Temporal dynamics of sitting behavior at work.

Sitting for prolonged periods of time impairs people's health. Prior research has mainly investigated sitting behavior on an aggregate level, for example, by analyzing total sitting time per day. By contrast, taking a dynamic approach, here we conceptualize sitting behavior as a continuous chain of sit-to-stand and stand-to-sit transitions. We use multilevel time-to-event analysis to analyze the timing of these transitions. We analyze ∼30,000 objectively measured posture transitions from 156 people during work time. Results indicate that the temporal dynamics of sit-to-stand transitions differ from stand-to-sit transitions, and that people are quicker to switch postures later in the workday, and quicker to stand up after having been more active in the recent hours. We found no evidence for associations with physical fitness. Altogether, these findings provide insights into the origins of people's stand-up and sit-down decisions, show that sitting behavior is fundamentally different from exercise behavior, and provide pointers for the development of interventions.

The impact of age, sex, cardio-respiratory fitness, and cardiovascular disease risk on dynamic cerebral autoregulation and baroreflex sensitivity.

BACKGROUND: Humans display an age-related decline in cerebral blood flow and increase in blood pressure (BP), but changes in the underlying control mechanisms across the lifespan are less well understood. We aimed to; (1) examine the impact of age, sex, cardiovascular disease (CVD) risk, and cardio-respiratory fitness on dynamic cerebral autoregulation and cardiac baroreflex sensitivity, and (2) explore the relationships between dynamic cerebral autoregulation (dCA) and cardiac baroreflex sensitivity (cBRS). METHODS: 206 participants aged 18-70 years were stratified into age categories. Cerebral blood flow velocity was measured using transcranial Doppler ultrasound. Repeated squat-stand manoeuvres were performed (0.10 Hz), and transfer function analysis was used to assess dCA and cBRS. Multivariable linear regression was used to examine the influence of age, sex, CVD risk, and cardio-respiratory fitness on dCA and cBRS. Linear models determined the relationship between dCA and cBRS. RESULTS: Age, sex, CVD risk, and cardio-respiratory fitness did not impact dCA normalised gain, phase, or coherence with minimal change in all models (P > 0.05). cBRS gain was attenuated with age when adjusted for sex and CVD risk (young-older; ß = - 2.86 P < 0.001) along with cBRS phase (young-older; ß = - 0.44, P < 0.001). There was no correlation between dCA normalised gain and phase with either parameter of cBRS. CONCLUSION: Ageing was associated with a decreased cBRS, but dCA appears to remain unchanged. Additionally, our data suggest that sex, CVD risk, and cardio-respiratory fitness have little effect.

Diagnostic Accuracy of Monitoring Tests of Fellow Eyes in Patients with Unilateral Neovascular Age-Related Macular Degeneration: Early Detection of Neovascular Age-Related Macular Degeneration Study.

PURPOSE: To evaluate the diagnostic accuracy of routinely used tests of visual function and retinal morphology compared with fundus fluorescein angiography (FFA) to detect onset of active macular neovascularization in unaffected fellow eyes of patients with unilateral neovascular age-related macular degeneration (nAMD). DESIGN: Prospective diagnostic accuracy cohort study conducted in 24 eye clinics in the United Kingdom over 3 years. PARTICIPANTS: Older adults (>50 years) with recently diagnosed unilateral nAMD with a fellow (study) eye free of nAMD. METHODS: Self-reported vision, Amsler, clinic-measured visual acuity (VA), fundus assessment, and spectral domain OCT. The reference standard is FFA. MAIN OUTCOME MEASURES: Sensitivity and specificity of the 5 index tests. RESULTS: Of 552 participants monitored for up to 3 years, 145 (26.3%) developed active nAMD in the study eye, of whom 120 had an FFA at detection and constituted the primary analysis cohort. Index test positives at nAMD detection in those confirmed by FFA were self-reported vision much worse (5), distortion on Amsler (33), 10-letter decrease in acuity from baseline (36), fundus examination (64), and OCT (110). Percentage index test sensitivities were: self-reported vision 4.2 (95% confidence interval [CI], 1.6-9.8); Amsler 33.7 (95% CI, 25.1-43.5); VA 30.0 (95% CI, 22.5-38.7); fundus examination 53.8 (95% CI, 44.8-62.5); and OCT 91.7 (95% CI, 85.2-95.6). All 5 index test specificities were high at 97.0 (95% CI, 94.6-98.5), 81.4 (95% CI, 76.4-85.5), 66.3 (95% CI, 61.0-71.1), 97.6 (95% CI, 95.3-98.9), and 87.8 (95% CI, 83.8-90.9), respectively. The combination of OCT with one other index test that was a secondary outcome measure increased sensitivity marginally and decreased specificity for all combinations except fundus examination. CONCLUSIONS: Tests of self-reported change in vision, unmasking of new distortion, measurements of acuity, and fundus checks to diagnose active nAMD performed poorly in contrast to OCT. Our findings support a change to guidelines in clinical practice to monitor for onset of nAMD.

