Do Aerobic Exercise and Mindfulness Act Synergistically to Mitigate Psychological Distress in College Students Experiencing High Levels of Stress?

Purpose: To assess whether there is a synergistic beneficial effect of aerobic exercise (AE) and mindfulness meditation (MM), compared to effects of MM alone, on stress and related variables in high-stress young adults. Methods: 32 high-stress young adults were randomized to a four-week MM, AE+MM, or control intervention. Perceived stress (PSSQ), and anxiety/depression (DASSQ) were assessed at baseline, and after weeks 1 and 4. A randomized sub-sample from each group underwent physiological testing at baseline and post-intervention. Results: No significant interactions were found (PSS: p=0.12; DASS: p=0.21; heart rate: p=0.50; systolic blood pressure: p=0.90; diastolic blood pressure: p=0.16; arterial stiffness: p=0.90; heart rate variability: p=0.53). PSS and DASS decreased from baseline to post in MM (PSS: ↓27%; DASS: ↓43%) and AE+MM (PSS: ↓34%; DASS: ↓40%). Little change occurred in Control (PSS: ↓8%; DASS: ↓ 4%). Conclusion: MM may be as effective as AE+MM in combatting psychological distress in young adults.Master of Art

THE EFFECTS OF A PRIOR EXERCISE BOUT ON THE ENERGETIC AND CARDIOMETABOLIC RESPONSES TO ACUTE MENTAL STRESS

Background: Mental stress is associated with cardiovascular disease (CVD) risk, but the arterial stiffness and energy expenditure (EE) responses to acute mental stress, and whether prior exercise impacts post-stress cardiometabolic reactivity are not known. The objectives of this dissertation were to assess arterial stiffness and EE responses to acute mental stress and to determine the impact of a prior exercise bout on these responses. Methods: In addition to a meta-analysis on the effects of acute mental stress on arterial stiffness, this dissertation entailed two randomized cross-over studies. Forty recreationally active young adults (18-30 y) were recruited. For Cross-over 1, 20 participants attended two laboratory visits: i) Trier Social Stress Test (arithmetic + speech), and ii) Control. For Cross-over 2, 20 different participants attended two laboratory visits: i) Exercise + Trier Social Stress Test (psychosocial task), and ii) Exercise + Control. Exercise consisted of 25 minutes of moderate-intensity elliptical. Arterial stiffness and EE were measured by pulse-wave velocity (PWV) and indirect calorimetry, respectively. Measurements took place pre, during (EE only), and post condition. Mixed model linear regression assessed condition x time interactions. Results: Meta-analysis: Across 17 trials from 9 studies, exposure to acute mental stress caused arterial stiffness to increase (Standardized Mean Difference: 0.45; p<0.05). Cross-over 1: There was a small interaction (B=0.68 m/s, 95%CI: 0.39, 0.97) for PWV [Stress: 0.81 m/s, Control: 0.15 m/s]. There was also a small interaction (B=0.0010 kcal/kg/min, 95%CI: 0.0004, 0.0015) for EE (Stress: 0.0016 kcal/kg/min, Control:0.0005 kcal/kg/min). Cross-over 2: There was a small interaction (B=0.47 m/s, 95%CI: 0.21, 0.72) for PWV (Stress: 0.43 m/s, Control: -0.05 m/s). For EE, there were small main effects of condition (B=0.0005 kcal/kg/min), 95%CI: 0.0003, 0.0008) and time (B=0.0011 kcal/kg/min, 95%CI: 0.0006, 0.0016). Compared to Cross-over 1, the prior exercise introduced in Cross-over 2 dampened the arterial stiffness and EE responses. Conclusions: Arterial stiffness and EE may be key players in the relationship between acute mental stress and CVD risk, and exercise may beneficially moderate this relationship. Future research examining the stress-CVD paradigm, including potential protective effects of exercise, will be necessary to inform stress-related CVD prevention and treatment efforts.Doctor of Philosoph

The aortic-femoral arterial stiffness gradient demonstrates good between-day reliability

