Kade Davison

Impact of cocoa flavanol consumption on blood pressure responsiveness to exercise

Impaired endothelial vasodilatation may contribute to the exaggerated blood pressure (BP) responses to exercise in individuals who are overweight/obese. The present study investigated whether consumption of cocoa flavanols, which improve endothelium-dependent flow-mediated dilatation (FMD), can modify BP responsiveness to exercise. Twenty-one volunteers (eight females and thirteen males, 54.9 (se 2.2) years, BMI 31.6 (se 0.8) kg/m2, systolic BP 134 (se 2) mmHg, diastolic BP (DBP) 87 (se 2) mmHg) were randomised to consume single servings of either a high-flavanol (HF, 701 mg) or a low-flavanol (LF, 22 mg) cocoa beverage in a double-blind, cross-over design with 3-7-d washout between treatments. Two hours after cocoa consumption, FMD was measured, followed by continuous beat-to-beat assessment (Finapres) of BP before and during 10 min of cycling at 75 % of age-predicted maximum heart rate. Averaged data from two assessments on each type of beverage were compared by analysis of covariance using pre-exercise BP as the covariate. Pre-exercise BP was similar after taking LF and HF (153 (se 3)/88 (se 3) v. 153 (se 4)/87 (se 2) mmHg, respectively, P>0.05). However, the BP response to exercise (area under BP curve) was attenuated by HF compared with LF. BP increases were 68 % lower for DBP (P = 0.03) and 14 % lower for mean BP (P = 0.05). FMD measurements were higher after taking HF than after taking LF (6.1 (se 0.6) % v. 3.4 (se 0.5) %, P < 0.001). By facilitating vasodilation and attenuating exercise-induced increases in BP, cocoa flavanols may decrease cardiovascular risk and enhance the cardiovascular benefits of moderate intensity exercise in at-risk individuals.

Dose-related effects of flavanol-rich cocoa on blood pressure

Consumption of flavanol-containing cocoa products has been shown to lower blood pressure (BP), but the minimum dose required to reduce BP is not known. This study aimed to examine the effect of three different doses of cocoa flavanols (CF) on 24-h mean arterial BP. Twenty four hour ambulatory BP (24-ABP) monitoring was performed in 32 men and 20 postmenopausal women with untreated mild hypertension (seated clinic BP >130/85 and <160/100 mm Hg). Participants were randomized and instructed to consume daily a reconstituted cocoa beverage containing 33, 372, 712 or 1052 mg day−1 of CF for 6 weeks in a double-blind, parallel comparison. Seated clinic BP and 24-h ABP were measured at 0, 3 and 6 weeks. Seated clinic BP did not change during the study period. There were significant reductions in 24-h systolic (5.3±5.1 mm Hg; P=0.001), diastolic (3±3.2 mm Hg; P=0.002) and mean arterial BP (3.8±3.2 mm Hg; P=0.0004) at the 1052 mg day−1 CF only. No reduction in BP was seen at any other dose. No evidence of dose–response was seen in this experiment. The highest dose of 1052 mg CF per day was found to significantly lower BP. These results support previous evidence for CF to lower BP, however more research is needed to establish the most effective dose and food matrix.

Relationships between Obesity, Cardiorespiratory Fitness, and Cardiovascular Function

Background. Obesity and low cardiorespiratory fitness (CRF) have been shown to independently increase the risk of CVD mortality. The aim of this study was to investigate the relationship between CRF, body fatness and markers of arterial function. Method and Results. Obese (9 male, 18 female; BMI 35.3 ± 0.9 kg·m−2) and lean (8 male, 18 female; BMI 22.5 ± 0.3 kg·m−2) volunteers were assessed for body composition (DXA), cardiorespiratory fitness (predicted V˙O2max), blood pressure (BP), endothelial vasodilatator function (FMD), and arterial compliance (AC) (via radial artery tonometry). The obese group had more whole body fat and abdominal fat (43.5 ± 1.2% versus 27.2 ± 1.6%; P < .001 and 48.6 ± 0.9% versus 28.9 ± 1.8%; P < .001, resp.), and lower FMD (3.2 ± 0.4% versus 5.7 ± 0.7%; P < .01) than the lean subjects, but there was no difference in AC. AC in large arteries was positively associated with CRF (R = 0.5; P < .01) but not with fatness. Conclusion. These results indicate distinct influences of obesity and CRF on blood vessel health. FMD was impaired with obesity, which may contribute to arterial and metabolic dysfunction. Low CRF was associated with reduced elasticity in large arteries, which could result in augmentation of aortic afterload.

