The effect of hyperoxia on muscle sympathetic nerve activity: a systematic review and meta-analysis

PURPOSE

We conducted a meta-analysis to determine the effect of hyperoxia on muscle sympathetic nerve activity in healthy individuals and those with cardio-metabolic diseases.

METHODS

A comprehensive search of electronic databases was performed until August 2022. All study designs (except reviews) were included: population (humans; apparently healthy or with at least one chronic disease); exposures (muscle sympathetic nerve activity during hyperoxia or hyperbaria); comparators (hyperoxia or hyperbaria vs. normoxia); and outcomes (muscle sympathetic nerve activity, heart rate, blood pressure, minute ventilation). Forty-nine studies were ultimately included in the meta-analysis.

RESULTS

In healthy individuals, hyperoxia had no effect on sympathetic burst frequency (mean difference [MD] - 1.07 bursts/min; 95% confidence interval [CI] - 2.17, 0.04bursts/min; P = 0.06), burst incidence (MD 0.27 bursts/100 heartbeats [hb]; 95% CI - 2.10, 2.64 bursts/100 hb; P = 0.82), burst amplitude (P = 0.85), or total activity (P = 0.31). In those with chronic diseases, hyperoxia decreased burst frequency (MD - 5.57 bursts/min; 95% CI - 7.48, - 3.67 bursts/min; P < 0.001) and burst incidence (MD - 4.44 bursts/100 hb; 95% CI - 7.94, - 0.94 bursts/100 hb; P = 0.01), but had no effect on burst amplitude (P = 0.36) or total activity (P = 0.90). Our meta-regression analyses identified an inverse relationship between normoxic burst frequency and change in burst frequency with hyperoxia. In both groups, hyperoxia decreased heart rate but had no effect on any measure of blood pressure.

CONCLUSION

Hyperoxia does not change sympathetic activity in healthy humans. Conversely, in those with chronic diseases, hyperoxia decreases sympathetic activity. Regardless of disease status, resting sympathetic burst frequency predicts the degree of change in burst frequency, with larger decreases for those with higher resting activity.

"Is It Realistic?": A Qualitative Study of the Experiences of Elite Women Athletes Considering Parenthood

BACKGROUND AND OBJECTIVE

As the visibility and acceptance of athlete-mothers increase, so does the number of women athletes considering parenthood. Yet, many athletes struggle with the decision to become a parent while competing at the elite level due to the significant changes and uncertainties that have been reported by pregnant and parenting athletes. The experiences of women athletes considering parenthood are under-represented in the vast sport literature but are necessary for developing evidenced-based policies and practices that can support women's equitable participation in high-performance sport contexts. Thus, the purpose of this qualitative study was to describe the experiences of elite women athletes that are considering parenthood.

METHODS

Participants were ten elite North American athletes (29-36 years) who are considering becoming parents in the next 5 years. Each participant self-identified as a woman and competed at the highest level in their respective sport. Data were generated via one-on-one semi-structured interviews that were audio-recorded, transcribed verbatim, and analyzed through a process of content analysis.

RESULTS

The experiences of elite women athletes considering parenthood are represented by five themes: (a) calls for essential mandates and leadership, (b) how do you support yourself?, (c) hesitation of body changes, (d) age inequities, and (e) being proactive about reproductive health. Such findings support an in-depth understanding of gender-specific stressors that limit women's equitable participation in high-performance contexts.

CONCLUSION

This research is grounded in the voices of elite women athletes and identifies actionable steps necessary for research and culture change. Findings provide necessary evidence to inform the development of sport policies to support those athletes that are considering becoming parents.

Clinical and exercise professional opinion of return-to-running readiness after childbirth: an international Delphi study and consensus statement

Female athletes have identified a lack of guidance as a barrier to successfully returning to running postpartum, and existing guidelines are vague. Our aim was to define the current practice of determining postpartum run-readiness through a consensus survey of international clinicians and exercise professionals in postpartum exercise to assist clinicians and inform sport policy changes.A three-round Delphi approach was used to gain international consensus from clinicians and exercise professionals on run-readiness postpartum. Professionals who work with postpartum runners participated in an online survey to answer open-ended questions about the following postpartum return-to-running topics: definitions (runner and postpartum), key biopsychosocial milestones that runners need to meet, recommended screening, timeline to initiate running, support items, education topics and factors that contribute to advising against running. Consensus was defined as ≥75% participant agreement.One hundred and eighteen professionals participated in round I, 107 participated in round II (response rate 90.6%) and 95 participated in round III (response rate 80.5%). Responses indicated that, following a minimum 3-week period of rest and recovery, an individualised timeline and gradual return to running progression can be considered. Screening for medical and psychological concerns, current physical capacity, and prior training history is recommended prior to a return to running.This study proposes recommendations for the initial guidance on return-to-running postpartum, framed in the context of current research and consensus from professionals. Future research is needed to strengthen and validate specific recommendations and develop guidelines for best practice when returning-to-running after childbirth.

Clinical and exercise professional opinion on designing a postpartum return-to-running training programme: an international Delphi study and consensus statement

Returning to running postpartum presents challenges such as musculoskeletal pain and pelvic floor dysfunction for some females, but there is little guidance on developing and progressing postpartum training programmes. This study aims to establish expert consensus recommendations on designing and modifying a postpartum return-to-running training programme, highlight costs and access to qualified professionals as potential barriers and discuss clinical, research and sports policy implications.A three-round Delphi survey of clinical and exercise professionals working with postpartum runners was conducted. Round I consisted of open-ended questions related to designing the training plan, modifications based on biopsychosocial factors, key muscle groups to train and referral and payment sources. Rounds II and III involved Likert-scale voting to identify consensus (≥75% agreement).118 participants completed Round I, 107 completed Round II (response rate 90.6%) and 95 completed Round III (response rate 80.5%). Consensus was reached in 42/47 (89%) statements, including recommendations for a period of relative rest, gradual increases in duration and intensity, starting with a walk-run protocol and incorporating strength training. Training should be modified based on musculoskeletal or pelvic symptoms, sleep, mental health, lactation or energy availability concerns. Cost and access to experienced postpartum running professionals were identified as potential barriers for runners to receive care.Consensus recommendations for a postpartum return-to-running programme include an individualised exercise prescription, gradual increases in physical activity, walk-run protocols and targeted muscle strengthening. Further research and improved access to clinical and exercise professionals are needed to inform and facilitate best practices.

