The impact of obesity on cardiac troponin levels after prolonged exercise in humans

Elevated cardiac troponin I (cTnI), a marker for cardiac damage, has been reported after high-intensity exercise in healthy subjects. Currently, little is known about the impact of prolonged moderate-intensity exercise on cTnI release, but also the impact of obesity on this response. 97 volunteers (55 men and 42 women), stratified for BMI, performed a single bout of walking exercise (30–50 km). We examined cTnI-levels before and immediately after the exercise bout in lean (BMI < 25 kg/m2, n = 30, 57 ± 19 years), overweight (25 ≤ BMI < 30 kg/m2, n = 29, 56 ± 11 years), and obese subjects (BMI ≥ 30 kg/m2, n = 28, 53 ± 9 years). Walking was performed at a self-selected pace. cTnI was assessed using a high-sensitive cTnI-assay (Centaur; clinical cut-off value ≥0.04 μg/L). We recorded subject characteristics (body weight, blood pressure, presence of cardiovascular risk) and examined exercise intensity by recording heart rate. Mean cTnI-levels increased significantly from 0.010 ± 0.006 to 0.024 ± 0.046 μg/L (P < 0.001). The exercise-induced increase in cTnI was not different between lean, overweight and obese subjects (two-way ANOVA interaction; P = 0.27). In 11 participants, cTnI was elevated above the clinical cut-off value for myocardial infarction. Logistic regression analysis identified exercise intensity (P < 0.001), but not BMI, body fat percentage or waist circumference to significantly relate to positive troponin tests. In conclusion, prolonged, moderate-intensity exercise results in a comparable increase in cTnI-levels in lean, overweight and obese subjects. Therefore, measures of obesity unlikely relate to the magnitude of the post-exercise elevation in cTnI

A Systematic Review with Meta-Analysis of Randomized Controlled Trials

Objective Epidemiological evidence has linked consumption of black tea, produced from Camellia sinensis, with a reduced risk of cardiovascular diseases. However, intervention studies on the effects of tea consumption on blood pressure (BP) have reported inconsistent results. Our objective was to conduct a systematic literature review with meta-analysis of controlled human intervention studies examining the effect of tea consumption on BP. Methods We systematically searched Medline, Biosis, Chemical Abstracts and EMBASE databases through July 2013. For inclusion, studies had to meet the following pre-defined criteria: 1) placebo controlled design in human adults, 2) minimum of 1 week black tea consumption as the sole intervention, 3) reported effects on systolic BP (SBP) or diastolic BP (DBP) or both. A random effects model was used to calculate the pooled overall effect of black tea on BP. Results Eleven studies (12 intervention arms, 378 subjects, dose of 4–5 cups of tea) met our inclusion criteria. The pooled mean effect of regular tea ingestion was −1.8 mmHg (95% CI: −2.8, −0.7; P = 0.0013) for SBP and −1.3 mmHg (95% CI: −1.8, −0.8; P<0.0001) for DBP. In covariate analyses, we found that the method of tea preparation (tea extract powders versus leaf tea), baseline SBP and DBP, and the quality score of the study affected the effect size of the tea intervention (all P<0.05). No evidence of publication bias could be detected. Conclusions Our meta-analysis indicates that regular consumption of black tea can reduce BP. Although the effect is small, such effects could be important for cardiovascular health at population level

Fluctuation in Shear Rate, with Unaltered Mean Shear Rate, Improves Brachial Artery Flow-Mediated Dilation in Healthy, Young Men.

