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Exercise elicits acute increases in cerebral blood flow velocity (CBFv) and provokes long-term beneficial effects on CBFv, thereby reducing cerebrovascular risk. Acute exposure to a cold stimulus also increases CBFv. We compared the impact of exercise training in cold and thermoneutral environments on CFBv, cerebrovascular function and peripheral endothelial function.\ud Twenty-one (16 males, 22 ± 5 years) individuals were randomly allocated to either a cold (5 °C) or thermoneutral (15 °C) exercise intervention. Exercise consisted of 50-min cycling at 70% heart rate max, three times per week for eight weeks. Transcranial Doppler was used to determine pre and post intervention CBFv, dynamic cerebral autoregulation (dCA) and cerebrovascular reactivity (CVRCO2). Conduit endothelial function, microvascular function and cardiorespiratory fitness were also assessed.\ud Cardiorespiratory fitness improved (2.91 ml.min.kg−1, 95%CI 0.49, 5.3; P = 0.02), regardless of exercise setting. Neither intervention had an impact on CBFv, CVRCO2, FMD or microvascular function (P > 0.05). There was a significant interaction between time and condition for dCA normalised gain with evidence of a decrease by 0.192%cm.s−1.%mmHg−1 (95%CI -0.318, −0.065) following training in the cold and increase (0.129%cm.s−1.%mmHg−1, 95%CI 0.011, 0.248) following training in the thermoneutral environment (P = 0.001). This was also evident for dCA phase with evidence of an increase by 0.072 rad (95%CI -0.007, 0.152) following training in the cold and decrease by 0.065 (95%CI -0.144, 0.014) radians following training in the thermoneutral environment (P = 0.02).\ud Both training interventions improved fitness but CBFv, CVRCO2 and peripheral endothelial function were unaltered. Exercise training in the cold improved dCA whereas thermoneutral negated dCA.

To the Editor: Surgical implantation of electrodes into deep brain structures for the management of conditions such as chronic pain provides an opportunity for assessment of the physiological impact of stimulation of focal brain nuclei in humans.1 Recent studies in humans have suggested that stimulation of the periventricular (PVG)/periaqueductal grey (PAG) regions can result in changes in systemic blood pressure (BP).2,3 In the present case, we examined the physiological impact of such stimulation in humans by obtaining continuous measures of limb blood flow, peripheral resistance, stroke volume, and heart rate (HR) during deep brain stimulation (DBS) of the PVG/PAG. The patient, a 55-year–old woman, was referred for management of recalcitrant chronic neuropathic, phantom limb pain (affecting both lower limbs) in 2004, subsequently leading to PVG/PAG DBS surgery in 2005 at the Radcliffe Infirmary in Oxford. Assessments and procedures were approved by the Oxford Ethics Committee and performed in a quiet thermostatically controlled room (26°C). The patient was placed in a semirecumbent position, at which point the stimulator was turned off for an initial 20-minute rest period. After a baseline BP assessment using a Finometer PRO (Finapres Medical Systems, Amsterdam, Netherlands), the stimulator was turned on, and BP, stroke volume, total peripheral resistance, and brachial artery diameter and blood flow velocity (Terason T3000, Teratech …

Some evidence suggests that sedentary behaviour is independently associated with cardiovascular (CV) risk. Endothelial dysfunction is the earliest detectable manifestation of CVD and a strong independent predictor of CV events. No previous study has examined the relationship between sedentary behaviour and endothelial function. We assessed the basal association between conduit artery endothelial function and sedentary behaviour in children, along with the correlation between changes in sedentary behaviour and endothelial function. We studied 116 children (70♀: 10.7 ± 0.3; 46♂: 10.7 ± 0.3 years) on two occasions; in the summer (June) and late autumn (November). We assessed endothelial function via flow-mediated dilation (FMD) using high-resolution Doppler ultrasound. Sedentary behaviour (SB) was assessed using objective uni-axial accelerometry. At baseline, there were no significant differences between girls and boys for any measured variables with the exception of total physical activity time. FMD was not associated with sedentary behaviour in either group or in the cohort as a whole. Although FMD decreased (10.0 ± 4.3–7.9 ± 3.9%, P

To the Editor: Standards relating to the assessment of subclinical atherosclerosis in children are important, especially given the large variation that exists in the “normative” data being published. This variability can, at least in part, be ascribed to variability and inconsistency in the application of the technique. Unfortunately, the Statement recently published in Hypertension 1 ignores a large and established literature related to improving methods of assessment of flow-mediated dilation (FMD). For example, literature developed across the past decade and summarized by Pyke and Tschakovsky2 has focused on appropriate assessment and quantification of the stimulus responsible for FMD. Ignoring the shear stress …

Background The prevalence of obesity and physical inactivity in Western countries has increased rapidly. Both are modifiable risk factors for cardiovascular disease. Atherosclerosis begins in childhood and endothelial dysfunction is its earliest detectable manifestation. Methods We assessed flow-mediated dilation (FMD) in 129 children (75 female; 10.3+0.3yrs; 54 male; 10.4; 0.3yrs). FMD was normalised for differences in the eliciting shear rate stimulus between subjects (SR AUC ). Fitness was assessed as peak oxygen uptake during an incremental treadmill exercise test ( V ˙ O 2 peak). Body composition was measured using a dual-energy X-ray absorptiometry (DEXA) scan. Physical activity (PA) was assessed using Actigraph accelerometers. The cohort was split into tertiles according to FMD% and also FMD% corrected for SR AUC to gain insight into the determinants of vascular function. Results Across the cohort, significant correlations were observed between FMD%/SR AUC and DEXA percentage fat ( r =−0.23, p =0.009) and percentage lean mass ( r =0.21, p =0.008), and also with PA performed at moderate-to-high intensity ( r =0.363, p =0.001). For children in the lowest FMD%/SR AUC tertile, a stronger relationship with all PA measures was observed, particularly with high intensity PA ( r =0.572, P =0.003). Regression analysis revealed that high intensity PA was the only predictor of impaired FMD%/SR AUC . Conclusions These data suggest that traditional risk factors for CHD in adult populations impact upon vascular function in young people. Furthermore, it appears that individuals with impaired FMD may benefit from performing high intensity PA, whereas no relationships exist between FMD and lower intensities of PA or between PA and FMD in those subjects who possess preserved vascular function a priori .

1. To examine the influence of the rate of heat loss on the magnitude of post-exercise hypotension, subjects were exposed to three different environmental conditions during recovery from bicycle exercise. 2. When subjects recovered in warm conditions both core temperature (measured in the external auditory meatus) and mean skin temperature were significantly elevated 60 min after the cessation of exercise. This attenuation of heat loss was associated with a significant reduction in post-exercise mean arterial pressure. 3. In contrast, when subjects recovered in neutral or cool conditions both core temperature and mean arterial pressure had returned to baseline levels 60 min after exercise. 4. These results indicate that persistence of peripheral vasodilatation during recovery from exercise, and therefore the magnitude of post-exercise hypotension, is dependent upon thermoregulatory-induced changes in skin blood flow.