Filling the evidence void: exploration of coach and healthcare provider experiences working with pregnant and postpartum elite athletes - a qualitative study

OBJECTIVE

Recent research grounded in the experiences of elite female athletes has shed light on the complex challenges of navigating sport environments that do not support or value pregnant or postpartum athletes. The purpose of this study was to explore the unique experiences of coaches and healthcare providers working with pregnant and postpartum elite athletes, and to identify actionable steps for research, policy and culture change to support them.

METHODS

Sixteen participants (five coaches, three physicians and eight physiotherapists), who have worked with pregnant and/or postpartum elite athletes within the last 5 years, participated in this qualitative study. Thirteen participants self-identified as women, and three as men. Data were generated via semistructured one-on-one interviews that were audiorecorded, transcribed verbatim and analysed through a process of content analysis.

RESULTS

The findings of this research are represented by five main themes: (a) lack of female athlete reproductive research, (b) need for evidence-informed education and training, (c) need to develop evidence-based progression for sport participation in pregnancy and postpartum, (d) open communication to support athlete-centred care and (e) essential supports and changes required for pregnant/postpartum athletes.

CONCLUSION

Findings from this study, which are grounded in the unique perspectives of coaches and healthcare providers, outline specific recommendations to inform policy and practices that support athletes through the perinatal period, such as developing evidence-based return-to-sport protocols.

The effect of hypoxemia on muscle sympathetic nerve activity and cardiovascular function: a systematic review and meta-analysis

We conducted a systematic review and meta-analysis to determine the effect of acute poikilocapnic, high-altitude, and acute isocapnia hypoxemia on muscle sympathetic nerve activity (MSNA) and cardiovascular function. A comprehensive search across electronic databases was performed until June 2021. All observational designs were included: population (healthy individuals); exposures (MSNA during hypoxemia); comparators (hypoxemia severity and duration); outcomes (MSNA; heart rate, HR; and mean arterial pressure, MAP). Sixty-one studies were included in the meta-analysis. MSNA burst frequency increased by a greater extent during high-altitude hypoxemia [P < 0.001; mean difference (MD), +22.5 bursts/min; confidence interval (CI) = -19.20 to 25.84] compared with acute poikilocapnic hypoxemia (P < 0.001; MD, +5.63 bursts/min; CI = -4.09 to 7.17) and isocapnic hypoxemia (P < 0.001; MD, +4.72 bursts/min; CI = -3.37 to 6.07). MSNA burst amplitude was only elevated during acute isocapnic hypoxemia (P = 0.03; standard MD, +0.46 au; CI = -0.03 to 0.90), and MSNA burst incidence was only elevated during high-altitude hypoxemia [P < 0.001; MD, 33.05 bursts/100 heartbeats; CI = -28.59 to 37.51]. Meta-regression analysis indicated a strong relationship between MSNA burst frequency and hypoxemia severity for acute isocapnic studies (P < 0.001) but not acute poikilocapnia (P = 0.098). HR increased by the same extent across each type of hypoxemia [P < 0.001; MD +13.81 heartbeats/min; 95% CI = 12.59-15.03]. MAP increased during high-altitude hypoxemia (P < 0.001; MD, +5.06 mmHg; CI = 3.14-6.99), and acute isocapnic hypoxemia (P < 0.001; MD, +1.91 mmHg; CI = 0.84-2.97), but not during acute poikilocapnic hypoxemia (P = 0.95). Both hypoxemia type and severity influenced sympathetic nerve and cardiovascular function. These data are important for the better understanding of healthy human adaptation to hypoxemia.

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.

Maternal and Fetal Cardiovascular Responses to Acute High-Intensity Interval and Moderate-Intensity Continuous Training Exercise During Pregnancy: A Randomized Crossover Trial

OBJECTIVE

We aimed to compare maternal and fetal cardiovascular responses to an acute bout of high-intensity interval training (HIIT) versus moderate-intensity continuous training (MICT) during pregnancy.

METHODS

Fifteen women with a singleton pregnancy (27.3 ± 3.5 weeks of gestation, 33 ± 4 years of age) were recruited. Following a peak fitness test, participants engaged in a session of HIIT (10 × 1-min intervals ≥ 90% maximum heart rate [HRmax]) interspersed with 1 min of active recovery) and MICT (30 min at 64-76% HRmax) 48 h apart in random order. Maternal HR, blood pressure, middle (MCAv), and posterior cerebral artery blood velocity (PCAv), as well as respiratory measures were monitored continuously throughout HIIT/MICT. Fetal heart rate, as well as umbilical systolic/diastolic (S/D) ratio, resistive index (RI), and pulsatility index (PI) were assessed immediately before and after exercise.

RESULTS

Average maternal heart rate was higher for HIIT (82 ± 5% HRmax) compared with MICT (74 ± 4% HRmax; p < 0.001). During the HIIT session, participants achieved a peak heart rate of 96 ± 5% HRmax (range of 87-105% HRmax). Maternal cerebral blood velocities increased with exercise but was not different between HIIT and MICT for MCAv (p = 0.340) and PCAv (p = 0.142). Fetal heart rate increased during exercise (p = 0.244) but was not different between sessions (HIIT: Δ + 14 ± 7 bpm; MICT: Δ + 10 ± 10 bpm). Metrics of umbilical blood flow decreased with exercise and were not different between exercise sessions (PI: p = 0.707; S/D ratio: p = 0.671; RI: p = 0.792). Fetal bradycardia was not observed, and S/D ratio, RI, and PI remained within normal ranges both before and immediately after all exercise sessions.

CONCLUSIONS

An acute bout of HIIT exercise consisting of repeated 1-min near-maximal to maximal exertions, as well as MICT exercise is well tolerated by both mother and fetus.

CLINICAL TRIAL REGISTRATION

NCT05369247.

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.

Associations between demographic and parental factors and infant sleep characteristics

Although sleep problems are highly prevalent in infants, the intrinsic and extrinsic factors that influence sleep consolidation and regulation in this age group are not well understood. This study aimed to examine the cross-sectional associations of demographic and parental factors with infant sleep characteristics. Participants were 97 Canadian mother-infant dyads primarily from Edmonton, Alberta. Demographic factors (e.g., infant age), parenting practices (e.g., sleep position, sleep initiation methods), and infants sleep characteristics (e.g., the frequency of nighttime awakenings) were assessed using the Brief Infant Sleep Questionnaire. Maternal sleep characteristics (e.g., nighttime sleep duration) were assessed using Actigraph accelerometers. Infant age (mean = 4.24 ± 2.90) was associated with most infant sleep characteristics. In multiple regression models for infant nighttime sleep duration, after removing influential observations, a negative association for side (vs. prone) sleep position was, respectively, observed. In multiple regression models for the frequency of nighttime awakenings in infants, positive associations for infants falling asleep while feeding (vs. in bed alone) and side (vs. prone) sleep position were consistently observed after removing influential observations. Lower nighttime sleep efficiency (B =  - 0.08, 95%CI: - 0.13, - 0.02) and longer nighttime wake after sleep onset (B = 1.03, 95%CI: 0.41, 1.65) in mothers were associated with more frequent nighttime awakenings in infants. After removing influential observations, more frequent nighttime awakenings (B = 0.35; 95%CI: 0.09, 0.61) and longer total sleep duration (B = 0.33, 95%CI: 0.11, 0.55) in mothers were also associated with more frequent nighttime awakenings in infants. Sleep initiation methods with less parental involvement, and more continuous and efficient maternal nighttime sleep, tended to be associated with less interrupted infant sleep.