In a healthy cardiovascular system, arterial stiffness progressively increases from the elastic aorta to the muscular conduit arteries of the periphery. This stiffness gradient permits a gradual attenuation of the forward pressure wave into a smooth consistent blood flow and prevents the transmission of pulsatile forces to the microcirculation and endorgans [1]. However, aging and lifestyle factors may disrupt these beneficial phenomena [2]. In particular, the aorta tends to stiffen, whereas changes in lower-limb arterial stiffness, for example, are less marked [2]. These differential changes in stiffness lead to a reversal of the stiffness gradient, increasing forward pressure transmission, and contributing to end-organ damage [1, 3]. A recent study reported that the stiffness gradient between aortic and lower-limb arterial stiffness provided prognostic information beyond the carotid-femoral pulse-wave velocity (cfPWV), a criterion measure of arterial health [4]. This measure provides a promising opportunity to gain meaningful insight into the hemodynamic integration of the vascular system. However, a measurement must have acceptable precision (reliability) to be of value in clinical and research settings. Therefore, the objective of this study was to estimate the between-day reliability of the aortic-femoral arterial stiffness gradient (af-SG)

Leg Fidgeting Improves Executive Function following Prolonged Sitting with a Typical Western Meal: A Randomized, Controlled Cross-Over Trial.

Prolonged uninterrupted sitting and a typical Western meal, high in fat and refined sugar, can additively impair cognitive and cerebrovascular functions. However, it is unknown whether interrupting these behaviours, with a simple desk-based activity, can attenuate the impairment. The aim of this study was to determine whether regular leg fidgeting can off-set the detrimental effects of prolonged sitting following the consumption of a typical Western meal, on executive and cerebrovascular function. Using a randomized cross-over design, 13 healthy males consumed a Western meal and completed 180-min of prolonged sitting with leg fidgeting of 1 min on/4 min off (intervention [INT]) and without (control [CON]). Cognitive function was assessed pre and post sitting using the Trail Maker Test (TMT) parts A and B. Common carotid artery (CCA) blood flow, as an index of brain flow, was measured pre and post, and cerebral (FP1) perfusion was measured continuously. For TMT B the CON trial signifi-cantly increased (worsened) completion time (mean difference [MD]=5.2s, d= 0.38), the number of errors (MD=3.33, d= 0.68) and cognitive fatigue (MD=0.73, d= 0.92). Compared to CON, the INT trial significantly improved completion time (MD=2.3s, d= 0.97), and prevented declines in cognitive fatigue and a reduction in the number of errors. No significant changes in cerebral perfusion or CCA blood flow were found. Leg fidgeting for 1-min on/4-min off following a meal high in fats and refined sugars attenuated the impairment in executive function. This attenuation in executive function may not be caused by al-terations in CCA blood flow or cerebral perfusion

Central and peripheral arterial stiffness responses to uninterrupted prolonged sitting combined with a high-fat meal: a randomized, controlled cross-over trial

Background and aims: Independently, prolonged uninterrupted sitting and the consumption of a meal high in saturated fats acutely disrupt normal cardiovascular function. Currently the acute effects of these behaviours performed in combination on arterial stiffness, a marker of cardiovascular health, is unknown. This study sought to determine the effect of consuming a high-fat meal (Δ= 51 g fat) in conjunction with prolonged uninterrupted sitting (180 min) on measures of central and peripheral arterial stiffness. Methods: Using a randomized crossover design, thirteen young healthy males consumed a high-fat (61 g) or low-fat (10 g) meal before 180 min of uninterrupted sitting. Carotid-femoral (cf-) and femoral-ankle (fa-) pulse wave velocity (PWV), aortic-femoral stiffness gradient (af-SG), superficial femoral PWV beta (β), and oscillometric pulse wave analysis outcomes were assessed pre and post sitting. Results: cfPWV increased significantly more following the high-fat (mean difference [MD]= 0.59 m·s-1) when compared to the low-fat (MD= 0.2 m·s-1) meal, with no change in faPWV in either condition. The af-SG significantly decreased (worsened) (ηp2= 0.569) overtime in high and low-fat conditions (ratio= 0.1 and 0.1 respectively). Superficial femoral PWVβ significantly increased over time in high- and low-fat conditions (ηp2= 0.321; 0.8 and 0.4 m·s-1 respectively). A significant interaction found that triglycerides increased over time in the high fat trial only (ηp2= 0.761). There were no significant changes in blood pressures. Conclusions: Consuming a high-fat meal prior to 180 min of uninterrupted sitting augments markers of cardiovascular disease risk more than sitting following a low-fat meal

