Aerobic exercise performance correlates with post-ischemic flow-mediated dilation of the brachial artery in young healthy men

NIRS-Derived Muscle-Deoxygenation and Microvascular Reactivity During Occlusion-Reperfusion at Rest Are Associated With Whole-Body Aerobic Fitness

Purpose: Near-infrared spectroscopy (NIRS) indices during arterial occlusion-reperfusion maneuver have been used to examine the muscle's oxidative metabolism and microvascular function-important determinants of whole-body aerobic-fitness. The association of NIRS-derived parameters with whole-body VO2max was previously examined using a method requiring exercise (or electrical stimulation) followed by multiple arterial occlusions. We examined whether NIRS-derived indices of muscle deoxygenation and microvascular reactivity assessed during a single occlusion-reperfusion at rest are (a) associated with maximal/submaximal indices of whole-body aerobic-fitness and (b) could discriminate individuals with different VO2max. We, also, investigated which NIRS-parameter during occlusion-reperfusion correlates best with whole-body aerobic-fitness. Methods: Twenty-five young individuals performed an arterial occlusion-reperfusion at rest. Changes in oxygenated- and deoxygenated-hemoglobin (O2Hb and HHb, respectively) in vastus-lateralis were monitored; adipose tissue thickness (ATT) at NIRS-application was assessed. Participants also underwent a maximal incremental exercise test for VO2max, maximal aerobic velocity (MAV), and ventilatory-thresholds (VTs) assessments. Results: The HHbslope and HHbmagnitude of increase (occlusion-phase) and O2Hbmagnitude of increase (reperfusion-phase) were strongly correlated with VO2max (r = .695-.763, p < .001) and moderately with MAV (r = .468-.530; p < .05). O2Hbmagnitude was moderately correlated with VTs (r = .399-.414; p < .05). After controlling for ATT, the correlations remained significant for VO2max (r = .672-.704; p < .001) and MAV (r = .407; p < .05). Individuals in the high percentiles after median and tritile splits for HHbslope and O2Hbmagnitude had significantly greater VO2max vs. those in low percentiles (p < .01-.05). The HHbslope during occlusion was the best predictor of VO2max. Conclusion: NIRS-derived muscle deoxygenation/reoxygenation indices during a single arterial occlusion-reperfusion maneuver are strongly associated with whole-body maximal indices of aerobic-fitness (VO2max, MAV) and may discriminate individuals with different VO2max.

Various patterns of disrupted daily rest-activity rhythmicity associated with diabetes

Disruptions to sleep and circadian rhythms have now been recognized as common comorbidities in patients with medical illnesses. We aimed to determine if the diurnal rhythms for rest and activity were disrupted in parallel with the development of diabetic complications. Ninety outpatients in our diabetes clinic who had a body mass index <25 kg m(2) wore an actigraph for 7 consecutive days (42 men; mean age 68.7 ± 8.2 years). Patients with neuropsychiatric diseases, liver cirrhosis, renal failure, chronic obstructive pulmonary disease or blindness, or those who performed shiftwork were excluded. We grouped the actigraph recordings into 1-h periods and counted the number of minutes that showed activity. Stepwise regression analysis showed an association between a diabetic clinical background and measurements of circadian rhythms such as daytime activity, night-time activity, phase, interdaily stability, intradaily variability and relative amplitude. Higher age, body mass index, total cholesterol levels and insulin usage were associated with lower daytime activity and higher intradaily variability, whereas higher haemoglobin A1c levels and the presence of neuropathy were associated with greater daytime activity. The presence of proliferative retinopathy and increased levels of microalbuminuria were associated with higher intradaily variability and lower interdaily stability and amplitude. The presence of cardiovascular disease was associated with advanced phase, whereas painful neuropathy was associated with delayed phase. Our study demonstrated that different diabetic complications were associated independently with a variety of alterations in the circadian rest and activity rhythms. Our findings have provided novel insights that may be helpful in developing interventions for sleep-wake disorders associated with diabetes.

Exercise training augments regional bone and marrow blood flow during exercise

INTRODUCTION

The principal nutrient artery to the femur demonstrates an increase in nitric oxide-mediated vasodilation in rats after treadmill exercise training. The present study sought to determine whether exercise training improves hindlimb bone and marrow blood flow distribution at rest and during exercise.