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.

Prenatal Exercise and Cardiovascular Health (PEACH) study: impact of meal timing and pre-exercise blood glucose values on glycemic responses to acute exercise in pregnancy

We retrospectively analyzed data from 28 participants engaging in moderate-intensity aerobic exercise (265 sessions; 25-40 min) between 18-34 weeks gestation (NCT02948439). The mean change in blood glucose (BG) from pre- to post-acute exercise session was -1.0 ± 1.2 mmol/L. Pre-exercise BG significantly predicted the change in BG (p < 0.001), even when controlling for meal timing, exercise duration, and gestational age. Hypoglycemia only occurred in 3% of sessions. Therefore, in healthy pregnancy the change in BG during exercise is small and primarily related to pre-exercise BG values.

Impact of heavy resistance training on pregnancy and postpartum health outcomes

INTRODUCTION AND HYPOTHESIS

Participation in Olympic weightlifting, the Valsalva maneuver, and acute or prolonged supine weightlifting during pregnancy are cautioned against; however, these recommendations are based on expert opinions as opposed to empirical evidence. The aim of this study was to examine the training and health outcomes of individuals who engaged in heavy resistance training during pregnancy.

METHODS

A total of 679 individuals who lifted at least 80% one-repetition maximum during pregnancy participated in an online survey.

RESULTS

Participants were primarily recreational athletes (88%, 332 out of 675) engaged in CrossFit™ (61%, 410 out of 675) and/or weightlifting (49%, 332 out of 675) during pregnancy. Most participants reported no complications during pregnancy or delivery (66%, 388 out of 589), whereas 57% (241 out of 426) reported urinary incontinence following pregnancy. Participants who maintained pre-pregnancy training levels until delivery reported significantly less reproductive complications than those who ceased training levels prior to delivery (p = 0.006). Most respondents engaged in Olympic lifting (72%, 311 out of 432) and lifting in a supine position (71%, 306 out of 437), whereas fewer reported use of the Valsalva maneuver during pregnancy (34%, 142 out of 412). Most returned to weightlifting following delivery (89%, 400 out of 447, average: 3.2 ± 3.0 months), including Olympic lifting (81%, 300 out of 372, average: 4.0 ± 3.4 months) and Valsalva (62%, 213 out of 341, average: 4.5 ± 3.6 months).

CONCLUSIONS

Individuals who engaged in heavy prenatal resistance training had typical perinatal and pelvic floor health outcomes that were not altered whether they engaged in, or avoided Olympic lifting, Valsalva or supine weightlifting.

Increased respiratory modulation of cardiovascular control reflects improved blood pressure regulation in pregnancy

Hypertensive pregnancy disorders put the maternal-fetal dyad at risk and are one of the leading causes of morbidity and mortality during pregnancy. Multiple efforts have been made to understand the physiological mechanisms behind changes in blood pressure. Still, to date, no study has focused on analyzing the dynamics of the interactions between the systems involved in blood pressure control. In this work, we aim to address this question by evaluating the phase coherence between different signals using wavelet phase coherence. Electrocardiogram, continuous blood pressure, electrocardiogram-derived respiration, and muscle sympathetic nerve activity signals were obtained from ten normotensive pregnant women, ten normotensive non-pregnant women, and ten pregnant women with preeclampsia during rest and cold pressor test. At rest, normotensive pregnant women showed higher phase coherence in the high-frequency band (0.15-0.4 Hz) between muscle sympathetic nerve activity and the RR interval, blood pressure, and respiration compared to non-pregnant normotensive women. Although normotensive pregnant women showed no phase coherence differences with respect to hypertensive pregnant women at rest, higher phase coherence between the same pairs of variables was found during the cold pressor test. These results suggest that, in addition to the increased sympathetic tone of normotensive pregnant women widely described in the existing literature, there is an increase in cardiac parasympathetic modulation and respiratory-driven modulation of muscle sympathetic nerve activity and blood pressure that could compensate sympathetic increase and make blood pressure control more efficient to maintain it in normal ranges. Moreover, blunted modulation could prevent its buffer effect and produce an increase in blood pressure levels, as observed in the hypertensive women in this study. This initial exploration of cardiorespiratory coupling in pregnancy opens the opportunity to follow up on more in-depth analyses and determine causal influences.

We're not Superhuman, We're Human: A Qualitative Description of Elite Athletes' Experiences of Return to Sport After Childbirth

BACKGROUND

A growing number of athletes return to elite sport following childbirth. Yet, they face significant barriers to do so safely and successfully. The experiences of elite athletes returning to sport following delivery are necessary to support evidence-informed policy.

OBJECTIVE

The purpose of this qualitative description was to describe the experiences of elite athletes as they returned to sport following childbirth, and to identify actionable steps for research, policy and culture-change to support elite athlete mothers.

METHODS

Eighteen elite athletes, primarily from North America, who had returned to sport following childbirth in the last 5 years were interviewed. Data were generated via one-on-one semi-structured interviews that were audio-recorded, transcribed verbatim, and analyzed through a process of content analysis.

RESULTS

The findings of this study are represented by one overarching theme: Need for More Time, and five main themes: (a) Training "New Bodies" Postpartum, (b) Injuries and Safe Return to Sport, (c) Breastfeeding While Training, (d) Critical Supports for Return to Sport, (e) Navigating Motherhood and Sport. The athletes identified the urgent need to develop best-practice policies and funding to support return to sport, as well as develop evidence-based return-to-sport protocols to support a safe and injury-free return.

CONCLUSION

Athletes shared detailed stories highlighting the challenges, barriers and successes elite athletes experience returning to elite-level sport following childbirth. Participants provided clear recommendations for policy and research to better support the next generation of elite athlete mothers.