An evaluation of inertial sensor technology in the discrimination of human gait

Abstract Inertial sensors may provide the opportunity for broader and more cost effective gait analysis; however some questions remain over their potential use in this capacity. The aim of the study was to determine whether an inertial sensor could discriminate between normal walking, fast walking, and running. A single group crossover design was used to compare acceleration profiles between three gait conditions: normal walking, fast walking, and running. An inertial sensor was placed on the sacrum of 12 participants (6 male, 6 female) who performed 3 trials of each gait condition on both overground and treadmill settings. A significant difference (P < 0.001) in the occurrence of heel strike in the gait cycle was found between running and both walking conditions. No differences were seen between overground and treadmill in any condition or variable. The results indicate that a single sacral mounted inertial sensor can differentiate running from normal walking and fast walking using temporal gait event measures. This study indicates that inertial sensors can differentiate walking from running gait in healthy individuals which may have potential for application in the quantification of physical activity in the health and exercise industry.

Contextualizing Parasympathetic Hyperactivity in Functionally Overreached Athletes with Perceptions of Training Tolerance

PURPOSE Heart-rate variability (HRV) as a measure of autonomic function may increase in response to training interventions leading to increases or decreases in performance, making HRV interpretation difficult in isolation. This study aimed to contextualize changes in HRV with subjective measures of training tolerance. METHODS Supine and standing measures of vagally mediated HRV (root-mean-square difference of successive normal RR intervals [RMSSD]) and measures of training tolerance (Daily Analysis of Life Demands for Athletes questionnaire, perception of energy levels, fatigue, and muscle soreness) were recorded daily during 1 wk of light training (LT), 2 wk of heavy training (HT), and 10 d of tapering (T) in 15 male runners/ triathletes. HRV and training tolerance were analyzed as rolling 7-d averages at LT, HT, and T. Performance was assessed after LT, HT, and T with a 5-km treadmill time trial (5TTT). RESULTS Time to complete the 5TTT likely increased after HT (effect size [ES] ± 90% confidence interval = 0.16 ± 0.06) and then almost certainly decreased after T (ES = -0.34 ± 0.08). Training tolerance worsened after HT (ES ≥ 1.30 ± 0.41) and improved after T (ES ≥ 1.27 ± 0.49). Standing RMSSD very likely increased after HT (ES = 0.62 ± 0.26) and likely remained higher than LT at the completion of T (ES = 0.38 ± 0.21). Changes in supine RMSSD were possible or likely trivial. CONCLUSIONS Vagally mediated HRV during standing increased in response to functional overreaching (indicating potential parasympathetic hyperactivity) and also to improvements in performance. Thus, additional measures such as training tolerance are required to interpret changes in vagally mediated HRV.

Potential implications of dose and diet for the effects of cocoa flavanols on cardiometabolic function.

The metabolic syndrome is a pathological state whereby cardiovascular and metabolic dysfunction coexist and typically progress in a mutual feed-forward manner to further dysfunction and ultimately disease. The health and function of the vascular endothelium is integral in this phenomenon and thus represents a logical target for intervention. Consumption of foods high in cocoa flavanols has demonstrated a capacity to markedly improve endothelial function and key markers of the metabolic syndrome including blood pressure and insulin sensitivity. The typically high energy content of foods containing sufficient doses of cocoa flavanols has caused some reservations around its therapeutic use, but this is dependent upon the particulars of the food matrix used. Further to this, the food matrix appears to influence the dose response curve of cocoa flavanols, particularly on blood pressure, with dark chocolate appearing to be 8 times more effective in systolic blood pressure reduction than a cocoa powder drink for the equivalent dose of flavanol. Cocoa flavanol consumption conclusively demonstrates a positive impact on cardiometabolic function; however, more research is needed to understand how best to consume it to maximize the benefit while avoiding excessive fat and sugar consumption.

