Optimizing Blood Glucose Control through the Timing of Exercise in Pregnant Individuals Diagnosed with Gestational Diabetes Mellitus.

This study aimed to evaluate the effectiveness of moderate intensity walking on postprandial blood glucose control for pregnant individuals with (GDM) and without gestational diabetes mellitus (NON-GDM). Using a randomized cross-over design, individuals completed 5 days of exercise (three 10-min walks immediately after eating (SHORT), or one 30-min walk (LONG) outside of 1 h after eating). These protocols were preceded and separated by 2-days of habitual exercise (NORMAL). Individuals were instrumented with a continuous glucose monitor, a physical activity monitor for 14-days, and a heart rate monitor during exercise. Participants completed a physical activity enjoyment scale (PACES) to indicate their protocol preference. The GDM group had higher fasting, 24-h mean, and daily peak glucose values compared to NON-GDMs across all conditions (effect of group, p = 0.02; p = 0.02; p = 0.03, respectively). Fasting, 24-h mean, and daily peak glucose were not influenced by the SHORT or LONG exercise (effect of intervention, p > 0.05). Blood glucose values were higher among the GDM group for at least 1 h after eating, yet the exercise intervention had no effect on 1 or 2 h postprandial glucose values (effect of intervention, p > 0.05). Physical activity outcomes (wear time, total activity time, and time spent on each intensity) were not different between the groups nor interventions (effect of group, p > 0.05; effect of intervention, p > 0.05,). There were no differences between the groups or interventions for the PACES score (effect of group, p > 0.05; effect of intervention, p > 0.05). To conclude, there were no differences between the groups or exercise protocols on blood glucose control. More research is warranted to elucidate higher exercise volumes in this outcome for individuals with GDM.

Muscle sympathetic nerve activity during pregnancy: A systematic review and meta-analysis.

We conducted a systematic review and meta-analysis to quantify the impact of healthy and complex pregnancy on muscle sympathetic nerve activity (MSNA) at rest, and in response to stress. Structured searches of electronic databases were performed until February 23, 2022. All study designs (except reviews) were included: population (pregnant individuals); exposures (healthy and complicated pregnancy with direct measures of MSNA); comparator (individuals who were not pregnant, or with uncomplicated pregnancy); and outcomes (MSNA, BP, and heart rate). Twenty-seven studies (N = 807) were included. MSNA burst frequency was higher in pregnancy (n = 201) versus non-pregnant controls (n = 194) (Mean Differences [MD], MD: 10.6 bursts/min; 95% CI: 7.2, 14.0; I2  = 72%). Accounting for the normative increase in heart rate with gestation, burst incidence was also higher during pregnancy (Pregnant N = 189, non-pregnant N = 173; MD: 11 bpm; 95% CI: 8, 13 bpm; I2  = 47%; p < 0.0001). Meta-regression analyses confirmed that although sympathetic burst frequency and incidence are augmented during pregnancy, this was not significantly associated with gestational age. Compared to uncomplicated pregnancy, individuals with obesity, obstructive sleep apnea, and gestational hypertension exhibited sympathetic hyperactivity, while individuals with gestational diabetes mellitus or preeclampsia did not. Uncomplicated pregnancies exhibited a lesser response to head-up tilt, but an exaggerated sympathetic responsiveness to cold pressor stress compared to non-pregnant individuals. MSNA is higher in pregnant individuals and further increased with some, but not all pregnancy complications. PROSPERO registration number: CRD42022311590.

The sympathetic nervous system in healthy and hypertensive pregnancies: physiology or pathology?

NEW FINDINGS: What is the topic of this review? Sympathoexcitation in both healthy and hypertensive pregnancies, and concurrent adaptations along the neurovascular cascade. What advances does it highlight? Known and plausible adaptations along the neurovascular cascade which may offset elevated MSNA in normotensive pregnancy while also highlighting knowledge gaps regarding understudied pathways. ABSTRACT: The progression from conception through to the postpartum period represents an extraordinary period of physiological adaptation in the mother to support the growth and development of the fetus. Healthy, normotensive human pregnancies are associated with striking increases in both plasma volume and sympathetic nerve activity, yet normal or reduced blood pressure; it represents a unique period of apparent healthy sympathetic hyperactivity. However, how this normal blood pressure is achieved in the face of sympathoexcitation, and the mechanisms responsible for this increased activity are unclear. Importantly, sympathetic activation has been implicated in hypertensive pregnancy disorders - the leading causes of maternal-fetal morbidity and mortality in the developed world. An understudied link between pregnancy and the development of maternal hypertension may lie in the sympathetic nervous system regulation of blood pressure. This brief review presents the latest data on sympathoexcitation in both healthy and hypertensive pregnancies, and concurrent adaptations along the neurovascular cascade.