TV time, physical activity, sedentary behaviour and cardiometabolic biomarkers in pregnancy-NHANES 2003-2006

OBJECTIVES

This study examined the impacts of individual and combined associations between moderate-to-vigorous physical activity (MVPA) and sedentary time (ST) (accelerometer-derived), as well as MVPA and television (TV) time (self-reported) on cardiometabolic biomarkers during pregnancy.

METHODS

Participants were 332 pregnant women from the 2003-2006 cycles of the National Health and Nutrition Examination Survey (NHANES). Multiple linear regression models were conducted to examine the relationships between individual and combinations of high/low MVPA, ST, and TV time with cardiometabolic biomarkers: body mass index (BMI), systolic blood pressure (SBP), diastolic blood pressure (DBP), high-density lipoprotein cholesterol (HDL), and C-reactive protein (CRP).

RESULTS

Women with high MVPA (≥ 17 min/day) compared to those with low MVPA (< 17 min/day) had significantly lower BMI. Women with low ST (< 503 min/day) compared to those with high ST (≥ 503 min/day) had significantly lower SBP and DBP. Women with low TV (< 3 h/day) compared to those with high TV (≥ 3 h/day) had significantly lower BMI and log-transformed CRP. Women with a combination of low ST/high MVPA had lower SBP and DBP (p_trend < 0.03). Women with a combination of low TV/high MVPA had lower BMI and log-transformed CRP (p_trend < 0.00).

CONCLUSION

We need to consider both physical activity and sedentary time for improved cardiometabolic health during pregnancy.

Influence of Obstructive Sleep Apnea Severity on Muscle Sympathetic Nerve Activity and Blood Pressure: a Systematic Review and Meta-Analysis

BACKGROUND

We conducted meta-analyses to identify relationships between obstructive sleep apnea (OSA) severity, muscle sympathetic nerve activity (MSNA), and blood pressure (BP). We quantified the effect of OSA treatment on MSNA.

METHODS

Structured searches of electronic databases were performed until June 2021. All observational designs (except reviews) were included: population (individuals with OSA); exposures (OSA diagnosis and direct measures of MSNA); comparator (individuals without OSA or different severity of OSA); outcomes (MSNA, BP, and heart rate).

RESULTS

Fifty-six studies (N=1872) were included. MSNA burst frequency was higher in OSA (27 studies; n=542) versus controls (n=488; mean differences [MDs], +15.95 bursts/min [95% CI, 12.6-17.6 bursts/min]; I²=86%). As was burst incidence (20 studies; n=357 OSA, n=312 Controls; MD, +22.23 bursts/100 hbs [95% CI, 18.49-25.97 bursts/100 hbs]; I²=67%). Meta-regressions indicated relationships between MSNA and OSA severity (burst frequency, R²=0.489; P<0.001; burst incidence, R²=0.573; P<0.001). MSNA burst frequency was related to systolic pressure (R²=0.308; P=0.016). OSA treatment with continuous positive airway pressure reduced MSNA burst frequency (MD, 11.91 bursts/min [95% CI, 9.36-14.47 bursts/min] I²=15%) and systolic (n=49; MD, 10.3 mm Hg [95% CI, 3.5-17.2 mm Hg]; I²=42%) and diastolic (MD, 6.9 mm Hg [95% CI, 2.3-11.6 mm Hg]; I²=37%) BP.

CONCLUSIONS

MSNA is higher in individuals with OSA and related to severity. This sympathoexcitation is also related to BP in patients with OSA. Treatment effectively reduces MSNA and BP, but limited data prevents an assessment of the link between these reductions. These data are clinically important for understanding cardiovascular disease risk in patients with OSA.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: CRD42021285159.

Glycemic response to acute high-intensity interval versus moderate-intensity continuous exercise during pregnancy

The present study investigated the glycemic response to an acute high-intensity interval training (HIIT) session (10 one-minute intervals ≥90% HRmax interspersed with one-minute of active recovery) versus a moderate-intensity continuous training (MICT) session (30 min at 64%-76% HRmax ) during pregnancy. Twenty-four normoglycemic females with a singleton pregnancy (27.8 ± 4.7 weeks of gestation, 31.5 ± 4.1 years of age, body mass index: 25.2 ± 11.3) participated in a randomized crossover design study. A flash glucose monitor and accelerometer were worn continuously for 7 days recording glycemic response, physical activity, and sleep. Nutritional intake and enjoyment of the exercise were self-reported. Average heart rate during exercise was higher for HIIT (82 ± 4% HRmax ) compared with MICT (74 ± 4% HRmax ; p < 0.001) and participants achieved a peak heart rate of 92 ± 3% during HIIT (range 85%-97% HRmax ) compared with 81 ± 4% during MICT (p < 0.001). The change in glucose values from pre-to-postexercise were not different between conditions (HIIT: -0.62 ± 1.00 mmol/L; MICT: -0.81 ± 1.05 mmol/L; p = 0.300) with the exception that fewer individuals experienced postexercise hypoglycemia immediately following HIIT compared with MICT (8% versus 33% respectively; p = 0.041). Other glucose variables was not different between exercise protocols. Physical activity (p = 0.07) and caloric intake did not differ (p = 0.10). The majority of participants preferred HIIT (87.5%) and had greater perceived enjoyment compared to MICT (HIIT: 7.8 ± 1.5; MICT: 6.6 ± 2.0; p = 0.015). Sleep duration was 52 ± 73 min longer after participating in HIIT compared with the night prior (main effect for time p = 0.017); no significant changes for MICT. Overall, an acute session of HIIT appears to be well tolerated and demonstrates no adverse effects on maternal glycemic response.

Exploring weight bias internalization in pregnancy

Background

Recent research has shown that pregnant individuals experience weight stigma throughout gestation, including negative comments and judgement associated with gestational weight gain (GWG). Weight bias internalization (WBI) is often a result of exposure to weight stigma and is detrimental to biopsychological health outcomes. The purpose of this study was to explore WBI in pregnancy and compare scores based on maternal weight-related factors including pre-pregnancy body mass index (BMI), obesity diagnosis and excessive GWG.

Methods

Pregnant individuals in Canada and USA completed a modified version of the Adult Weight Bias Internalization Scale. Self-reported pre-pregnancy height and weight were collected to calculate and classify pre-pregnancy BMI. Current weight was also reported to calculate GWG, which was then classified as excessive or not based on Institute of Medicine (2009) guidelines. Participants indicated if they were diagnosed with obesity by a healthcare provider. Inferential analyses were performed comparing WBI scores according to pre-pregnancy BMI, excessive GWG, and obesity diagnosis. Significance was accepted as p < 0.05 and effect sizes accompanied all analyses.