Validity and reliability of subjective methods to assess sedentary behaviour in adults: a systematic review and meta-analysis.

BACKGROUND: Subjective measures of sedentary behaviour (SB) (i.e. questionnaires and diaries/logs) are widely implemented, and can be useful for capturing type and context of SBs. However, little is known about comparative validity and reliability. The aim of this systematic review and meta-analysis was to: 1) identify subjective methods to assess overall, domain- and behaviour-specific SB, and 2) examine the validity and reliability of these methods. METHODS: The databases MEDLINE, EMBASE and SPORTDiscus were searched up to March 2020. Inclusion criteria were: 1) assessment of SB, 2) evaluation of subjective measurement tools, 3) being performed in healthy adults, 4) manuscript written in English, and 5) paper was peer-reviewed. Data of validity and/or reliability measurements was extracted from included studies and a meta-analysis using random effects was performed to assess the pooled correlation coefficients of the validity. RESULTS: The systematic search resulted in 2423 hits. After excluding duplicates and screening on title and abstract, 82 studies were included with 75 self-reported measurement tools. There was wide variability in the measurement properties and quality of the studies. The criterion validity varied between poor-to-excellent (correlation coefficient [R] range - 0.01- 0.90) with logs/diaries (R = 0.63 [95%CI 0.48-0.78]) showing higher criterion validity compared to questionnaires (R = 0.35 [95%CI 0.32-0.39]). Furthermore, correlation coefficients of single- and multiple-item questionnaires were comparable (1-item R = 0.34; 2-to-9-items R = 0.35; ≥10-items R = 0.37). The reliability of SB measures was moderate-to-good, with the quality of these studies being mostly fair-to-good. CONCLUSION: Logs and diaries are recommended to validly and reliably assess self-reported SB. However, due to time and resources constraints, 1-item questionnaires may be preferred to subjectively assess SB in large-scale observations when showing similar validity and reliability compared to longer questionnaires. REGISTRATION NUMBER: CRD42018105994.

Home-hit improves muscle capillarisation and eNOS/NAD(P)Hoxidase protein ratio in obese individuals with elevated cardiovascular disease risk.