METHODS

Six 8-month old male Sprague-Dawley rats were exercise trained (ET) with treadmill walking at 15 m · min(-1) up a 15° incline for 60 min · d(-1) over a 10- to 12-wk period. Sedentary (SED) control animals were acclimated to treadmill exercise for 5 min · d(-1) during the week preceding the blood flow measurements. Blood flow to nine distinct regions of the femur, tibia, and fibula was determined at rest and during low-intensity exercise (15 m · min(-1) walking, 0° incline) using the reference sample microsphere method.

RESULTS

The results demonstrate an augmentation of exercise hyperemia above that observed in SED rats during exercise in only one region of the bone, the femoral diaphysis, of ET rats. However, whereas exercise hyperemia occurred in three of the nine hindlimb bone regions measured in SED rats, exercise hyperemia occurred in seven of nine regions in ET rats.

CONCLUSIONS

These data indicate an increase in generalized hindlimb bone and marrow blood flow during physical activity after a period of exercise training. Elevations in regional bone and marrow blood flow after training may augment medullary pressure and bone interstitial fluid flow, thus benefiting bone integrity.

The association of cardiorespiratory fitness with endothelial or smooth muscle vasodilator function

BACKGROUND

Maximal oxygen consumption (VO2max) is strongly associated with peripheral vasodilator function as determined by exercise-induced vasodilation. However, findings with regard to its relation with non-exercise-stimulated vasodilation are unclear. The purpose of this study was to systematically review published literature reporting associations between VO2max and endothelial function (EF) or smooth muscle function (SMF).

DESIGN AND METHODS

We conducted a systematic search of MEDLINE, Cochrane and Web of Science, since their inceptions until April 2014 for articles reporting the association between (a) VO2max during incremental exercise and (b) endothelium-dependent or -independent vasodilator function, by means of correlation and/or regression analysis.

RESULTS

Fifty-six articles exploring 88 associations between VO2max and vascular EF or SMF were included, involving a total of 4159 healthy and diseased subjects. VO2max was determined by incremental cycle ergometer (64%), treadmill (33%) and cycle ergometer/treadmill (3%) exercise. Vasodilator function variables were assessed in the upper limb (86%), lower limb (10%) and both upper and lower limbs (3%). Most of the evaluated bivariate associations involved EF stimuli such as flow-mediated dilation (FMD) (n = 29) or blood flow occlusion (BFO) (n = 18). VO2max was significantly associated with FMD and BFO in 59% and 67% of bivariate associations and 46% and 33% of age-independent associations, respectively. Explored bivariate associations regarding SMF involved sodium nitroprusside (SNP) iontophoresis (n = 7) and nitrate-mediated dilation (NMD) (n = 4). VO2max was associated with NMD in 50% of bivariate associations and 50% of age-independent associations. VO2max was not associated with SNP iontophoresis. Results were similar for associations including only healthy subjects.

CONCLUSIONS

The association between VO2max and EF or SMF is moderately frequent and independent of health status, despite very few studies having assessed vasodilator function in the lower limb.

Higher mean blood pressure is associated with autonomic imbalance but not with endothelial dysfunction in young soccer players

BACKGROUND

Blood pressure (BP) should be kept within a narrow range to allow adequate tissue perfusion. In particular, heart-rate variability (HRV) can be used to assess autonomic cardiovascular modulation, and flow-mediated dilation (FMD) can provide valuable information about the ability of the cardiovascular system to adapt to different pressures. Our objective in the study described here was to investigate the effect of a difference of 10mm Hg in mean arterial pressure (MAP) on endothelial function and autonomic balance in young and normotensive soccer players.

METHODS

Twenty-nine young male soccer players (mean age 17.7 years) were divided into two groups according to their MAP (mm Hg): MAP-84 and MAP-94. The BP, FMD, HRV and maximum oxygen uptake (VO2max) of each group were measured.