AIM: Increase in mean shear stress represents an important and potent hemodynamic stimulus to improve conduit artery endothelial function in humans. No previous study has examined whether fluctuations in shear rate patterns, without altering mean shear stress, impacts conduit artery endothelial function. This study examined the hypothesis that 30-minutes exposure to fluctuations in shear rate patterns, in the presence of unaltered mean shear rate, improves brachial artery flow-mediated dilation. METHODS: Fifteen healthy males (27.3±5.0 years) completed the study. Bilateral brachial artery flow-mediated dilation was assessed before and after unilateral exposure to 30-minutes of intermittent negative pressure (10seconds -40mmHg, 7seconds 0mmHg) to induce fluctuation in shear rate, whilst the contra-lateral arm was exposed to a resting period. RESULTS: Negative pressure significantly increased shear rate, followed by a decrease in shear rate upon pressure release (both P<0.001). Across the 30-minute intervention, mean shear rate was not different compared to baseline (P=0.458). A linear mixed model revealed a significant effect of time was observed for flow-mediated dilation (P=0.029), with exploratory post-hoc analysis showing an increase in the intervention arm (∆FMD +2.0%, P=0.008), but not in the contra-lateral control arm (∆FMD +0.5%, P=0.664). However, there was no effect for arm (P=0.619) or interaction effect (P=0.096). CONCLUSION: In conclusion, we found that fluctuations in shear patterns, with unaltered mean shear, improves brachial artery flow-mediated dilation. These novel data suggest that fluctuations in shear pattern, even in the absence of altered mean shear, represents a stimulus to acute change in endothelial function in healthy individuals

Vascular Function and Structure in Veteran Athletes after Myocardial Infarction.

PURPOSE: Although athletes demonstrate lower cardiovascular risk and superior vascular function compared with sedentary peers, they are not exempted from cardiac events (i.e., myocardial infarction [MI]). The presence of an MI is associated with increased cardiovascular risk and impaired vascular function. We tested the hypothesis that lifelong exercise training in post-MI athletes, similar as in healthy controls, is associated with a superior peripheral vascular function and structure compared with a sedentary lifestyle in post-MI individuals. METHODS: We included 18 veteran athletes (ATH) (>20 yr) and 18 sedentary controls (SED). To understand the effect of lifelong exercise training after MI, we included 20 veteran post-MI athletes (ATH + MI) and 19 sedentary post-MI controls (SED + MI). Participants underwent comprehensive assessment using vascular ultrasound (vascular stiffness, intima-media thickness, and endothelium (in)dependent mediated dilatation). Lifetime risk score was calculated for a 30-yr risk prediction of cardiovascular disease mortality of the participants. RESULTS: ATH demonstrated a lower vascular stiffness and smaller femoral intima-media thickness compared with SED. Vascular function and structure did not differ between ATH + MI and SED + MI. ATH (4.0% ± 5.1%) and ATH + MI (6.1% ± 3.7%) had a significantly better lifetime risk score compared with their sedentary peers (SED: 6.9% ± 3.7% and SED + MI: 9.3% ± 4.8%). ATH + MI had no secondary events versus two recurrent MI and six elective percutaneous coronary interventions within SED + MI (P < 0.05). CONCLUSION: Although veteran post-MI athletes did not have a superior peripheral vascular function and structure compared with their sedentary post-MI peers, benefits of lifelong exercise training in veteran post-MI athletes relate to a better cardiovascular risk profile and lower occurrence of secondary events

The impact of 24 weeks of supervised endurance versus resistance exercise training on left ventricular mechanics in healthy untrained humans.

BACKGROUND: In addition to the well-known cardiac structural adaptation to exercise training, little work examined changes in LV mechanics. With new regional and global indices available we sought to determine the effect of 24 weeks endurance versus resistance training on LV mechanics. METHODS AND RESULTS: 23 male subjects were randomly allocated to either a 24-week endurance- or resistance-training program. Pre- and post-training 2D echocardiographic images were acquired. Global LV mechanics (strain [ε]) were recorded in longitudinal, circumferential and radial planes. Rotation was assessed at apical and basal levels. In addition, longitudinal ε-volume loops, across the cardiac cycle, were constructed from simultaneous LV ε (longitudinal and transverse strain) and volume measurements across the cardiac cycle as a novel measure of LV mechanics. Marginal differences in ε and rotation data were found between groups. Post-training, we found no change in global peak ε data. Peak basal rotation significantly increased after training with changes in the endurance group (-2.2±1.9o to -4.5±3.3o) and the resistance group (-2.9±3.0o to -3.4±2.9o) . LV ε-volume loops revealed a modest rightward shift in both groups. CONCLUSIONS: Whilst most global and regional indices of LV mechanics were not significantly altered, 24 weeks of intense supervised exercise training increased basal rotation. Further studies that assess LV mechanics in larger cohorts of subjects and those with cardiovascular disease and risk factors may reveal important training impacts

Adherence to guidelines strongly improves reproducibility of brachial artery flow-mediated dilation.