KEY POINTS: Obesity and sedentary behaviour are associated with capillary rarefaction and impaired muscle microvascular vasoreactivity, due to reduced nitric oxide bioavailability. Low-volume high-intensity interval training (HIT) is a time-efficient alternative to traditional moderate-intensity continuous training (MICT), but its effect on the muscle microvasculature has not been studied. The applicability of current laboratory- and gym-based HIT protocols for obese individuals with low fitness and mobility has been disputed by public health experts, who cite the strenuous nature and complex protocols as major barriers. Therefore, we developed a virtually supervised HIT protocol targeting this group that can be performed at home without equipment (Home-HIT). This study is the first to show that 12 weeks of virtually supervised Home-HIT in obese individuals with elevated cardiovascular disease risk leads to similar increases in capillarisation and eNOS/NAD(P)Hoxidase protein ratio within the muscle microvascular endothelium as virtually supervised home-based MICT and laboratory-based HIT, while reducing many of the major barriers to exercise. ABSTRACT: This study investigated the effect of a novel virtually supervised home-based high-intensity interval training (HIT) (Home-HIT) intervention in obese individuals with elevated cardiovascular disease (CVD) risk on capillarisation and muscle microvascular eNOS/NAD(P)Hoxidase ratio. Thirty-two adults with elevated CVD risk (age 36 ± 10 years; body mass index 34.3 ± 5 kg m-2 ; V̇O2peak 24.6 ± 5.7 ml kg min-1 ), completed one of three 12-week training programmes: Home-HIT (n = 9), laboratory-based supervised HIT (Lab-HIT; n = 10) or virtually supervised home-based moderate-intensity continuous training (Home-MICT; n = 13). Muscle biopsies were taken before and after training to assess changes in vascular enzymes, capillarisation, mitochondrial density, intramuscular triglyceride content and GLUT4 protein expression using quantitative immunofluorescence microscopy. Training increased V̇O2peak (P < 0.001), whole-body insulin sensitivity (P = 0.033) and flow-mediated dilatation (P < 0.001), while aortic pulse wave velocity decreased (P < 0.001) in all three groups. Immunofluorescence microscopy revealed comparable increases in total eNOS content in terminal arterioles and capillaries (P < 0.001) in the three conditions. There was no change in eNOS ser1177 phosphorylation (arterioles P = 0.802; capillaries P = 0.311), but eNOS ser1177 /eNOS content ratio decreased significantly following training in arterioles and capillaries (P < 0.001). Training decreased NOX2 content (arterioles P < 0.001; capillaries P < 0.001), but there was no change in p47phox content (arterioles P = 0.101; capillaries P = 0.345). All measures of capillarisation increased (P < 0.05). There were no between-group differences. Despite having no direct supervision during exercise, virtually supervised Home-HIT resulted in comparable structural and endothelial enzymatic changes in the skeletal muscle microvessels to the traditional training methods. We provide strong evidence that Home-HIT is an effective novel strategy to remove barriers to exercise and improve health in an obese population at risk of CVD.

Individual calibration of accelerometers in children and their health-related implications.

This study compared children's physical activity (PA) levels, the prevalence of children meeting current guidelines of ≥60 minutes of daily moderate to vigorous PA (MVPA), and PA-health associations using individually calibrated (IC) and empirical accelerometer cutpoints. Data from 75 (n = 32 boys) 10-12 year old children were included in this study. Clustered cardiometabolic (CM) risk, directly measured cardiorespiratory fitness (CRF), anthropometric and 7 day accelerometer data were included within analysis. PA data were classified using Froude anchored IC, Evenson et al. (Evenson, K. R., Catellier, D. J., Gill, K., Ondrak, K. S., & McMurray, R. G. (2008). Calibration of two objective measures of physical activity for children. Journal of Sports Sciences, 26(14), 1557-1565. doi:10.1080/02640410802334196) (Ev) and Mackintosh et al. (Mackintosh, K. A., Fairclough, S. J., Stratton, G., & Ridgers, N. D. (2012). A calibration protocol for population-specific accelerometer cutpoints in children. PLoS One, 7(5), e36919. doi:10.1371/journal.pone.0036919) (Mack) cutpoints. The proportion of the cohort meeting ≥60mins MVPA/day ranged from 37%-56% depending on the cutpoints used. Reported PA differed significantly across the cutpoint sets. IC LPA and MPA were predictors of CRF (LPA: standardised ß = 0.32, p = 0.002, MPA: standardised ß = 0.27 p = 0.013). IC MPA also predicted BMI Z-score (standardised ß = -0.35, p = 0.004). Ev VPA was a predictor of BMI Z-score (standardised ß = -0.33, p = 0.012). Cutpoint choice has a substantial impact on reported PA levels though no significant associations with CM risk were observed. Froude IC cutpoints represent a promising approach towards classifying children's PA data.

Reproducibility of four frequently used local heating protocols to assess cutaneous microvascular function.