RESULTS

Systolic BP (SBP) and diastolic BP (DBP) were significantly higher (P < 0.0001 and P < 0.006, respectively) in the MAP-94 group. There were no differences in VO2max and endothelial function in the two groups (P < 0.7699). However, the standard deviation (SD) of normal RR intervals (SDNN) and the square root of the mean squared differences in successive RR intervals (RMSSD) were significantly lower in the MAP-94 than in the MAP-84 group (P < 0.0001 and P < 0.005, respectively). In the MAP-94 group, both the high-and low-frequency components were significantly (P < 0.001, P < 0.021, P < 0.017, respectively) lower in both absolute and normalized units, whereas the LF/HF ratio was significantly (P < 0.012) higher.

CONCLUSIONS

Collectively, our findings indicate that in young soccer players, autonomic cardiovascular modulation is impaired when MAP is increased by 10mm Hg, even within an optimal range of BP and regardless of endothelial function and VO2max.

Predictors of improvement in endothelial function after exercise training in a diverse sample of postmenopausal women

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/m(2)) and 16 Caucasian (age: 57.2±5.9 years, VO2 peak: 21.8±3.7 mL/kg/minute, BMI: 29.3±5.2 kg/m(2)) 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.

Poor Aerobic Fitness May Contribute to Cognitive Decline in HIV-infected Older Adults

The HIV-infected older adult (HOA) community is particularly vulnerable to cognitive impairment. Previous studies in the general older adult population have reported that lower scores on tests of cognitive function often correlate negatively with aerobic fitness [5-7]. HIV-infected individuals have significantly reduced aerobic fitness and physical function compared to HIV-uninfected individuals. Determining important correlates of cognitive ability may be beneficial in not only detecting precursors to future cognitive impairments, but also target areas for interventions. The purpose of this study was to investigate the relationship between cognitive ability and aerobic fitness in HIV-infected older adults. We conducted a cross-sectional study of HOA on antiretroviral therapy (ART) >50 years of age. Domain specific cognitive function was assessed by means of a neuropsychological battery. Aerobic fitness (VO2peak) was assessed using a graded, progressive treadmill test. Thirty-seven HOA on ART (mean±SD: age 59±6 years, BMI 28±5, CD4 663±337 cells/ml, duration since HIV diagnosis 17±7 years; 81% males) completed the cognitive tests. Several domains of cognition were significantly associated with VO2peak by Spearman correlation analysis (p<0.05). By step-wise adjusted regression VO2peak was most frequently and significantly related to many cognitive domains such as verbal and visual memory, visual perception, and language (p<0.05). We found that participants with higher Vo2peak were less likely to have more severe forms of HIV-associated neurocognitive disorders (HAND) such as mild neurocognitive disorder (OR=0.65; p=0.01) and HIV-associated dementia (OR=0.64; p=0.0006). In HOA and in conclusion, aerobic fitness is related to cognitive performance on various tasks. The likelihood of cognitive impairment increased with lower fitness levels. Therefore, increased fitness may serve an important factor in maintenance of cognition and neural integrity for aging HIV-infected individuals. Future prospective and large scale studies are needed to evaluate the effect of fitness and vascular stiffness and function on cognition and brain structure among HOA.

Peripheral endothelial dysfunction is associated with gas exchange inefficiency in smokers

Aims

To assess the cross-sectional association between exercise capacity, gas exchange efficiency and endothelial function, as measured by flow-mediated dilation (FMD) and nitroglycerin-mediated dilation (NMD) of the brachial artery, in a large-scale population-based survey.

Methods

The study population was comprised of 1416 volunteers 25 to 85 years old. Oxygen uptake at anaerobic threshold (VO₂@AT), peak exercise (peakVO₂) and ventilatory efficiency (VE vs. VCO₂ slope and VE/VCO₂@AT) were assessed on a breath-by-breath basis during incremental symptom-limited cardiopulmonary exercise. FMD and NMD measurements at rest were performed using standardised ultrasound techniques.

Results

Multivariable logistic regression analyses revealed a significant association between FMD and ventilatory efficiency in current smokers but not in ex-smokers or non-smokers. There was no association between FMD and VO₂@AT or peak VO₂. In current smokers, for each one millimetre decrement in FMD, VE/VCO₂@AT improved by -3.6 (95% CI -6.8, -0.4) in the overall population [VE vs. VCO₂ slope -3.9 (-7.1, -0.6)]. These results remained robust after adjusting for all major influencing factors. Neither exercise capacity nor ventilatory efficiency was significantly associated with NMD.