Exercise training and vascular function in postmenopausal individuals: a systematic review and meta-analysis.

IMPORTANCE: Cardiovascular disease (CVD) is a leading cause of morbidity and mortality for menopausal individuals. Flow-mediated dilation (FMD), a surrogate marker of CVD, improves with aerobic exercise training in healthy and nonhealthy cohorts. However, systematic evaluation and precise estimate of this effect for menopausal individuals are unknown. OBJECTIVE: We conducted a systematic review with meta-analysis to evaluate the influence of exercise training on FMD in postmenopausal individuals. EVIDENCE REVIEW: Studies were identified from systematic search of major electronic databases (PubMed, ScienceDirect, and Cochrane Library) from inception to February 2021. Healthy, postmenopausal individuals were included, following an aerobic exercise intervention assessing FMD. A random-effects meta-analysis was used to calculate a pooled effect size (mean difference [MD]) with 95% confidence interval. Heterogeneity was assessed using I2 statistics. Metaregression was used to assess the association between changes in FMD and physical characteristics (eg, blood pressure, age, baseline FMD) and intervention details (metabolic equivalents and change in maximal oxygen uptake [∆V˙ o2max ]). For variables that significantly correlated, a multiple metaregression model was used to assess the accounted variance in between-study ∆FMD%. Study quality was assessed using the National Heart, Lung, and Blood Institute assessment tool. FINDINGS: Nine studies, including 11 interventions (6 controlled interventions and 5 pre-post interventions; N = 182), with age range of 52 ± 4 to 64 ± 7 years underwent quantitative pooling of data. Exercise training significantly improved ∆FMD% (MD, 0.99; 95% confidence interval, 0.46-1.52; P < 0.001). Between-study heterogeneity was large and statistically significant ( I2 = 93.8%, P < 0.001). Post hoc analysis based on study design identified significant heterogeneity in the MD in ∆FMD% between controlled and pre-post study interventions ( P < 0.05). According to multiple metaregression, diastolic and systolic blood pressure and ∆V˙ o2max significantly predicted ∆FMD% ( Q = 15.74, df = 3, P < 0.01, R2 = 0.72). CONCLUSIONS AND RELEVANCE: Aerobic exercise training improves FMD for postmenopausal individuals, and this observation was greater among controlled versus pre-post interventions. A higher resting blood pressure and the greatest ∆V˙ o2max yielded the largest improvements in FMD.

Prenatal Exercise and Cardiovascular Health (PEACH) Study: impact of pregnancy and exercise on rating of perceived exertion during non-weight-bearing exercise.

The purpose of this study was to determine if rating of perceived exertion (RPE) during non-weight-bearing exercise is influenced by gestational age and exercise training. We conducted a randomized controlled trial to examine the influence of gestational age and exercise training (three to four times per week for 25-40 minutes at 50%-70% of heart rate reserve) on RPE during an exhaustive cycling exercise test. We observed no influence of gestational age, or exercise training status on RPE responses to non-weight-bearing exercise during pregnancy. Trial registration number: NCT02948439. Novelty: Gestational age and/or exercise training does not influence rate of perceived exertion during non-weight-bearing exercise.

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.

A Delphi Study to Identify Research Priorities Regarding Physical Activity, Sedentary Behavior and Sleep in Pregnancy.

This study aimed to produce a list of the top 10 research priorities regarding physical activity, sedentary behavior, and sleep in pregnancy. Using the Delphi methodology, pregnant/postpartum individuals (N = 118), exercise professionals and healthcare providers (N = 55) listed up to 10 questions perceived as unanswered regarding physical activity, sedentary behavior, and sleep in pregnancy (Round 1). Respondents rated the proposed questions on a Likert importance scale (Round 2), and the sum of ratings received were totaled. Questions of priority regarding physical activity among pregnant/postpartum individuals (N = 67), healthcare providers and exercise professionals (N = 22) pertained to exercise prescription, impact of exercise on maternal and fetal outcomes and impact of exercise on pregnancy conditions, special population groups and clinical education and access to information. Sedentary behavior priorities included the impact of sedentary behavior on maternal and fetal outcomes, sedentary recommendations and exercise and sedentary positioning. Sleep research priorities included the impact of pregnancy on sleep, safety, sleeping aids and the effect of exercise on sleep. Pregnant/postpartum women, healthcare providers and exercise professionals prioritized questions that have in part been addressed by existing research, highlighting a need for improved knowledge translation from research to practice. They have also identified novel questions that warrant prioritization within future research.