BACKGROUND: Skin microvascular responses to local heating are frequently used to assess microvascular function. Several local heating protocols have been developed, all varying slightly in execution. The aim of this study was to determine the inter-day reproducibility of the four most commonly used local heating protocols in healthy young subjects. METHODS: Fifteen, healthy males (28±5yrs, BMI 25±2kg/m2) attended two experimental trials 2-7days apart. During each trial, baseline and maximal thermally stimulated forearm skin responses were examined simultaneously at four sites on the dominant forearm using laser Doppler flowmetry (LDF). The following heating protocols were adopted: 1. Rapid 39°C (0.5°C/5s), 2. Rapid 42°C (0.5°C/5s) 3. Gradual 42°C (0.5°C/2min 30s) and 4. Slow 42°C (0.5°C/5min). The coefficient of variation (CV) was calculated for absolute flux, cutaneous vascular conductance (CVC; flux/mean arterial pressure, MAP) and CVC expressed as a percentage of maximal CVC at 44°C (%CVCmax) at three different time points; baseline (33°C), plateau (39/42°C) and maximal (44°C). RESULTS: Reproducibility of baseline flux, CVC and %CVCmax was 17-29% across all protocols. During the plateau, Rapid, Gradual and Slow 42°C demonstrated a reproducibility of 13-18% for flux and CVC and 5-11% for %CVCmax. However, Rapid 39°C demonstrated a lower reproducibility for flux, CVC and %CVCmax (all 21%). Reproducibility at 44°C was 12-15% for flux and CVC across all protocols. CONCLUSION: This is the first study examining inter-day reproducibility across four local heating protocols. The good-to-moderate reproducibility of the Rapid, Gradual and Slow 42°C protocols support their (simultaneous) use to assess microvascular function. Using Rapid 39°C may require a greater number of subjects to detect differences within subjects.

Sedentary Behavior and Cardiovascular Disease Risk: Mediating Mechanisms.

Sedentary behavior has a strong association with cardiovascular disease (CVD) risk, which may be independent of physical activity. To date, the mechanism(s) that mediate this relationship are poorly understood. We hypothesize that sedentary behavior modifies key hemodynamic, inflammatory, and metabolic processes resulting in impaired arterial health. Subsequently, these vascular impairments directly and indirectly contribute to the development of CVD.

Utility of three anthropometric indices in assessing the cardiometabolic risk profile in children.

OBJECTIVES: To evaluate the ability of BMI, WC, and WHtR to identify increased cardiometabolic risk in pre-adolescents. METHODS: This is a cross-sectional study involving 192 children (10.92 ± 0.58 years, 56% female) from the United Kingdom between 2010 and 2013. Receiver operating characteristic curves determined the discriminatory ability of BMI, WC and WHtR to identify individuals with increased cardiometabolic risk (increased clustered triglycerides, HDL-cholesterol, systolic blood pressure, cardiorespiratory fitness, and glucose). RESULTS: A WHtR ≥ 0.5 increased the odds by 5.2 (95% confidence interval 2.6 - 10.3) of having increased cardiometabolic risk. Similar associations were observed for BMI and WC. Both BMI-z and WHtR were fair predictors of increased cardiometabolic risk, although BMI-z demonstrated the best trade-off between sensitivity and specificity, 76.1% and 63.6%, compared with 68.1% and 65.5% for WHtR. Cross-validation analysis revealed that BMI-z and WHtR correctly classified 84% of individuals (kappa score = 0.671, 95% CI 0.55, 0.79). The sensitivity of the cut-points suggests that 89.3% of individuals were correctly classified as being at risk with only 10.7% misdiagnosed whereas the specificity of the cut-points indicated that 77.8% of individuals were correctly identified as being healthy with 22.2% of individuals incorrectly diagnosed as being at risk. CONCLUSIONS: Findings suggest that WHtR provides similar cardiometabolic risk estimates to age and sex adjusted BMI.

Sex differences in vascular endothelial function and health in humans: impacts of exercise.

NEW FINDINGS: What is the topic of this review? This brief review discusses potential sex differences in arterial function across the age span, with special emphasis on the effects of oestrogen and testosterone on the vascular endothelium. What advances does it highlight? We discuss the relationship between the impacts of sex hormones on arterial function and health in the context of epidemiological evidence pertaining to the menopause and ageing. Studies performed in humans are emphasized, alongside insights from animal studies. Findings suggest that the combination of exercise and hormone administration should be potentially synergistic or additive in humans. This brief review presents historical evidence for the purported impacts of male and female sex hormones on the vasculature in humans, including effects on macro- and microvascular function and health. Impacts of ageing on hormonal changes and arterial function are considered in the context of the menopause. Physiological data are presented alongside clinical outcomes from large trials, in an attempt to rationalize disparate findings along the bench-to-bedside continuum. Finally, the theoretical likelihood that exercise and hormone treatment may induce synergistic and/or additive vascular adaptations is developed in the context of recent laboratory studies that have compared male and female responses to training. Differences between men and women in terms of the impact of age and cardiorespiratory fitness on endothelial function are addressed. Ultimately, this review highlights the paucity of high-quality and compelling evidence regarding the fundamental impact, in humans, of sex differences on arterial function and the moderating impacts of exercise on arterial function, adaptation and health at different ages in either sex.