Conclusion

In current smokers, FMD is significantly associated with ventilatory efficiency. This result may be interpreted as a potential clinical link between smoking and early pulmonary vasculopathy due to smoking.

Acetaminophen increases blood pressure in patients with coronary artery disease

BACKGROUND

Because traditional nonsteroidal antiinflammatory drugs are associated with increased risk for acute cardiovascular events, current guidelines recommend acetaminophen as the first-line analgesic of choice on the assumption of its greater cardiovascular safety. Data from randomized clinical trials prospectively addressing cardiovascular safety of acetaminophen, however, are still lacking, particularly in patients at increased cardiovascular risk. Hence, the aim of this study was to evaluate the safety of acetaminophen in patients with coronary artery disease.

METHODS AND RESULTS

The 33 patients with coronary artery disease included in this randomized, double-blind, placebo-controlled, crossover study received acetaminophen (1 g TID) on top of standard cardiovascular therapy for 2 weeks. Ambulatory blood pressure, heart rate, endothelium-dependent and -independent vasodilatation, platelet function, endothelial progenitor cells, markers of the renin-angiotensin system, inflammation, and oxidative stress were determined at baseline and after each treatment period. Treatment with acetaminophen resulted in a significant increase in mean systolic (from 122.4±11.9 to 125.3±12.0 mm Hg P=0.02 versus placebo) and diastolic (from 73.2±6.9 to 75.4±7.9 mm Hg P=0.02 versus placebo) ambulatory blood pressures. On the other hand, heart rate, endothelial function, early endothelial progenitor cells, and platelet function did not change.

CONCLUSIONS

This study demonstrates for the first time that acetaminophen induces a significant increase in ambulatory blood pressure in patients with coronary artery disease. Thus, the use of acetaminophen should be evaluated as rigorously as traditional nonsteroidal antiinflammatory drugs and cyclooxygenase-2 inhibitors, particularly in patients at increased cardiovascular risk.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00534651.

Relation of flow-mediated dilation to global arterial load: impact of hypertension and additional cardiovascular risk factors

BACKGROUND

Endothelial dysfunction may be related to increased left ventricular (LV) mass due to an association between endothelial dysfunction with increased arterial load. Therefore, we evaluated whether brachial artery flow-mediated dilation (FMD) is related to global arterial load.

METHODS

Pulse pressure/stroke index (PP/SVi, global arterial stiffness, prognostically validated), stroke volume/PP (SV/PP, global arterial compliance), and % of the predicted SV/PP by heart rate, age and body weight (confounder-adjusted global compliance, prognostically validated) were used as LV geometry-related indices of global arterial load.

RESULTS

Compared to normotensive participants (NT, n = 50), those with hypertension (HTN, n = 51) had lower FMD (8.3% ± 5.4 vs. 12.8% ± 6.5), higher PP/SVi (1.24 ± 0.34 vs. 1.04 ± 0.28 mmHg m(2)/ml), higher LV mass and higher relative wall thickness (all p < 0.01); in contrast, SV/PP and % of predicted SV/PP did not differ between NT and HTN (all p>0.1). Impaired FMD was 3-4-fold more prevalent than LV hypertrophy or increased arterial load both in NT and in HTN. Within NT and HTN separately, PP/SVi, SV/PP and % of predicted SV/PP were comparable among tertiles of FMD. Only in NT, lower FMD was associated with higher peak exercise systolic BP (p < 0.05). In multivariable regression models, FMD was not associated with indices of arterial load independently (all p > 0.1).

CONCLUSIONS

In young-to-middle-age subjects with cardiovascular risk factors, impaired FMD is more prevalent than traditional preclinical manifestation of cardiovascular disease, and may exist independent to increased arterial load. Thus, endothelial dysfunction assessment may refine cardiovascular risk profile and risk-reduction strategies based on detection of traditional target organ damage.

