***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Moderate-intensity endurance exercise training improves vascular endothelial vasomotor function ; however , the impact of high-intensity exercise training has been equivocal . Thus , the effect of the physiological stress of the exercise remains poorly understood . Furthermore , enhanced vascular repair mediated by circulating progenitor cells may also be improved . To address whether the physiological stress of exercise training is an important factor contributing to these adaptations , 20 healthy participants trained for 6 weeks . Training involved either moderate ( MSIT ; n= 9 ) or heavy metabolic stress ( HSIT ; n= 11 ) interval exercise training programmes matched for total work and duration of exercise . Before and after training , flow-mediated dilatation , low-flow-mediated constriction and total vessel reactivity were measured at the brachial artery using Doppler ultrasound . Circulating progenitor cells ( CD34 + , CD133 + and CD309/KDR+ ) were measured by flow cytometry ( means ± SD ) . Relative ( MSIT pre- 5.5 ± 3.4 versus post-training 6.6 ± 2.5 % ; HSIT pre- 6.6 ± 4.1 versus post-training 7.0 ± 3.4 % , P= 0.33 ) and normalized ( P= 0.16 ) flow-mediated dilatation did not increase with either training programme . However , low-flow-mediated constriction was greater after training in both groups ( MSIT pre- −0.5 ± 3.2 versus post-training −1.9 ± 3.1 % ; HSIT pre- −1.0 ± 1.7 versus post-training −2.9 ± 3.0 % , P= 0.04 ) and contributed to greater total vessel reactivity ( MSIT pre- 7.4 ± 3.3 versus post-training 10.1 ± 3.7 % ; HSIT pre- 10.9 ± 5.9 versus post-training 12.7 ± 6.2 % , P= 0.01 ) . Peak reactive hyperaemia and the area under the shear rate curve were not different between groups , either before or after training . Although circulating progenitor cell numbers increased following heavy-intensity interval exercise training , variability was great amongst participants [ MSIT pre- 16 ± 18 versus post-training 14 ± 12 cells ( ml whole blood)−1 ; HSIT pre- 8 ± 6 versus post-training 19 ± 23 cells ( ml whole blood)−1 , P= 0.50 ] . Overall , vasoconstrictor function may be augmented by moderate- and heavy-intensity interval exercise training in young adults . However , circulating progenitor cell numbers were not increased , suggesting that these cells are not likely to be upregulated as a result of training OBJECTIVES Our goal was to test feasibility and efficacy of a dietary intervention based on daily intake of flavanol-containing cocoa for improving vascular function of medicated diabetic patients . BACKGROUND Even in fully medicated diabetic patients , overall prognosis is unfavorable due to deteriorated cardiovascular function . Based on epidemiological data , diets rich in flavanols are associated with a reduced cardiovascular risk . METHODS In a feasibility study with 10 diabetic patients , we assessed vascular function as flow-mediated dilation ( FMD ) of the brachial artery , plasma levels of flavanol metabolites , and tolerability after an acute , single-dose ingestion of cocoa , containing increasing concentrations of flavanols ( 75 , 371 , and 963 mg ) . In a subsequent efficacy study , changes in vascular function in 41 medicated diabetic patients were assessed after a 30-day , thrice-daily dietary intervention with either flavanol-rich cocoa ( 321 mg flavanols per dose ) or a nutrient-matched control ( 25 mg flavanols per dose ) . Both studies were undertaken in a r and omized , double-masked fashion . Primary and secondary outcome measures included changes in FMD and plasma flavanol metabolites , respectively . RESULTS A single ingestion of flavanol-containing cocoa was dose-dependently associated with significant acute increases in circulating flavanols and FMD ( at 2 h : from 3.7 + /- 0.2 % to 5.5 + /- 0.4 % , p < 0.001 ) . A 30-day , thrice-daily consumption of flavanol-containing cocoa increased baseline FMD by 30 % ( p < 0.0001 ) , while acute increases of FMD upon ingestion of flavanol-containing cocoa continued to be manifest throughout the study . Treatment was well tolerated without evidence of tachyphylaxia . Endothelium-independent responses , blood pressure , heart rate , and glycemic control were unaffected . CONCLUSIONS Diets rich in flavanols reverse vascular dysfunction in diabetes , highlighting therapeutic potentials in cardiovascular disease An inverse relation exists between intake of flavonoid-rich foods , such as cocoa , and cardiovascular-related mortality . Favorable effects of flavonoids on the endothelium may underlie these associations . We performed a r and omized , double-blind , placebo-controlled study to test the hypothesis that acute cocoa ingestion dose dependently increases endothelium-dependent vasodilation , as measured by an increase in brachial artery flow-mediated dilation ( FMD ) , in healthy older adults . Measurements were obtained before ( preingestion ) and after ( 1- and 2-h postingestion ) ingestion of 0 ( placebo ) , 2 , 5 , 13 , and 26 g of cocoa in 23 adults ( 63 ± 2 yr old , mean ± SE ) . Changes in brachial artery FMD 1- and 2-h postingestion compared with preingestion were used to determine the effects of cocoa . FMD was unchanged 1 ( Δ-0.3 ± 0.2%)- and 2-h ( Δ0.1 ± 0.1 % ) after placebo ( 0 g cocoa ) . In contrast , FMD increased both 1-h postingestion ( 2 g cocoa Δ0.0 ± 0.2 % , 5 g cocoa Δ0.8 ± 0.3 % , 13 g cocoa Δ1.0 ± 0.3 % , and 26 g cocoa Δ1.6 ± 0.3 % : P < 0.05 compared with placebo for 5 , 13 , and 26 g cocoa ) and 2-h postingestion ( 2 g cocoa Δ0.5 ± 0.3 % , 5 g cocoa Δ1.0 ± 0.3 % , 13 g cocoa Δ1.4 ± 0.2 % , and 26 g cocoa Δ2.5 ± 0.4 % : P < 0.05 compared with placebo for 5 , 13 , and 26 g cocoa ) on the other study days . A serum marker of cocoa ingestion ( total epicatechin ) correlated with increased FMD 1- and 2-h postingestion ( r = 0.44 - 0.48 ; both P < 0.05 ) . Collectively , these results indicate that acute cocoa ingestion dose dependently increases brachial artery FMD in healthy older humans . These responses may help to explain associations between flavonoid intake and cardiovascular-related mortality in humans 
    Output:
    
Red blood cell velocity in arterioles and blood flow in the artery were significantly increased 5 min after the administration of 10 mg/kg flavan-3-ols compared with distilled water treatment .
The number of capillaries recruited in the cremaster muscle was also significantly increased 15 min after treatment .
Microscopic observation confirmed that increased shear stress on endothelial cells was maintained during the measurement period .
The mean arterial blood pressure and heart rate were also significantly elevated soon after administration and returned to baseline before the end of the observation period .
Plasma nitrate and nitrite levels , and NO phosphorylation of aortic tissue were significantly increased at 60 min after administration of flavan-3-ols .
According to these results , a single oral dose of flavan-3-ols elevates blood pressure and flow transiently , and these effects induce NO production through increased shear stress on endothelial cells