Evaluation of sit-stand workstations in an office setting: a randomised controlled trial.

BACKGROUND: Excessive sitting time is a risk factor for cardiovascular disease mortality and morbidity independent of physical activity. This aim of this study was to evaluate the impact of a sit-stand workstation on sitting time, and vascular, metabolic and musculoskeletal outcomes in office workers, and to investigate workstation acceptability and feasibility. METHODS: A two-arm, parallel-group, individually randomised controlled trial was conducted in one organisation. Participants were asymptomatic full-time office workers aged ≥18 years. Each participant in the intervention arm had a sit-stand workstation installed on their workplace desk for 8 weeks. Participants in the control arm received no intervention. The primary outcome was workplace sitting time, assessed at 0, 4 and 8 weeks by an ecological momentary assessment diary. Secondary behavioural, cardiometabolic and musculoskeletal outcomes were assessed. Acceptability and feasibility were assessed via questionnaire and interview. ANCOVA and magnitude-based inferences examined intervention effects relative to controls at 4 and 8 weeks. Participants and researchers were not blind to group allocation. RESULTS: Forty-seven participants were randomised (intervention n = 26; control n = 21). Relative to the control group at 8 weeks, the intervention group had a beneficial decrease in sitting time (-80.2 min/8-h workday (95 % CI = -129.0, -31.4); p = 0.002), increase in standing time (72.9 min/8-h workday (21.2, 124.6); p = 0.007) and decrease in total cholesterol (-0.40 mmol/L  (-0.79, -0.003); p = 0.049). No harmful changes in musculoskeletal discomfort/pain were observed relative to controls, and beneficial changes in flow-mediated dilation and diastolic blood pressure were observed. Most participants self-reported that the workstation was easy to use and their work-related productivity did not decrease when using the device. Factors that negatively influenced workstation use were workstation design, the social environment, work tasks and habits. CONCLUSION: Short-term use of a feasible sit-stand workstation reduced daily sitting time and led to beneficial improvements in cardiometabolic risk parameters in asymptomatic office workers. These findings imply that if the observed use of the sit-stand workstations continued over a longer duration, sit-stand workstations may have important ramifications for the prevention and reduction of cardiometabolic risk in a large proportion of the working population. TRIAL REGISTRATION: ClinicalTrials.gov NCT02496507 .

Physical activity, cardiorespiratory fitness, and clustered cardiometabolic risk in 10- to 12-year-old school children: the REACH Y6 study.

OBJECTIVES: (1) Investigate whether clustered cardiometabolic risk score, cardiorespiratory fitness (CRF), sedentary time (ST), and body mass index Z-scores (BMI Z-scores), differed between participants that met and did not achieve ≥60 min of daily moderate to vigorous intensity physical activity (MVPA). (2) Compare clustered cardiometabolic risk score, BMI Z-score, ST, and MVPA by CRF status. METHODS: One hundred and one (n = 45 boys) 10- to 12-year-old participants took part in this cross-sectional study, conducted in Liverpool (Summer 2010) and Ulster (Spring 2011) UK. Assessments of blood markers, stature, sitting stature, body mass, waist circumference, flow mediated dilation (FMD), and resting blood pressure (BP) were completed. CRF (VO2 peak) was estimated using an individually calibrated treadmill protocol. Habitual MVPA and ST were assessed using an individually calibrated accelerometer protocol. Clustered cardiometabolic risk scores were calculated using blood markers, FMD (%), BP and anthropometric measures. Participants were classified as active (≥60 min MVPA) or inactive and as fit or unfit. Multivariate analysis of covariance (MANCOVA) was used to investigate differences in cardiometabolic risk, BMI Z-score, CRF, and ST by activity status. MANCOVA was also completed to assess differences in cardiometabolic risk, MVPA, ST, and BMI Z-score by fitness status. RESULTS: Inactive children exhibited significantly higher clustered cardiometabolic risk scores and ST, and lower CRF than active children. Unfit participants exhibited significantly higher clustered cardiometabolic risk scores, BMI Z-scores and ST and lower MVPA in comparison to fit participants. CONCLUSIONS: This study highlights the importance of children achieving 60 min MVPA daily and provides further evidence surrounding the importance of CRF for health.