Result

336 pregnant individuals completed the survey, with an average WBI score of 3.9 ± 1.2. WBI was higher among those who had a pre-pregnancy BMI of obese than normal weight (p = 0.04, η² = 0.03), diagnosed with obesity than not diagnosed (p < 0.001, Cohen’s d = 1.3), and gained excessively versus not (p < 0.001, Cohen’s d = 1.2).

Conclusions

Pregnant individuals who have a higher BMI, obesity and gain excessively may experience WBI. Given that weight stigma frequently occurs in pregnancy, effective person-oriented strategies are needed to mitigate stigma and prevent and care for WBI.

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.

Physical activity before and during pregnancy and maternal mental health: A systematic review and meta-analysis of observational studies

OBJECTIVE

To examine the influence of physical activity before and during pregnancy on maternal mental health outcomes.

METHODS

Ten electronic databases were searched up to May 11, 2021. Studies of all observational designs (except case studies and reviews) were included, which contained information on the relevant population (women before and or during pregnancy), exposures (objective or subjective measures of physical activity), comparator (low or no physical activity), and outcomes (diagnosis and symptom severity of depression or anxiety, quality of life scores, stress and emotions).

RESULTS

Forty-four observational studies (N = 132,399) were included. 'Low' to 'very low' certainty evidence revealed that compared with low levels of PA during pregnancy, high levels of PA were associated with a reduced odds of developing prenatal depression (odds ratio (OR): 0.68, 95% confidence interval (CI): 0.58 to 0.80) and anxiety (OR: 0.67, 95% CI: 0.54 to 0.83). We also found a reduction in the severity of prenatal depressive symptoms (standardized mean difference (SMD): -0.37, 95% CI -0.57 to -0.17), prenatal anxiety symptoms (SMD: -0.45, 95% CI -0.64 to -0.27), and prenatal stress (SMD: -0.33, 95% CI -0.55 to -0.11), concurrent with improved quality of life (SMD: 0.38, 95% CI 0.23 to 0.54). PA before pregnancy did not impact the outcomes of interest.

CONCLUSION

Physical activity during pregnancy is associated with a reduction in the odds and severity of prenatal depression and anxiety, as well as reduced stress and improved quality of life. PROSPERO registration number: CRD42020208469.

Development of the Get Active Questionnaire for Pregnancy: Breaking down barriers to prenatal exercise

Evidence-based guidelines represent the highest level of scientific evidence to identify best-practices for clinical/public health. However, the availability of guidelines do not guarantee their use, targeted knowledge translation strategies and tools are necessary to help promote uptake. Following publication of the 2019 Canadian Guideline for Physical Activity throughout Pregnancy, the Get Active Questionnaire for Pregnancy, and an associated Health Care Provider Consultation Form for Prenatal Physical Activity were developed to promote guideline adoption and use amongst pregnant individuals and health care providers. This paper describes the process of developing these tools. First, a survey was administered to qualified exercise professionals to identify the barriers and facilitators in using existing prenatal exercise screening tools. A Working Group of researchers and stakeholders then convened to develop an evidence-informed exercise pre-participation screening tool for pregnant individuals, building from previous tool and survey findings. Finally, end-user feedback was solicited through a survey and key informant interviews to ensure tools are feasible and acceptable to use in practice. The uptake and use of these documents by pregnant individuals, exercise and health care professionals will be assessed in future studies. Novelty Bullets • Evidence supports the safety/benefits of exercise for most pregnant individuals; however, exercise is not recommended for a small number of individuals with specific medical conditions. • The Get Active Questionnaire for Pregnancy and Health Care Provider Consultation Form for Physical Activity during Pregnancy identify individuals where prenatal exercise may pose a risk, while reducing barriers to physical activity participation for the majority of pregnant individuals.

Pushing for change: a qualitative study of the experiences of elite athletes during pregnancy

Objectives

Athletes train and compete at the elite level during their reproductive years, yet sport policies that support pregnant athletes are lacking. The experiences of elite athletes during pregnancy are vastly under-represented, and such voices are needed to support evidence-informed policy. Thus, the purpose of this qualitative study was to describe the experiences of elite female athletes as they navigate pregnancy, and to identify sport policy considerations regarding participation during pregnancy.

Methods

Twenty athletes (mean age 35±5 years) who, within the last 5 years, had trained or competed at the elite level immediately prior to becoming pregnant were included. Data were generated via one-on-one semistructured interviews that were audio-recorded, transcribed verbatim and analysed through a process of content analysis.

Results

The findings of this study are represented by one overarching message: mother versus athlete, and five main themes: (1) pregnancy planning and fertility, (2) pregnancy disclosure and discrimination, (3) training pregnant athletic bodies, (4) safety concerns, and (5) supportive network and equitable funding.

Conclusion

In-depth stories shared by participants highlight the many significant decisions athletes must make as they navigate pregnancy alongside elite sport participation. The shared experiences of pregnant athletes highlight clear challenges that should be considered in the development of sport policy and practices that are inclusive and supportive of female athletes.

Evaluating Evidence-Based Content, Features of Exercise Instruction, and Expert Involvement in Physical Activity Apps for Pregnant Women: Systematic Search and Content Analysis

Background

Guidelines for physical activity and exercise during pregnancy recommend that all women without contraindications engage in regular physical activity to improve both their own health and the health of their baby. Many women are uncertain how to safely engage in physical activity and exercise during this life stage and are increasingly using mobile apps to access health-related information. However, the extent to which apps that provide physical activity and exercise advice align with current evidence-based pregnancy recommendations is unclear.

Objective

This study aims to conduct a systematic search and content analysis of apps that promote physical activity and exercise in pregnancy to examine the alignment of the content with current evidence-based recommendations; delivery, format, and features of physical activity and exercise instruction; and credentials of the app developers.

Methods

Systematic searches were conducted in the Australian App Store and Google Play Store in October 2020. Apps were identified using combinations of search terms relevant to pregnancy and exercise or physical activity and screened for inclusion (with a primary focus on physical activity and exercise during pregnancy, free to download or did not require immediate paid subscription, and an average user rating of ≥4 out of 5). Apps were then independently reviewed using an author-designed extraction tool.

Results

Overall, 27 apps were included in this review (Google Play Store: 16/27, 59%, and App Store: 11/27, 41%). Two-thirds of the apps provided some information relating to the frequency, intensity, time, and type principles of exercise; only 11% (3/27) provided this information in line with current evidence-based guidelines. Approximately one-third of the apps provided information about contraindications to exercise during pregnancy and referenced the supporting evidence. None of the apps actively engaged in screening for potential contraindications. Only 15% (4/27) of the apps collected information about the user’s current exercise behaviors, 11% (3/27) allowed users to personalize features relating to their exercise preferences, and a little more than one-third provided information about developer credentials.