BACKGROUND: Brachial artery FMD is widely used as a non-invasive measure of endothelial function. Adherence to expert guidelines is believed to be of vital importance to obtain reproducible measurements. We conducted a systematic review of studies reporting on the reproducibility of the FMD in order to determine the relation between adherence to current expert guidelines for FMD measurement and its reproducibility. METHODS: Medline-database was searched through July 2015 and 458 records were screened for FMD reproducibility studies reporting the mean difference and variance of repeated FMD measurements. An adherence score was assigned to each of the included studies based on reported adherence to published guidelines on the assessment of brachial artery FMD. A Typical Error Estimate (TEE) of the FMD was calculated for each included study. The relation between the FMD TEE and the adherence score was investigated by means of Pearson correlation coefficients and multiple linear regression analysis. RESULTS: Twenty-seven studies involving 48 study groups and 1537 subjects were included in the analyses. The adherence score ranged from 2.4 to 9.2 (out of a maximum of 10) and was strongly and inversely correlated with FMD TEE (adjusted R(2) = 0.36, P < 0.01). Use of automated edge-detection software, continuous diameter measurement, true peak diameter for %FMD calculation, a stereostatic probe holder, and higher age emerged as factors associated with a lower FMD TEE. CONCLUSIONS: These data demonstrate that adherence to current expert consensus guidelines and applying contemporary techniques for measuring brachial artery FMD decreases its measurement error

Randomized controlled trial using bosentan to enhance the impact of exercise training in subjects with type 2 diabetes mellitus

In type 2 diabetes patients, endothelin (ET) receptor blockade may enhance blood flow responses to exercise training. The combination of exercise training and ET receptor blockade may represent a more potent stimulus than training alone to improve vascular function, physical fitness and glucose homeostasis. We assessed the effect of an 8 week exercise training programme combined with either ET blockade or placebo on vasculature, fitness and glucose homeostasis in people with type 2 diabetes. In a double-blind randomized controlled trial, brachial endothelium-dependent and -independent dilatation (using flow-mediated dilatation and glyceryl trinitrate, respectively), glucose homeostasis (using Homeostasis Model Assessment for Insulin Resistance (HOMA-IR)) and physical fitness (maximal cycling test) were assessed in 18 men with type 2 diabetes (60 ± 6 years old). Subjects underwent an 8 week exercise training programme, with half of the subjects receiving ET receptor blockade (bosentan) and the other half a placebo, followed by reassessment of the tests above. Exercise training improved physical fitness to a similar extent in both groups, but we did not detect changes in vascular function in either group. This study suggests that there is no adaptation in brachial and femoral artery endothelial function after 8 weeks of training in type 2 diabetes patients. Endothelin receptor blockade combined with exercise training does not additionally alter conduit artery endothelial function or physical fitness in type 2 diabetes

Heart failure patients demonstrate impaired changes in brachial artery blood flow and shear rate pattern during moderate-intensity cycle exercise