Acute changes in carotid-femoral pulse-wave velocity are tracked by heart-femoral-pulse-wave velocity

Background: Carotid-femoral pulse-wave velocity (cfPWV) is the reference standard measure of central arterial stiffness. However, it requires assessment of the carotid artery, which is technically challenging, and subject-level factors, including carotid artery plaque, may confound measurements. A promising alternative that overcomes these limitations is heart-femoral PWV (hfPWV), but it is not known to what extent changes in cfPWV and hfPWV are associated. Objectives: To determine, (1) the strength of the association between hfPWV and cfPWV; and (2) whether change in hfPWV is associated with change in cfPWV when central arterial stiffness is perturbed. Methods: Twenty young, healthy adults (24.0 [SD: 3.1] years, 45% female) were recruited. hfPWV and cfPWV were determined using Doppler ultrasound at baseline and following a mechanical perturbation in arterial stiffness (120mmHg thigh occlusion). Agreement between the two measurements was determined using mixed-effects regression models and Bland-Altman analysis. Results: There was, (1) strong (ICC >0.7) agreement between hfPWV and cfPWV (ICC= 0.82, 95%CI: 0.69,0.90), and, (2) very strong (ICC >0.9) agreement between change in hfPWV and cfPWV (ICC = 0.92, 95%CI: 0.86,0.96). cfPWV was significantly greater than hfPWV at baseline and during thigh occlusion (both P <0.001). Inspection of the Bland-Altman plot, comparing cfPWV and corrected hfPWV, revealed no measurement magnitude bias. Discussion: The current findings indicate that hfPWV and cfPWV are strongly associated, and that change in cfPWV is very strongly associated with change in hfPWV. hfPWV may be a simple alternative to cfPWV in the identification of cardiovascular risk in clinical and epidemiological settings

Cardiovascular consequences of skeletal muscle impairments in breast cancer

Breast cancer survivors suffer from disproportionate cardiovascular disease risk compared to age-matched controls. Beyond direct cardiotoxic effects due to treatments such as chemotherapy and radiation, breast-cancer-related reductions in skeletal muscle mass, quality and oxidative capacity may further contribute to cardiovascular disease risk in this population by limiting the ability to engage in aerobic exercise—a known promoter of cardiovascular health. Indeed, 20%–30% decreases in peak oxygen consumption are commonly observed in breast cancer survivors, which are indicative of exercise intolerance. Thus, breast-cancer-related skeletal muscle damage may reduce exercise-based opportunities for cardiovascular disease risk reduction. Resistance training is a potential strategy to improve skeletal muscle health in this population, which in turn may enhance the capacity to engage in aerobic exercise and reduce cardiovascular disease risk

Associations of lower-limb atherosclerosis and arteriosclerosis with cardiovascular risk factors and disease in older adults:The Atherosclerosis Risk in Communities (ARIC) study