Conclusions

Few exercise apps designed for pregnancy aligned with current evidence-based physical activity guidelines. None of the apps screened users for contraindications to physical activity and exercise during pregnancy, and most lacked appropriate personalization features to account for an individual’s characteristics. Few involved qualified experts during the development of the app. There is a need to improve the quality of apps that promote exercise in pregnancy to ensure that women are appropriately supported to engage in exercise and the potential risk of injury, complications, and adverse pregnancy outcomes for both mother and child is minimized. This could be done by providing expert guidance that aligns with current recommendations, introducing screening measures and features that enable personalization and tailoring to individual users, or by developing a recognized system for regulating apps.

Cerebrovascular and blood pressure responses during voluntary apneas are larger than rebreathing

Both voluntary rebreathing (RB) of expired air and voluntary apneas (VA) elicit changes in arterial carbon dioxide and oxygen (CO₂ and O₂) chemostimuli. These chemostimuli elicit synergistic increases in cerebral blood flow (CBF) and sympathetic nervous system activation, with the latter increasing systemic blood pressure. The extent that simultaneous and inverse changes in arterial CO₂ and O₂ and associated increases in blood pressure affect the CBF responses during RB versus VAs are unclear. We instrumented 21 healthy participants with a finometer (beat-by-beat mean arterial blood pressure; MAP), transcranial Doppler ultrasound (middle and posterior cerebral artery velocity; MCAv, PCAv) and a mouthpiece with sample line attached to a dual gas analyzer to assess pressure of end-tidal (P_ET)CO₂ and P_ETO₂. Participants performed two protocols: RB and a maximal end-inspiratory VA. A second-by-second stimulus index (SI) was calculated as P_ETCO₂/P_ETO₂ during RB. For VA, where P_ETCO₂ and P_ETO₂ could not be measured throughout, SI values were calculated using interpolated end-tidal gas values before and at the end of the apneas. MAP reactivity (MAPR) was calculated as the slope of the MAP/SI, and cerebrovascular reactivity (CVR) was calculated as the slope of MCAv or PCAv/SI. We found that compared to RB, VA elicited ~ fourfold increases in MAPR slope (P < 0.001), translating to larger anterior and posterior CVR (P ≤ 0.01). However, cerebrovascular conductance (MCAv or PCAv/MAP) was unchanged between interventions (P ≥ 0.2). MAP responses during VAs are larger than those during RB across similar chemostimuli, and differential CVR may be driven by increases in perfusion pressure.

Prenatal exercise and cardiovascular health (PEACH) study: impact of acute and chronic exercise on cerebrovascular hemodynamics and dynamic cerebral autoregulation

We performed a randomised controlled trial measuring dynamic cerebral autoregulation (dCA) using a sit-to-stand maneuver before (SS1) and following (SS2) an acute exercise test at 16-20 weeks gestation (trimester 2; TM2) and then again at 34-37 weeks gestation (third trimester; TM3). Following the first assessment, women were randomised into exercise training or control (standard care) groups; women in the exercise training group were prescribed moderate intensity aerobic exercise for 25-40 minutes on 3-4 days per week for 14±1weeks. Resting seated mean blood velocity in the middle cerebral artery (MCAv_mean) was lower in TM3 compared to TM2 but not impacted by exercise training intervention. dCA was not impacted by gestational age, or exercise training during SS1. During SS2, dCA was altered such that there were greater absolute and relative decreases in mean arterial blood pressure (MAP) and MCAv_mean, but this was not impacted by the intervention. There was also no difference in the relationship between the decrease in MCAv_mean compared to the decrease in MAP (%/%), or the onset of the regulatory response with respect to acute exercise, gestational age, or intervention; however, rate of regulation was faster in women in the exercise group following acute exercise (interaction effect, p=0.048). These data highlight the resilience of the cerebral circulation in that dCA was well maintained or improved in healthy pregnant women between TM2 and TM3. However, future work addressing the impact of acute and chronic exercise on dCA in women who are at risk for cardiovascular complications during pregnancy is needed.

The Effects of Physical Activity on Arterial Stiffness during Pregnancy: An Observational Study

The objective of the present study was to investigate the relationship between moderate-to-vigorous physical activity (MVPA) and arterial stiffness in pregnancy. Thirty-nine women participated in this study resulting in 68 measurements in non-pregnant (NP; n=21), first (TM1; n=8), second (TM2; n=20), and third trimesters (TM3; n=19). Compliance, distensibility, elasticity, β-stiffness, and carotid to femoral (central) and carotid to finger (peripheral) pulse wave velocity (PWV) were assessed. MVPA was measured using accelerometry. Multilevel linear regressions adjusted for multiple tests per participant using random effects to generate β coefficients and 95% confidence intervals (CI) were performed. Distensibility, elasticity, β-stiffness, central- and peripheral-PWV did not differ between pregnant and non-pregnant assessments. Carotid artery compliance was higher in TM2 compared to NP. Central PWV (β Coef: -0.14, 95% CI: -0.27, -0.02) decreased from early to mid-pregnancy and increased in late pregnancy. Meeting the MVPA guidelines was significantly associated with central-PWV (Adj. β Coef: -0.34, 95% CI: -0.62, -0.06, p=0.016), peripheral-PWV (Adj. β Coef: -0.54, 95% CI: -0.91, -0.16, p=0.005), and distensibility (Adj. β Coef: -0.001, 95% CI: -0.002, -0.0001, p=0.018), in pregnancy. These results suggest that MVPA may be associated with improved (i.e. reduced) arterial stiffness in pregnancy. Novelty Bullets • Central PWV, distensibility, compliance, elasticity, and ß-stiffness, but not peripheral PWV, exhibited curvilinear relationships with gestational age • Central and peripheral PWV were lower in pregnant women who met the physical activity guidelines of 150 minutes of moderate-to-vigorous physical activity per week.

Effects of prenatal artificial sweeteners consumption on birth outcomes: a systematic review and meta-analysis

OBJECTIVE

To examine the influence of prenatal artificial sweetener (AS) consumption on birth outcomes.

DESIGN

Systematic review and meta-analysis.

SETTING

Online databases (Medline, CINAHL, Embase, Cochrane Library, Scopus, Web of Science, FSTA - the food resource database, and ClinicalTrials.gov) were searched up to 9 April 2020. Studies of all designs (except case studies and reviews) were eligible, which contained information on the relevant population (pregnant women), intervention/exposure (any AS consumption), comparator (no AS consumption) and birth outcomes (preterm delivery, gestational age, birth weight).