Cardiorespiratory fitness predicts clustered cardiometabolic risk in 10-11.9-year-olds.

The aim of this study was to investigate levels of clustered cardiometabolic risk and the odds of being 'at risk' according to cardiorespiratory fitness status in children. Data from 88 10-11.9-year-old children (mean age 11.05 ± 0.51 years), who participated in either the REACH Year 6 or the Benefits of Fitness Circuits for Primary School Populations studies were combined. Waist circumference, systolic blood pressure, diastolic blood pressure, glucose, triglycerides, high-density lipoprotein cholesterol, adiponectin and C-reactive protein were assessed and used to estimate clustered cardiometabolic risk. Participants were classified as 'fit' or 'unfit' using recently published definitions (46.6 and 41.9 mL/kg/min for boys and girls, respectively), and continuous clustered risk scores between fitness groups were assessed. Participants were subsequently assigned to a 'normal' or 'high' clustered cardiometabolic risk group based on risk scores, and logistic regression analysis assessed the odds of belonging to the increased cardiometabolic risk group according to fitness. The unfit group exhibited significantly higher clustered cardiometabolic risk scores (p < 0.001) than the fit group. A clear association between fitness group and being at increased cardiometabolic risk (B = 2.509, p = 0.001) was also identified, and participants classed as being unfit were found to have odds of being classified as 'at risk' of 12.30 (95 % CI = 2.64-57.33). Conclusion Assessing cardiorespiratory fitness is a valid method of identifying children most at risk of cardiometabolic pathologies. The ROC thresholds could be used to identify populations of children most at risk and may therefore be used to effectively target a cardiometabolic risk-reducing public health intervention.

Lack of relationship between sedentary behaviour and vascular function in children.

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 < 0.001) and SB increased (499.1 ± 103.5-559 ± 81.6 min/day, P < 0.001) between the seasons, no relationship existed between changes in these variables. Our data suggest that sedentary behaviour and changes in sedentary behaviour are not associated with endothelial function in children.

Skeletal muscle properties and vascular function do not differ between healthy, young vegan and omnivorous men.

A vegan diet is associated with reduced cardiovascular morbidity and mortality, but protein deficiencies may be detrimental to skeletal muscle structure and function. The aim of this study was to compare the vascular and skeletal muscle properties between young, healthy, recreationally active habitual vegan (VEG) and omnivorous (OMN) men. Sixteen OMN and nine VEG underwent ultrasound scans to determine brachial artery flow-mediated dilation (FMD) and carotid artery intima-media thickness (cIMT) and vastus lateralis (VL) muscle thickness and fascicle pennation angle. Knee extension maximal voluntary isometric contraction (MVIC) force was assessed on an isokinetic dynamometer, and V˙O2max on a cycle ergometer and online gas analysis system. A three-day food diary determined habitual dietary behaviour. Bayesian analyses of independent groups provided "moderate" to "very strong" evidence for lower consumption of absolute (63±21 g/d vs. 98 ± 30 g/d; Bayes Factor (BF01) = 0.140) and relative (0.86 ± 0.29 g/kg/d vs.1.36 ± 0.52 g/kg/d; BF01 = 0.259) protein, absolute saturated fat (15.2 ± 7.9 g vs. 30.3 ± 11.8 g; BF01 = 0.089) and cholesterol (5.0 ± 6.0 mg vs. 337.9 ± 232.6 mg; BF01 = 0.019) in VEG compared to OMN, respectively. Further, there was "anecdotal" evidence to support no differences in FMD (3.37 ± 3.31% vs. 4.58 ± 5.82%; BF01 = 2.591), cIMT (0.51 ± 0.07 mm vs. 0.49 ± 0.04 mm; BF01 = 2.510), VL thickness (26.1 ± 3.7 mm vs. 27.8 ± 6.4 mm; BF01 = 2.726), fascicle pennation angle (16.6 ± 4.7° vs. 17.7 ± 3.7°; BF01 = 2.844), MVIC (627 ± 182 N vs. 551 ± 102 N; BF01 = 1.656) or V˙O2max (40.8 ± 9.8 ml/kg/min vs. 35.8 ± 5.2 ml/kg/min; BF01 = 1.218) between VEG and OMN, respectively. Despite marked differences in habitual nutrient intake, healthy, young vegan and omnivorous men did not differ regarding vascular and skeletal muscle structure and function, or cardiovascular fitness.