Hypertension update and cardiovascular risk reduction in physically active individuals and athletes

Hypertension is a prevalent disease worldwide. Its inadequate treatment leads to major cardiovascular complications, such as myocardial infarction, stroke, and heart failure. These conditions decrease life expectancy and are a substantial cost burden to health care systems. Physically active individuals and professional athletes are not risk free for developing this condition. Although the percentage of persons affected is substantially lower than the general population, these individuals still need to be thoroughly evaluated and blood pressure targets monitored to allow safe competitive sports participation. Regarding treatment, lifestyle modification measures should be routinely emphasized to athletes and active individuals with the same importance as for the general population. Medication treatment can be complicated because of restrictions by athletic organizations and possible limitations on maximal exercise performance. In addition, the choice of an antihypertensive drug should be made with consideration for salt and water losses that routinely occur in athletes, as well as preservation of exercise performance and endothelial function. First-line therapies for athletes and physically active individuals may be different from the general population. Some authorities believe that blocking the renin-angiotensin system with angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs) is more beneficial compared with diuretics because of ACE inhibitors and ARBs being able to avoid salt and water losses. Dihydropyridine calcium channel blockers (CCBs) are another reasonable choice. Despite effects on heart rate, nondihydropyridine CCBs do not appear to impair exercise performance. beta-Blockers are not used as a first-line therapy in athletes because of effects on exercise and prohibition by the National Collegiate Athletic Association and World Anti-Doping Agency in certain sports. In this article, we address the evidence on hypertension and its related treatments in active individuals to provide recommendations that allow the best competitive sports results and reduce cardiovascular risk.

Vascular remodeling in response to 12 wk of upper arm unilateral resistance training

Participation in regular aerobic exercise has been shown to increase arterial size and that exercise-induced vascular remodeling may be regional rather than systemic. However, these issues have been minimally investigated concerning resistance training.

PURPOSES

To determine whether 1) resistance training of the nondominant arm elicits an increase in diameter of the brachial artery and 2) unilateral training induces arterial remodeling in the contralateral arm.

METHODS

Twenty-four previously untrained participants, consisting of 18 females (aged 22.3 +/- 5.1 yr) and 6 males (aged 21.7 +/- 1.8 yr), participated in unilateral strength training of the biceps and triceps for 12 wk using their nondominant arm. Isotonic (one-repetition maximum, 1RM) and isometric (ISO) strength of the biceps were assessed before and after training on both arms. Brachial artery diameter and biceps muscle cross-sectional area (CSA) of both arms were also measured before and after training using magnetic resonance imaging (MRI).

RESULTS

Brachial artery diameter increased 5.47% (P < 0.05) in the nondominant trained arm with no change observed in the dominant untrained arm. Biceps CSA increased 18.3% (P < 0.05) in the trained arm with no change (P > 0.05) in the untrained limb. Nondominant 1RM and ISO strength increased by 35.1% and 16.8%, respectively (P < 0.05 for both), although there were no significant changes (P > 0.05) in the contralateral arm. A modest correlation was found between the increases in CSA and in brachial artery diameter (r2 = 0.19, P = 0.039).

CONCLUSIONS

These results indicate that upper arm vascular remodeling, manifesting as increased brachial artery diameter, can result from resistance training and that these changes are localized to the trained limb and associated with increases in CSA.

Changes in blood flow in a conduit artery and superficial vein of the upper arm during passive heating in humans

The purposes of this study were (1) to evaluate changes in blood flow in the brachial artery and basilic vein of the upper arm with a rise in internal temperature during passive heating; and (2) to investigate the contributions of blood velocity and anteroposterior vessel diameter to these blood flow changes. Ten subjects rested in the supine position between a pair of tube-lined sheets. Thermoneutral water was circulated through the tubes to keep a mean skin temperature (Tsk) of 34-35 degrees C, and then hot water was circulated to maintain Tsk of 37-38 degrees C. The blood velocity and diameter in the brachial artery and basilic vein were continuously monitored by Doppler ultrasound technique and used to calculate blood flow. Blood flow in the brachial artery and basilic vein increased linearly as the oral temperature (T(or)) rose by < or =0.6 degrees C. The magnitude of the change in blood flow did not differ significantly between the two vessels. In addition, plots of DeltaT(or) versus blood flow yielded slopes that did not differ significantly between the brachial artery and the basilic vein. As T (or) increased, blood velocity, but not diameter, also increased. In conclusion, blood flow in the brachial artery and the basilic vein increased linearly as the internal temperature variable T (or) increased < or =0.6 degrees C. In both vessels, the passive heating-induced increases in blood flow resulted primarily from a change in blood velocity, rather than from a change in diameter.