BACKGROUND & AIMS Atherosclerosis and arteriosclerosis contribute to vascular aging and cardiovascular disease (CVD) risk. Both processes can be assessed simply in the lower-limbs and reflect systemic pathology. However, only atherosclerosis is routinely assessed, typically via ankle-brachial index (ABI). Arteriosclerosis can be assessed using femoral-ankle pulse wave velocity (faPWV), but no studies have identified whether ABI and faPWV similarly associate with overt CVD and risk factors, nor whether faPWV confers additional information. The aims of this study were to, (i) Compare associations of ABI and faPWV with traditional CVD risk factors, including age, sex, systolic blood pressure (SBP), high-density lipoprotein (HDL), total cholesterol (TC), smoking, and diabetes; and, ii) Determine the independent and additive associations of ABI and faPWV with a composite measure of prevalent CVD. METHODS We evaluated ABI and faPWV in 4,330 older-aged (75.3±5.0 years) adults using an oscillometric screening device. Associations between ABI and faPWV with CVD risk factors and CVD were determined using mixed-model linear- and logistic-regression. RESULTS ABI and faPWV were associated with age, HDL, and smoking. ABI was associated with sex, TC, diabetes. faPWV was associated with SBP. Both ABI and faPWV were inversely associated with CVD. Low ABI (≤0.9 vs. >0.9) and low faPWV (≤9.94 vs. >9.94) increased the odds of CVD by 2.41-fold (95% CI:1.85,3.17) and 1.46-fold (95% CI:1.23,1.74), respectively. The inverse association between faPWV and CVD was independent of ABI and CVD risk factors. CONCLUSION ABI and faPWV, measures of lower-limb atherosclerosis and arteriosclerosis, are independently associated with CVD risk factors and prevalent CVD. Assessment of faPWV may confer additional risk information beyond ABI

The pressure-dependency of local measures of arterial stiffness

Objective: To determine which ultrasound-based, single-point arterial stiffness estimate is least dependent on blood pressure to improve assessment of local vascular function. Methods: Ultrasound was used to assess blood flow and diameters at the left brachial artery of twenty healthy adults [55% F, 27.9 y (5.2), 24.2 (2.8) kg/m2]. Blood pressure of both arms was measured simultaneously. Experimental (left) arm blood pressure was then systematically manipulated by adjusting its position ABOVE (+30) and BELOW (-30) heart level in a randomized order following measurement at heart level (0). The control (right) arm remained at heart level. Six stiffness measurements were calculated: compliance, distensibility, beta-stiffness, and three estimates of pulse wave velocity (Bramwell Hill, blood flow, and Beta-stiffness). We considered the measurement technique with the least significant change across positions to be the least pressure-dependent. Results: There was a large effect change in mean arterial pressure (n2p = 0.75, p < 0.001) in the experimental arm when it was ABOVE (∆-4.4 mmHg) and BELOW (∆10.4 mmHg) heart level. There was a main effect (p < 0.05) of arm position on all arterial stiffness measures. From least to most pressure-dependent, the arterial stiffness measurements were: pulse wave velocity (blood flow method), compliance coefficient, beta-stiffness, distensibility coefficient, pulse wave velocity (Bramwell-Hill method), and pulse wave velocity (beta-stiffness index method). Conclusions: All single-point measures assessed are pressure-dependent. The pulse wave velocity (blood flow method) may be the least pressure-dependent single-point measure, and may be the most suitable single-point measure to assess local vascular function

The Aortic-Femoral Arterial Stiffness Gradient: An Atherosclerosis Risk in Communities (ARIC) Study

Background: The aortic to femoral arterial stiffness gradient (af-SG) may be a novel measure of arterial health and cardiovascular disease (CVD) risk, but its association with CVD risk factors and CVD status, and whether or not they differ from the referent measure, carotid-femoral pulse-wave velocity (cfPWV), is not known. Method: Accordingly, we compared the associations of the af-SG and cfPWV with (i) age and traditional CVD risk factors and (ii) CVD status. We evaluated 4183 older-aged (75.2 ± 5.0 years) men and women in the community-based Atherosclerosis Risk in Communities (ARIC) Study. cfPWV and femoral-ankle PWV (faPWV) were measured using an automated cardiovascular screening device. The af-SG was calculated as faPWV divided by cfPWV. Associations of af-SG and cfPWV with age, CVD risk factors (age, BMI, blood pressure, heart rate, glucose and blood lipid levels) and CVD status (hypertension, diabetes, coronary heart disease, heart failure, stroke) were determined using linear and logistic regression analyses. Results: (i) the af-SG and cfPWV demonstrated comparable associations with age and CVD risk factors, except BMI. (ii) a low af-SG was associated with diabetes, coronary heart disease, heart failure and stroke, whilst a high cfPWV was only associated with diabetes. Conclusion: Although future studies are necessary to confirm clinical utility, the af-SG is a promising tool that may provide a unique picture of hemodynamic integration and identification of CVD risk when compared with cfPWV