Perceptions of Antenatal Exercise in Pregnant Females and the Impact of COVID-19.

Exercise during pregnancy presents many benefits for the mother and baby. Yet, pregnancy is characterised by a decrease in exercise. Studies have reported barriers to antenatal exercise. The coronavirus (COVID-19) pandemic may have further exacerbated barriers to antenatal exercise as pregnant females faced many challenges. Rich, in-depth exploration into pregnant female's perceived barriers to antenatal exercise during COVID-19 is imperative. Questionnaires reporting physical activity levels were completed by all participants (n = 14). Semi-structured interviews were conducted between November 2020 and May 2021 in the UK. Interviews were analysed using thematic analysis and revealed four main themes: 'Perceptions of being an active person shaping activity levels in pregnancy', 'How do I know what is right? Uncertainty, seeking validation and feeling informed', 'Motivators to antenatal exercise' and 'A process of adaptations and adjustment'. Findings indicate that the COVID-19 pandemic exacerbated barriers to antenatal exercise and highlight the importance of direct psychosocial support and clear, trustworthy information. Findings also support the fundamental need for better education amongst healthcare professionals regarding antenatal exercise.

Exercise-mediated changes in conduit artery wall thickness in humans: role of shear stress.

Episodic increases in shear stress have been proposed as a mechanism that induces training-induced adaptation in arterial wall remodeling in humans. To address this hypothesis in humans, we examined bilateral brachial artery wall thickness using high-resolution ultrasound in healthy men across an 8-wk period of bilateral handgrip training. Unilaterally, shear rate was attenuated by cuff inflation around the forearm to 60 mmHg. Grip strength, forearm volume, and girth improved similarly between the limbs. Acute bouts of handgrip exercise increased shear rate (P < 0.005) in the noncuffed limb, whereas cuff inflation successfully decreased exercise-induced increases in shear. Brachial blood pressure responses similarly increased during exercise in both the cuffed and noncuffed limbs. Handgrip training had no effect on baseline brachial artery diameter, blood flow, or shear rate but significantly decreased brachial artery wall thickness after 6 and 8 wk (ANOVA, P < 0.001) and wall-to-lumen ratio after week 8 (ANOVA, P = 0.005). The magnitude of decrease in brachial artery wall thickness and wall-to-lumen ratio after exercise training was similar in the noncuffed and cuffed arms. These results suggest that exercise-induced changes in shear rate are not obligatory for arterial wall remodeling during a period of 8 wk of exercise training in healthy humans.

Endothelial function and carotid intima-medial thickness in adolescents with type 2 diabetes mellitus.

OBJECTIVE: We assessed the effect of type 2 diabetes mellitus and obesity on flow-mediated dilation (FMD) and endothelial-dependent vasodilation and carotid intima-medial thickness (cIMT) in young people. STUDY DESIGN: Adolescents were recruited in 3 groups: subjects with type 2 diabetes mellitus (n = 15), subjects who were obese and non-insulin resistant (n = 13), and lean control subjects (n = 13). Body mass index was similar in subjects with obesity and subjects with type 2 diabetes mellitus, but higher compared with that of lean control subjects (both P < .001). Brachial artery FMD and cIMT were assessed by using Duplex ultrasound scanning imaging. RESULTS: There were no significant differences in brachial or common carotid arterial diameters in the groups. cIMT was significantly greater in the group with type 2 diabetes mellitus (0.54 ± 0.01mm) compared with both the lean control (0.46 ± 0.02 mm, P < .001) and obese control (0.46 ± 0.02 mm, P < .01) groups. FMD was significantly decreased in the group with type 2 diabetes mellitus (7.98% ± 0.54%) compared with the lean group (10.40% ± 1.00%, P < .05). CONCLUSIONS: Measures of vascular health were impaired in adolescents with type 2 diabetes mellitus compared with lean and obese adolescents who were not insulin resistant. Measures of arterial function and structure may provide pre-clinical measures of cardiovascular disease in young people at elevated risk.