New Findings What is the central question of this study? We explored whether heart failure (HF) patients demonstrate different exercise-induced brachial artery shear rate patterns compared with control subjects. What is the main finding and its importance? Moderate-intensity cycle exercise in HF patients is associated with an attenuated increase in brachial artery anterograde and mean shear rate and skin temperature. Differences between HF patients and control subjects cannot be explained fully by differences in workload. HF patients demonstrate a less favourable shear rate pattern during cycle exercise compared with control subjects. Repeated elevations in shear rate (SR) in conduit arteries, which occur during exercise, represent a key stimulus to improve vascular function. We explored whether heart failure (HF) patients demonstrate distinct changes in SR in response to moderate-intensity cycle exercise compared with healthy control subjects. We examined brachial artery SR during 40 min of cycle exercise at a work rate equivalent to 65% peak oxygen uptake in 14 HF patients (65 ± 7 years old, 13 men and one woman) and 14 control subjects (61 ± 5 years old, 12 men and two women). Brachial artery diameter, SR and oscillatory shear index (OSI) were assessed using ultrasound at baseline and during exercise. The HF patients demonstrated an attenuated increase in mean and anterograde brachial artery SR during exercise compared with control subjects (time × group interaction, P = 0.003 and P 0.05). In conclusion, HF patients demonstrate a less favourable SR pattern during cycle exercise than control subjects, characterized by an attenuated mean and anterograde SR and by increased OSI

Combined aerobic and resistance exercise training decreases peripheral but not central artery wall thickness in subjects with type 2 diabetes

Objective Little is known about the impact of exercise training on conduit artery wall thickness in type 2 diabetes. We examined the local and systemic impact of exercise training on superficial femoral (SFA), brachial (BA), and carotid artery (CA) wall thickness in type 2 diabetes patients and controls. Methods Twenty patients with type 2 diabetes and 10 age- and sex-matched controls performed an 8-week training study involving lower limb-based combined aerobic and resistance exercise training. We examined the SFA to study the local effect of exercise, and also the systemic impact of lower limb-based exercise training on peripheral (i.e. BA) and central (i.e. CA) arteries. Wall thickness (WT), diameter and wall:lumen(W:L)-ratios were examined using automated edge detection of ultrasound images. Results Exercise training did not alter SFA or CA diameter in type 2 diabetes or controls (all P > 0.05). BA diameter was increased after training in type 2 diabetes, but not in controls. Exercise training decreased WT and W:L ratio in the SFA and BA, but not in CA in type 2 diabetes. Training did not alter WT or W:L ratio in controls (P > 0.05). Conclusion Lower limb-dominant exercise training causes remodelling of peripheral arteries, supplying active and inactive vascular beds, but not central arteries in type 2 diabetes

Impact of lifelong exercise training on endothelial ischemia-reperfusion and ischemic preconditioning in humans.

Reperfusion is essential for ischemic tissue survival, but causes additional damage to the endothelium (i.e. ischemia-reperfusion [IR] injury). Ischemic preconditioning (IPC) refers to short repetitive episodes of ischemia that can protect against IR. However, IPC efficacy attenuates with older age. Whether physical inactivity contributes to the attenuated efficacy of IPC to protect against IR injury in older humans is unclear. We tested the hypotheses that lifelong exercise training relates to 1) attenuated endothelial IR and 2) maintained IPC efficacy that protects veteran athletes against endothelial IR. In 18 sedentary male individuals (SED, 20 years, 63±7 years) and 20 veteran male athletes (ATH, >5 exercise hours/week for >20 years, 63±6 years), we measured brachial artery endothelial function with flow-mediated dilation (FMD) before and after IR. We induced IR by 20-minutes of ischemia followed by 20-minutes of reperfusion. Randomized over 2 days, participants underwent either 35-minute rest or IPC (3 cycles of 5-minutes cuff inflation to 220 mmHg with 5-minutes of rest) before IR. In SED, FMD decreased after IR (median [interquartile range]): (3.0% [2.0-4.7] to 2.1% [1.5-3.9], P=0.046) and IPC did not prevent this decline (4.1% [2.6-5.2] to 2.8% [2.2-3.6],P=0.012). In ATH, FMD was preserved after IR (3.0% [1.7-5.4] to 3.0% [1.9-4.1], P=0.82) and when IPC preceded IR (3.2% [1.9-4.2] to 2.8% [1.4-4.6],P=0.18). These findings indicate that lifelong exercise training is associated with increased tolerance against endothelial IR. These protective, preconditioning effects of lifelong exercise against endothelial ischemia-reperfusion may contribute to the cardio-protective effects of exercise training