RESULTS

From 677 citations, ten cohort studies and one randomised controlled trial (n 138 007 women) were included. 'Low' to 'very low' certainty evidence revealed that daily consumption of AS was associated with an increased risk of preterm delivery (three studies, n 129 009; risk ratio = 1·18, 95 % CI 1·09, 1·28, I2 = 9 %), a 24 g increase in birth weight (three studies, n 64 417; mean difference (MD): 23·74 g, 95 % CI 0·89, 45·58, I2 = 0 %) and a 0·11 week decrease in gestational age (three studies, n 64 417; MD: -0·11 weeks, 95 % CI -0·19, -0·03, I2 = 0 %).

CONCLUSIONS

'Low' to 'very low' certainty evidence suggests daily AS consumption during pregnancy is associated with an increased risk of preterm delivery, increased birth weight and decreased gestational age. Additional 'high'-quality research is urgently needed to further assess these relationships.PROSPERO registration number: CRD42019136728.

The Nine 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, 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 aim of this review is to describe the systemic adaptations that take place in pregnancy. Secondly, this review aims 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.

Blood glucose concentration is unchanged during exposure to acute normobaric hypoxia in healthy humans

Normal blood [glucose] regulation is critical to support metabolism, particularly in contexts of metabolic stressors (e.g., exercise, high altitude hypoxia). Data regarding blood [glucose] regulation in hypoxia are inconclusive. We aimed to characterize blood [glucose] over 80 min following glucose ingestion during both normoxia and acute normobaric hypoxia. In a randomized cross-over design, on two separate days, 28 healthy participants (16 females; 21.8 ± 1.6 years; BMI 22.8 ± 2.5 kg/m2 ) were randomly exposed to either NX (room air; fraction of inspired [FI ]O2 ~0.21) or HX (FI O2 ~0.148) in a normobaric hypoxia chamber. Measured FI O2 and peripheral oxygen saturation were both lower at baseline in hypoxia (p < 0.001), which was maintained over 80 min, confirming the hypoxic intervention. Following a 10-min baseline (BL) under both conditions, participants consumed a standardized glucose beverage (75 g, 296 ml) and blood [glucose] and physiological variables were measured at BL intermittently over 80 min. Blood [glucose] was measured from finger capillary samples via glucometer. Initial fasted blood [glucose] was not different between trials (NX:4.8 ± 0.4 vs. HX:4.9 ± 0.4 mmol/L; p = 0.47). Blood [glucose] was sampled every 10 min (absolute, delta, and percent change) following glucose ingestion over 80 min, and was not different between conditions (p > 0.77). In addition, mean, peak, and time-to-peak responses during the 80 min were not different between conditions (p > 0.14). There were also no sex differences in these blood [glucose] responses in hypoxia. We conclude that glucose regulation is unchanged in young, healthy participants with exposure to acute steady-state normobaric hypoxia, likely due to counterbalancing mechanisms underlying blood [glucose] regulation in hypoxia.

Health Outcomes after Pregnancy in Elite Athletes: A Systematic Review and Meta-analysis

PURPOSE

This study aimed to evaluate postpartum maternal health and training outcomes of females who were competing or training as elite athletes before or during pregnancy.

METHODS

Online databases were searched up to August 26, 2020. Studies of any design and language were eligible if they contained information on the relevant population (postpartum athletes [any period after pregnancy]), exposure (engaged in the highest level of sport immediately before or during pregnancy), comparators (sedentary/active controls), and outcomes: maternal (breastfeeding initiation and duration, postpartum weight retention or loss, bone mineral density, low back or pelvic girdle pain, incontinence [prevalence or severity of stress, urge or mixed urinary incontinence, fecal incontinence], injury, anemia, diastasis recti, breast pain, depression, anxiety) and training (<6 wk time to resume activity, training volume or intensity, performance level).

RESULTS

Eleven studies (n = 482 females, including 372 elite athletes) were included. We identified "very low" certainty evidence demonstrating a higher rate of return to sport before 6 wk postpartum among elite athletes compared with nonelite athletes (n = 145, odds ratio = 6.93, 95% confidence interval = 2.73-17.63, I2 = 11). "Very low" certainty evidence from three studies (n = 179) indicated 14 elite athletes obtained injuries postpartum (7 stress fractures, 9 "running injuries"). "Very low" certainty evidence from five studies (n = 262) reported that 101 (40.5%) elite athletes experienced improved performance postpartum.

CONCLUSION

Compared with controls, "very low" quality evidence suggests that elite athletes return to physical activity early in the postpartum period and may have an increased risk of injury. Additional high-quality evidence is needed to safely guide return to sport of elite athletes in the postpartum period.

Prenatal Exercise and Cardiovascular Health (PEACH) Study: Impact on the Vascular System

PURPOSE

Healthy pregnancy is typically associated with favorable vascular adaptations to both structure and function of the peripheral arteries. Exercise is independently associated with improvements in peripheral vascular health; however, the impact of exercise on prenatal adaptations is unclear. Therefore, we hypothesized that a structured aerobic exercise intervention between the second and third trimester (TM2 and TM3, respectively) of pregnancy would augment the already-positive changes in vascular outcomes.

METHODS

We recruited 59 inactive pregnant women (<20 weeks gestation) and randomized them into control (standard care; n = 28) or exercise (moderate intensity aerobic exercise, 3-4 days/week, 25-40 minutes, 14 ± 1 weeks; n = 31) conditions. Before and after the intervention all women completed comprehensive peripheral vascular assessment, which included blood markers of vascular health, carotid distensibility metrics, measures of arterial stiffness (pulse wave velocity; PWV), and [superficial] femoral artery reactivity during cold pressor test (CPT).

RESULTS

Carotid artery diameter increased from 6.5 mm to 6.9 mm (p < 0.001) strain (%)decreased from 9.9% to 8.4% (p < 0.001). Carotid artery blood flow, compliance and distensibility coefficients, stiffness (β), distensibility (1/β), and Elastic modulus were not different across gestation. PWV was not different across gestation. Superficial femoral artery diameter was increased from 5.4 mm to 5.6 mm (p = 0.004) while blood flow, conductance, and resistance at rest and during CPT were not different across gestation. None of our measures of vascular health were impacted by exercise.

CONCLUSION

We did not observe an impact of aerobic exercise on altering the changes across pregnancy in blood vessel health. However, the present study was conducted in women who were overall at low risk for developing gestational hypertension and should be interpreted with caution. Future work in high-risk women is needed.