The relationship between flow-mediated dilatation and left ventricular function in type 2 diabetic patients with microalbuminuria

OBJECTIVE

The aim of this study was to assess the relationship between flow-mediated dilatation (FMD) and left ventricular (LV) systolic and diastolic function in type 2 diabetic patients with or without microalbuminuria.

RESEARCH DESIGN AND METHODS

We prospectively evaluated 68 consecutive patients (36 women, 32 men; mean age 57 +/- 11 yr) with type 2 diabetes mellitus (DM). Patients were divided into two groups according to whether or not they had microalbuminuria: group 1 (n = 29, mean age 58 +/- 10 yr) with microalbuminuria and group 2 (n = 39, mean age 56 +/- 10 yr) without microalbuminuria. LV function was assessed by classical methods and Doppler tissue imaging (DTI). Left ventricular ejection fraction (EF), interventricular (IVS) and posterior wall (PW) thickness, peak early (E) and late (A) transmitral filling velocities, their ratio (E/A) and deceleration time of the mitral E wave (DT), LV isovolumetric relaxation time (IVRT), flow propagation of velocity (Vp), and E/Vp were evaluated by conventional echocardiography. Early diastolic (Em), late diastolic (Am), and peak systolic (Sm) mitral annular velocities were measured. Em/Am and the ratio of early diastolic mitral inflow velocity to Em (E/Em), which is a reasonably good index for predicting elevated LV filling pressure, were calculated by DTI. Endothelial function, measured as flow-mediated dilatation of the brachial artery using ultrasound, was calculated in two groups.

RESULTS

FMD was lower in those with microalbuminuria than those without (8.8 +/- 6.44% vs 12.6 +/- 7.24%, p = 0.03). Group 1 had longer DT (223 +/- 39 ms vs 199 +/- 37 ms, p = 0.01) and longer IVRT (109 +/- 13 ms vs 100 +/- 13 ms, p = 0.03) than that of group 2 with conventional echocardiography. Group 1 had significantly lower Em/ Am (0.79 +/- 0.27 cm/s vs 1.02 +/- 0.44 cm/s, p = 0.01), lower Vp (40.4 +/- 9.98 vs 50.4 +/- 19.01 cm/s, p = 0.01) than that of group 2. Group 1 had significantly higher serum creatinine (1 +/- 0.33 mg/dL vs 0.7 +/- 0.19, p = 0.001). In logistic regression analysis, FMD was the only variable independently related to microalbuminuria. FMD was positively correlated with EF (r = 0.43, p = 0.02) and E/A (r = 0.40, p = 0.03), and negatively correlated with E/Em (r = 0.41, p = 0.04) and E/Vp (r = 0.41, p = 0.04) only in patients with microalbuminuria.

CONCLUSION

It was found that left ventricular diastolic function and FMD are impaired in type 2 diabetic patients with microalbuminuria. FMD may be related to LV diastolic dysfunction only in patients with microalbuminuria.

Association between post-ischemic forearm blood flow and blood pressure response to maximal exercise in well trained healthy young men

BACKGROUND

The relationship between peripheral circulation and blood pressure (BP) response to maximal exercise is an intriguing and not yet well defined topic.

AIMS

Aims of the present study were to investigate in well trained young healthy males the possible relationships between the endothelial or the smooth muscle component of the peripheral circulation and 1) the BP response to physical exercise on treadmill 2) the body mass composition.

SUBJECTS AND METHODS

Fifteen subjects (18-36 years), regularly performing physical activity 3 times weekly underwent the following examinations: body composition by bioelectrical impedance analysis; measurement of the forearm blood flow (FBF) at rest and during post-ischemic hyperemia by strain-gauge plethysmography at the upper arm; measurement of brachial artery diameter (BAD) at rest and after 4-min ischemia by echography; BP response to maximal exercise on treadmill with the determination of maximal oxygen consumption and the measurement of lactic acid serum concentration.

RESULTS

BAD was significantly increased during post-ischemic hyperemia up to the 4th minute of observation with a peak at 60 s (+8.5%); FBF increased at 30 s after ischemia (+210%) and returned to baseline levels at the 2nd minute. In the linear correlation analysis, systolic BP increase at the end of the maximal exercise was significantly and inversely related to the increase in FBF (r=-0.663, p<0.01) and to the early FMD (r=0.503, p<0.05). In the multiple regression analysis, however, only FBF independently affected SBP increase during exercise (t=-3.268, p<0.02). Systolic BP increase at the end of the maximal exercise was significantly related to the increase in FBF but not to that of BAD. Among parameters of body composition, fat-free mass was closely related to changes only in BAD.