The Effect of Exercise During Pregnancy on Maternal and Offspring Vascular Outcomes: a Pilot Study.

The aim of this pilot study is to obtain estimates for the change in maternal cerebrovascular (primary) and offspring vascular structure (secondary) during healthy pregnancy that includes structured exercise. Eighteen pregnant women self-assigned to a moderate-intensity aerobic exercise intervention or a control group. Maternal cerebral blood flow (CBF) at the middle cerebral artery, cerebro- and peripheral-vascular function was assessed at the end of each trimester. Offspring carotid artery intima-media thickness (IMT) was measured within 12 weeks of birth. For exploratory purposes, we performed statistical analysis to provide estimates of the change for primary and secondary outcome variables. Maternal CBF reduced (- 8 cm s-1 [- 14 to - 2]) with evidence of change to cerebral autoregulation (normalised gain: 0.12 %cm s-1% mmHg-1mmHg/% [- 0.18 to 0.40]) during pregnancy. Offspring carotid IMT was smaller in the exercise group (- 0.04 mm [- 0.12-0.03]) compared with controls. Based upon this data, a sample size of 33 and 57 in each group is required for low-frequency normalised gain and offspring IMT, respectively. This would provide 90% power to detect statistically significant (P < 0.05) between group differences in a randomised controlled trial. CBF is reduced in pregnancy, possibly due to reduced vascular resistance and altered maternal cerebral autoregulation. Maternal exercise had negligible effects on cerebrovascular adaptation to pregnancy, but we observed lower offspring carotid artery wall thickness following maternal exercise. Our directional findings and sample size estimations should be explored in a fully powered randomised control trial.Clinical trial registration: The trial was registered on March 14th at https://register.clinicaltrials.gov (NCT03079258). Participant enrolment began on 3rd April 2016.

Are acute sitting-induced changes in inflammation and cerebrovascular function related to impaired mood and cognition?

PURPOSE: Sedentary behaviour is negatively associated with mood and cognition, yet how acute sitting contributes to these overall associations is unknown. Since sitting heightens inflammation and impairs cerebrovascular function, this study investigated the hypothesis that these sitting-induced changes are related to impaired mood and cognition. METHODS: Twenty-five healthy desk workers (18 male, 28.3 ± 7.5 years, BMI: 24.2 ± 3.3 kg∙m-2) were recruited. During laboratory visit one, participants were familiarised with cognitive performance tests measuring executive function, attention and working memory. During laboratory visit two, participants completed 6 h of continuous, uninterrupted sitting. At baseline and after 6 h, serum markers of inflammation, middle cerebral artery blood flow velocity (MCAv), cerebrovascular carbon dioxide reactivity (CVR), dynamic cerebral autoregulation (CA), cognitive performance and mood (positive and negative affect, alert, contented and calm) were assessed. Data were analysed using paired-samples t tests and correlation analyses. RESULTS: Following sitting, C-reactive protein (∆-1.0 µg/ml) and tissue plasminogen activator (∆-360.4 pg/ml) decreased (p < 0.05), MCAv reduced (∆-2.9 cm∙s-1, p = 0.012) and normalised gain increased in the very low frequency range, indicating impaired CA (∆ + 0.22%·mmHg-1, p = 0.016). Positive affect (∆-4.6, p < 0.001), and alert (∆-10.6 p = 0.002) and contented (∆-7.4, p = 0.006) mood states also decreased following sitting. No significant changes in interleukin-6, tumour necrosis factor-alpha, von Willebrand factor, CVR or cognitive performance were observed (p > 0.05). The observed changes in inflammation and cerebrovascular function were not related to changes in mood (p > 0.05). CONCLUSION: Alterations in inflammation or cerebrovascular function following six hours of prolonged, uninterrupted sitting are not related to the observed reductions in mood, indicating other mechanisms underlie the relationship between acute sitting and mood disturbances.