The Effect of Anthocyanin-Rich Foods or Extracts on Vascular Function in Adults: A Systematic Review and Meta-Analysis of Randomised Controlled Trials

Anthocyanins are of interest due to their anti-oxidative and vasodilatory properties. Earlier reviews have shown that berries and other anthocyanin rich foods or extracts can improve vascular health, however the effect of anthocyanins on vascular function has not yet been reviewed. To address this gap in the literature, we conducted a systematic review and meta-analysis of randomised-controlled trials examining anthocyanin-rich foods or extracts on measures of vascular reactivity and/or stiffness in adults. Data from 24 studies were pooled as standardized mean difference (SMD) with 95% confidence intervals (CI). Anthocyanin consumption significantly improved flow-mediated dilation (FMD) following acute (SMD: 3.92%, 95% CI: 1.47, 6.38, p = 0.002; I2 = 91.8%) and chronic supplementation (SMD: 0.84%, 95% CI: 0.55, 1.12, p = 0.000; I2 = 62.5%). Pulse wave velocity was improved following acute supplementation only (SMD: −1.27 m/s, 95% CI: −1.96, −0.58, p = 0.000; I2 = 17.8%). These results support the findings of previous reviews that anthocyanin rich foods or extracts may indeed improve vascular health, particularly with respect to vascular reactivity measured by FMD. More research is required to determine the optimal dosage, and the long-term effects of consumption.

Therapeutic effects of aerobic and resistance exercises for cancer survivors: a systematic review of meta-analyses of clinical trials

Objective To systematically appraise and summarise meta-analyses investigating the effect of exercise compared with a control condition on health outcomes in cancer survivors. Design Umbrella review of intervention systematic reviews. Data sources Web of Science, Scopus, Cochrane Library, CINAHL and MEDLINE databases were searched using a predefined search strategy. Eligibility criteria Eligible meta-analyses compared health outcomes between cancer survivors participating in an exercise intervention and a control condition. Health outcomes were cardiovascular fitness, muscle strength, health-related quality of life, cancer-related fatigue and depression. Pooled effect estimates from each meta-analysis were quantified using standardised mean differences and considered trivial (<0.20), small (0.20–0.49), moderate (0.50–0.79) and large (≥0.80). Findings were summarised using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system. Results There were 65 eligible articles that reported a total of 140 independent meta-analyses. 139/140 meta-analyses suggested a beneficial effect of exercise. The beneficial effect was statistically significant in 104 (75%) meta-analyses. Most effect sizes were moderate for cardiovascular fitness and muscle strength and small for cancer-related fatigue, health-related quality of life and depression. The quality of evidence was variable according to the GRADE scale, with most studies rated low or moderate quality. Median incidence of exercise-related adverse events was 3.5%. Conclusion Exercise likely has an important role in helping to manage physical function, mental health, general well-being and quality of life in people undergoing and recovering from cancer and side effects of treatment. PROSPERO registration number CRD42015020194.

Exercise prescription is not just for medical doctors: the benefits of shared care by physicians and exercise professionals

As allied health professionals, we commend the Canadian Academy of Sport and Exercise Medicine (CASEM) on their recent position statement to better equip physicians for physical activity prescription.1 The CAESM call on physicians to be more engaged in physical activity prescription to reduce the burden of non-communicable diseases associated with physical inactivity. Physicians are uniquely positioned in healthcare systems to improve population levels of physical activity. Most people visit a physician at least annually, and physician advice remains influential in guiding patient behaviour. For example, a simple physical activity counselling intervention by general practitioners significantly reduced inactivity.2 A key objective of the Exercise is Medicine initiative http://www.exerciseismedicine.org/ is for physicians to assess and record physical activity during every patient visit, similar to a vital sign and to facilitate an exercise prescription. However, despite the acknowledged intentions of the CAESM statement, many physicians will remain ill-equipped, or simply not have time, to deliver individualised exercise prescriptions to patients across the …

Impact of Cocoa Flavanols on Cardiovascular Health: Additional Consideration of Dose and Food Matrix.

Dear editor, We read with interest the recent article by Vlachojannis and colleagues in which they summarised reviews of the effects of cocoa derived flavanols on cardiovascular function (Vlachojannis et al., 2016). We agree that there is a lack of consistency in findings, particularly in relation to blood pressure (BP), and that better reporting of flavanol content in research reports and on consumer products is needed. There are three aspects of their paper that we feel warrant further discussion.