CONCLUSIONS

These data indicate that FBF, which depends on the smooth muscle component of the peripheral circulation, is closely related to BP response to exercise while the endothelial function, which has been determined as changes in BAD, is related to the fat-free mass of the body, possibly through the peripheral insulin sensitivity.

Relations of left ventricular mass and systolic function to endothelial function and coronary flow reserve in healthy, new discovered hypertensive subjects

Left ventricular hypertrophy (LVH) is prognostically relevant, associated with major cardiovascular risk factors and with atherosclerosis. However, whether LVH is independently associated with impaired coronary flow reserve (CFR) and with endothelial dysfunction is disputed. We assessed the relationship of LV mass and systolic function to CFR and endothelial function in new discovered never treated subjects with essential arterial hypertension, but without coronary artery disease or microalbuminuria. LVH, ejection fraction (EF) and stress-corrected midwall shortening (MWS, a measure of myocardial contractility) were assessed by echocardiography. CFR was assessed by single-photon emission computed tomography and dipyridamole infusion. Endothelial function was evaluated by assessing 1-min postischaemic flow-mediated dilatation of the brachial artery (FMD); nitroglycerine-mediated dilatation (NMD) of the same brachial artery was used as measure of nonendothelium-dependent vasodilatation. In approximately 1 year, we enrolled 21 subjects who met stringent inclusion criteria (47+/-10 years old, 26.6+/-2.8 kg/m2, 78% men). Five patients showed LVH. Multivariate analyses showed a significant negative correlation of LV mass index with FMD (beta=-0.61, P<0.05) but not with NMD, neither with CFR. Stress-corrected MWS showed independent correlation with CFR (beta=0.51, P<0.05). Thus, in clinically healthy, new discovered hypertensive subjects, never treated and mostly in the early stage of arterial hypertension, LVH can be associated with endothelial dysfunction while maximal dipyridamole- dependent CFR may be preserved; nevertheless, a cardiac phenotype presenting with tendency to impaired myocardial contractility, assessed by stress-corrected MWS, showed association with lower CFR in the early stage of arterial hypertension.

Effects of different dietary protein intakes on body composition and vascular reactivity

OBJECTIVE

To assess the effects of a diet rich in protein of animal origin in comparison to one with a protein intake of about 15% of the total daily calories on body composition and arterial function.

DESIGN

Randomized prospective study with parallel groups. Body weight (BW), blood pressure (BP), main parameters of carbohydrate and lipid metabolism, body mass composition by bioelectrical impedance analysis, forearm blood flow at rest and in the postischaemic phase by strain gauge plethysmography and flow-mediated dilation of the brachial artery by echography were measured at baseline and after 6 months of the dietary intervention.

SUBJECTS

In total, 15 clinically healthy male volunteers, regularly performing a mixed training three times weekly for 90 min.

INTERVENTION

The participants were randomly prescribed a diet with high (1.9 g/kg BW) or normal (1.3 g/kg BW) protein content.

STATISTICAL ANALYSIS

Differences between means were evaluated by the t-tests for paired or unpaired data and by one way analysis of variance. The strength of correlation between variables was investigated by bivariate Pearson correlation.

RESULTS

Serum cholesterol significantly decreased with both diets in comparison to baseline values, whereas BW was slightly but significantly reduced only by the high-protein (HP) diet. No change was detected in BP and the other metabolic parameters. Body mass composition was not significantly modified by either diet. On the other hand, postischaemic flow-mediated dilation of the brachial artery was enhanced by the sole normal protein (NP) diet, whereas no change in the forearm blood flow, both at rest and in the postischaemic phase, was detected.

CONCLUSIONS

These preliminary results indicate that HP diet was found to be not useful in increasing the muscle mass in comparison to a NP intake. In contrast to this, the latter diet seems to enhance the endothelial function of the arterial vessels with a more pronounced dilatation of the lumen in response to the increase in blood flow.