hazard ratios (95% CIs) for increasing quartiles of post-exercise 4 min SBP were 1.00 (reference), 1.47 (0.94-2.31), 1.75 (1.15-2.66) and 2.21 (1.43-3.43), p for trend<0.001 (Table). Conclusion: Elevated post-exercise SBP was significantly associated with CVD mortality in asymptomatic individuals independent of other risk factors, including baseline BP. A post-exercise 4 min SBP greater than 150 mmHg identifies higher risk individuals who may warrant more aggressive treatment than is currently recommended.
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Hemodynamic shear stress, a frictional force of blood on the arterial wall, decreases with aging. The reduction in shear stress involved in development and progression of vascular endothelial dysfunction, a risk factor of cardiovascular disease. Habitual exercise is an effective strategy to improve vascular endothelial function. However, the effect of habitual exercise on the resting shear stress is unknown. The aim of this study was to determine whether brachial artery shear stress correlates with exercise habituation in middle aged and older adults. A total of 112 healthy middle aged and older adults (50–76 years) participated in this study. We measured peak and mean brachial artery shear rates, as indices of shear stress, at rest. Daily step counts and maximum oxygen consumption (VO 2max ) were measured as an index of exercise habituation. Subjects were divided into the inactive group (< 7500 steps/day) and the active group (蠅 7500 steps/day). VO 2max was significantly higher in the active group than in the inactive group (P < 0.01). Peak shear rate and mean shear rate in the active group were significantly higher than in the inactive group (P < 0.01 and P < 0.05). VO 2max correlated significantly with peak (r = 0.362, P < 0.01) and mean shear rates (r = 0.302, P < 0.05). These associations were remained significant even when adjusted for age. These results suggest that habitual exercise may increase resting brachial artery shear stress in middle‐aged and older adults.
Brachial artery
Endothelial Dysfunction
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Aquatic exercise is ideal for older adults because it mitigates weight-bearing stress. However, the effect of head-out aquatic exercise on arterial stiffness, a strong future cardiovascular disease (CVD) risk, remains unclear. We determined whether head-out aquatic exercise would mitigate arterial stiffness in middle-aged and elderly people. In 25 middle-aged and older people (9 men, mean age 64 ± 8 years), blood pressure (BP) and brachial-ankle pulse wave velocity (baPWV) were measured before and after a supervised aquatic exercise training program (60 min, 1 session/week, 14 sessions) which mainly consisted of walking, stretching, and muscle strengthening in water. In the pooled subjects, systolic BP tended to decrease (<i>p</i> = 0.07) after the training intervention, whereas no significant changes were observed, including baPWV (from 1,537 ± 301 to 1,496 ± 308 cm/s). In the sub-analysis, by dividing subjects into a healthy group (<i>n</i> = 13) and a CVD risk group (<i>n</i> = 12), no significant interaction between time and group was seen in BP. On the other hand, baPWV decreased significantly in the healthy group (from 1,476 ± 299 to 1,365 ± 215 cm/s) but not in the CVD risk group (from 1,603 ± 301 to 1,637 ± 339 cm/s). The current study demonstrates that regular head-out aquatic exercise, even at a low frequency, could mitigate CVD risk in apparently healthy middle-aged and older people.
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Physiological blood flow velocity in common carotid artery (CCA) is altered markedly with advancing age. It is unknown that regular aerobic exercise is able to improve blood flow velocity waveforms in either healthy young or healthy older individuals. We investigate the role of regular exercise on the age-associated alterations in blood velocity waveforms in CCA by using cross-sectional and intervention approaches. First, we study 91 putatively healthy volunteers with age range of 20-76 years: 65 subjects are sedentary and 26 subjects are regular exercisetrained. We assess the blood velocities at rest in peak systolic (S1), second systolic (S2), incisura between systole (I) and peak diastolic (D), and end-diastolic (d) in young, middle-aged and older subjects. Blood velocities in S1 are higher in exercise-trained, whereas S2, D and d are not different between trained and sedentary individuals. However, the indices of S1/S2 and D/I have marked higher values in exercise-trained adults. Second, we study 7 young sedentary healthy subjects before and after 1-month aerobic exercise intervention. The aerobic exercise increases whole velocity waveforms in CCA with association of decreased heart rate. In conclusion, regular exercise improves age-associated decrease in blood flow velocities in the healthy young, middle-aged and older individuals and restores levels after 1-month exercise in previously sedentary young men.
Aerobic Exercise
Systole
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