Access to and Quality of Healthcare for Pregnant and Postpartum Women During the COVID-19 Pandemic.

Introduction: During the COVID-19 pandemic, obstetric care has adopted new precautions to ensure services can be maintained for pregnant women. The aim of this study was to describe access to and quality of obstetric care for pregnant and postpartum women during the COVID-19 pandemic and to identify factors that predict quality of care at this time. Methods: Between May 3 and June 28, 2020, we recruited women who were pregnant or within the first 6 months after delivery to participate in an online survey. This included questions on access to obstetric healthcare (type and place of health care provider, changes to obstetric appointments/services, appointment preferences) and the Quality of Prenatal Care Questionnaire (QPCQ). Results: Of the 917 eligible women, 612 (67%) were pregnant and 305 (33%) were in the first 6 months after delivery. Sixty-two percent (n = 571) reported that COVID-19 had affected their healthcare; appointments were rearranged, canceled or occurred via virtual means for 29% (n = 166), 29% (n = 167), and 31% (n = 175) of women, respectively. The majority preferred to physically attend appointments (74%; n = 676) and perceived the accompaniment of birth partners as important (77%; n = 471). Sixty-two percent (n = 380) were permitted a birth partner at delivery, 18% (n = 111) were unsure of the rules while 4% (n = 26) were not permitted accompaniment. During pregnancy, QPCQ was negatively associated with disruption to obstetric services including exclusion or uncertainty regarding birth partner permissions [F (7, 433) = 11.5, p < 0.001, R 2 = 0.16] while QPCQ was negatively associated with inadequate breastfeeding support postpartum [F (1, 147) = 12.05, p = 0.001, R 2 = 0.08]. Conclusion: Pregnant and postpartum have experienced disruption in their access to obstetric healthcare. Perceived quality of obstetric care was negatively influenced by cancellation of appointment(s), suspension of services and exclusion of birth partners at delivery. During this time, continuity of care can be fulfilled via virtual and/or phone appointments and women should receive clear guidance on changes to services including birth partner permissions to attend delivery.

The 9-Month Stress Test: Pregnancy and Exercise-Similarities and Interactions.

Of all physiological systems, the cardiovascular system takes on the most profound adaptation in pregnancy to support fetal growth and development. The adaptations that arise are systemic and involve structural and functional changes that can be observed at the cerebral, central, peripheral, and microvascular beds. This includes, although is not limited to, increased heart rate, stroke volume, and cardiac output with negligible change to blood pressure, reductions in vascular resistance, and cerebral blood flow velocity, systemic artery enlargement, and enhanced endothelial function. All of this takes place to accommodate blood volume expansion and ensure adequate fetal and maternal oxygen delivery. In some instances, the demand placed on the vasculature can manifest as cardiovascular maladaptation and thus, cardiovascular complications can arise. Exercise is recommended in pregnancy because of its powerful ability to reduce the incidence and severity of cardiovascular complications in pregnancy. However, the mechanism by which it acts is poorly understood. The first of our aims in this review was to describe the systemic adaptations that take place in pregnancy. Our second aim was to describe the influence of exercise on these systemic adaptations. It is anticipated that this review can comprehensively capture the extent of knowledge in this area while identifying areas that warrant further investigation.

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.

Cerebral and peripheral vascular differences between pre- and postmenopausal women.

OBJECTIVE: Menopause is associated with lower peripheral vascular function; however, cerebrovascular responses to this time-period are unclear. We aimed to describe peripheral vascular and cerebrovascular differences between pre- and postmenopausal women. METHODS: Fifty pre- and postmenopausal women (N = 100) underwent assessments of cerebral blood flow; cerebrovascular reactivity and autoregulation; carotid artery reactivity; brachial and femoral artery flow-mediated dilation; and carotid, brachial, and femoral artery intima-media thickness. Comparisons were made between pre- and postmenopausal women followed by a secondary analysis (N = 20) between late premenopausal women and those within 5 years of menopause using a general linear model. RESULTS: Cerebral blood flow (-11 [-17, -4 cm/s]; P = 0.03) and carotid reactivity (-2.3 [-4.3, -0.3%] P = 0.03) were lower postmenopause compared to premenopause, whereas cerebrovascular reactivity and autoregulation did not differ (P > 0.05). Postmenopausal women had a larger carotid (0.16 [0.13, 0.20 mm] P < 0.001), brachial (0.07 [0.03, 0.11 mm] P = 0.004), and femoral artery intima-media thickness (0.09 [0.05, 0.14 mm] P = 0.04), alongside lower brachial (-2.3 [-3.9, -0.7%] P = 0.004) and femoral artery flow-mediated dilation (-3.0 [-4.3, -1.8%] P < 0.001). In the secondary-analysis, early postmenopausal women had a lower femoral artery flow-mediated dilation (-1.9 [-3.9, -0.0%] P = 0.05) and larger carotid intima-media thickness (0.07 [0.00, 0.14 mm] P = 0.03) compared to late premenopausal women. CONCLUSIONS: Cerebral blood flow, carotid artery reactivity, peripheral vascular function, and structure are negatively affected by age. Preliminary data indicate that femoral artery function and carotid artery structure may be potentially impaired in early postmenopause compared with late premenopause. These findings suggest that conduit arteries susceptible to atherosclerosis may be important targets for lifestyle intervention in early menopause.

Fluctuation in shear rate, with unaltered mean shear rate, improves brachial artery flow-mediated dilation in healthy, young men.

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-min exposure to fluctuations in shear rate patterns, in the presence of unaltered mean shear rate, improves brachial artery flow-mediated dilation. Fifteen healthy men (27.3 ± 5.0 yr) completed the study. Bilateral brachial artery flow-mediated dilation was assessed before and after unilateral exposure to 30 min of intermittent negative pressure (10 s, -40mmHg; 7 s, 0 mmHg) to induce fluctuation in shear rate, while the contralateral arm was exposed to a resting period. Negative pressure significantly increased shear rate, followed by a decrease in shear rate upon pressure release (both P < 0.001). Across the 30-min intervention, mean shear rate was not different compared with baseline (P = 0.458). A linear mixed model revealed a significant effect of time 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 contralateral control arm (∆FMD +0.5%, P = 0.664). However, there was no effect for arm (P = 0.619) or interaction effect (P = 0.096). 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, represent a stimulus to acute change in endothelial function in healthy individuals. NEW & NOTEWORTHY Intermittent negative pressure applied to the forearm induced significant fluctuations in antegrade and retrograde shear rate, while mean shear was preserved relative to baseline. Our exploratory study revealed that brachial artery flow-mediated dilation was significantly improved following 30-min exposure to intermittent negative pressure. Fluctuations in blood flow or shear rate, with unaltered mean shear, may have important implications for vascular health; however, further research is required to identify the underlying mechanisms and potential long-term health benefits.

Relationship Between Endothelial Function and the Eliciting Shear Stress Stimulus in Women: Changes Across the Lifespan Differ to Men.

Background Premenopausal women have a lower incidence of cardiovascular disease, which may partly be due to a protective effect of estrogen on endothelial function. Animal studies suggest that estrogen may also improve the relationship between shear rate ( SR ) and endothelial function. We aimed to explore the relationship between endothelial function (ie, flow-mediated dilation [ FMD ]) and SR (ie, SR area under the curve [ SRAUC ]) in women versus men, and between pre- versus postmenopausal women. Methods and Results Brachial artery FMD and SRAUC were measured in accordance with expert-consensus guidelines in 932 healthy participants who were stratified into young adults (18-40 years, 389 men, 144 women) and older adults (>40 years, 260 men, 139 women). Second, we compared premenopausal (n=173) and postmenopausal women (n=110). There was evidence of a weak correlation between SRAUC and FMD in all groups but older men, although there was variation in strength of outcomes. Further exploration using interaction terms (age-sex× SRAUC ) in linear regression revealed differential relationships with FMD (young women versus young men [ß=-5.8-4, P=0.017] and older women [ß=-5.9-4, P=0.049]). The correlation between SRAUC and FMD in premenopausal women ( r2=0.097) was not statistically different from that in postmenopausal women ( r2=0.025; Fisher P=0.30). Subgroup analysis using stringent inclusion criteria for health markers (n=505) confirmed a stronger FMD - SRAUC correlation in young women compared with young men and older women. Conclusions Evidence for a stronger relationship between endothelial function and the eliciting SR stimulus is present in young women compared with men. Estrogen may contribute to this finding, but larger healthy cohorts are required for conclusive outcomes.