Prenatal exercise and cardiovascular health (PEACH) study: The remote effect of aerobic exercise training on conduit artery and resistance vessel function

We assessed the impact of a structured lower-limb aerobic exercise training intervention during pregnancy on brachial artery endothelial function, shear rate and patterns, and forearm blood flow and reactive hyperemia. Twenty-seven pregnant women were recruited and randomized into either a control group (n=11; 31.0 ± 0.7 years), or an exercise intervention group (n=16; 32.6 ± 0.9 years; NCT02948439). The exercise group completed 40 minutes of aerobic exercise (50-70% heart rate reserve) 3-4 times per week, between the second and third trimester of pregnancy. Endothelial function was assessed using flow-mediated dilation (FMD, normalized for shear stress) pre- (16-20 weeks) and post-intervention (34-36 weeks). The exercise training group experienced an attenuated increase in mean arterial pressure (MAP) relative to the control group (∆MAP exercise: +2± 2 mmHg vs. control: +7±3 mmHg; p=0.044) from pre- to post-intervention. % FMD change corrected for shear stress was not different between groups (p=0.460); however, the post occlusion mean flow rate (exercise: 437±32 mL/min vs. control: 364±35 mL/min; p=0.001) and post occlusion anterograde flow rate (exercise: 438±32 mL/min vs. control: 364±46 mL/min;p=0.001) were larger for the exercise training group compared to controls, post-intervention. Although endothelial function was not different between groups, we observed an increase in microcirculatory dilatory capacity, as suggested by the augmented reactive hyperemia in the exercise training group. Novelty: • Endothelial function was not altered with exercise training during pregnancy. • Exercise training did contribute to improved cardiovascular outcomes, which may have been associated with augmented reactive hyperaemia, indicative of increased microcirculatory dilatory capacity.

Cardiac Responses to Prenatal Resistance Exercise with and without the Valsalva Maneuver

PURPOSE

Exercise guidelines recommend incorporating resistance exercise (RE) into a regular aerobic training program during pregnancy. However, few women do so because of uncertainties about the safety of prenatal RE, particularly regarding the Valsalva maneuver (VM). The aim of this study was to determine the acute cardiovascular responses to prenatal RE at different intensities, with and without VM.

METHODS

Healthy pregnant (n = 15; 22.9 ± 5.9 wk of gestation) and nonpregnant women (n = 15) were recruited. Maximal strength over 10 repetitions (10RM) for semireclined leg press was determined. Women underwent standardized assessments of cardiac structure, function and mechanics (echocardiography), heart rate (ECG), and blood pressure (photoplethysmography) at baseline, during RE at 20%, 40%, and 60% 10RM while free-breathing, and at 40% 10RM with VM. Significant differences were identified between subjects at baseline (independent t-tests), between and within subjects during free-breathing RE (general linear model, baseline as a covariate), and between and within subjects for 40% 10RM free-breathing versus VM (mixed-effects model).

RESULTS

Resting cardiac output, heart rate, and stroke volume were greater in pregnant women, without differences in blood pressure, ejection fraction, or cardiac mechanics. During free-breathing RE, pregnant women had a greater ejection fraction compared with nonpregnant women; however, all other hemodynamic variables were not different between groups. Cardiac mechanics during free-breathing RE across all intensities were not different between groups, with the exception that pregnant women had a lower apical circumferential strain that did not affect global cardiac function. No differences were observed between groups during 40% 10RM RE with and without VM.

CONCLUSIONS

Pregnant women have proportionate cardiac responses to light-moderate RE, both with and without the VM. These findings reinforce the safety of RE in healthy pregnancy.

Prenatal Exercise and Cardiovascular Health (PEACH) Study: Impact on Muscle Sympathetic Nerve (Re)Activity

PURPOSE

Women who develop gestational hypertension have evidence of elevated muscle sympathetic nerve activity (MSNA) in early pregnancy, which continues to rise after diagnosis. Exercise has been shown to play a preventative role in the development of gestational hypertension and has been shown to reduce resting and reflex MSNA in nonpregnant populations. We sought to investigate whether aerobic exercise affected the sympathetic regulation of blood pressure between the second and third trimesters of pregnancy.

METHODS

We conducted a randomized controlled trial of structured aerobic exercise (n = 31) compared with no intervention (control, n = 28) beginning at 16-20 wk and continuing until 34-36 wk of gestation (NCT02948439). Women in the exercise group were prescribed aerobic activity at 50%-70% of their heart rate reserve, on 3-4 d·wk-1 for 25-40 min with a 5-min warm-up and 5-min cool-down (i.e., up to 160 min total activity per week). At preintervention and postintervention assessments, data from ~10 min of quiet rest and a 3-min cold pressor test were analyzed to determine sympathetic nervous system activity and reactivity.

RESULTS

MSNA was obtained in 51% of assessments. Resting MSNA burst frequency and burst incidence increased across gestation (main effect of gestational age, P = 0.002). Neurovascular transduction was blunted in the control group (P = 0.024) but not in exercisers (P = 0.873) at the postintervention time point. Lastly, MSNA reactivity during the cold pressor test was not affected by gestational age or exercise (P = 0.790, interaction).

CONCLUSIONS

These data show that exercise attenuates both the rise in MSNA and the blunting of neurovascular transduction. This may partially explain the lower risk of developing gestational hypertension in women who are active during their pregnancies.

Leisure-Time Physical Activity before and during Pregnancy Is Associated with Improved Insulin Resistance in Late Pregnancy

A total of 83 third trimester pregnant women were recruited to examine the role of pre-pregnancy versus late-pregnancy physical activity on maternal insulin resistance. Principal component analysis plots demonstrated a distinction between the high and low Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) groups. The variation was driven primarily by exercise prior to and during pregnancy. Specifically, higher levels of physical activity prior to pregnancy was associated with a lower HOMA-IR and is not modified by other variables. Women who were active prior to pregnancy were more active during pregnancy. These results suggest that being active before pregnancy may be a good strategy for mitigating the risk of insulin resistance during late pregnancy.

Physical Activity Behaviors and Barriers in Multifetal Pregnancy: What to Expect When You're Expecting More

The health benefits of prenatal physical activity (PA) are established for singleton pregnancies. In contrast, individuals with multifetal pregnancies (twins, triplets or more) are recommended to restrict or cease PA. The objectives of the current study were to determine behaviors and barriers to PA in multifetal pregnancies. Between 29 May and 24 July 2020, individuals with multifetal pregnancies participated in an online survey. Of the 415 respondents, there were 366 (88%) twin, 45 (11%) triplet and 4 (1%) quadruplet pregnancies. Twenty-seven percent (n = 104/388) of respondents completed no PA at all during pregnancy, 57% (n = 220/388) completed PA below current recommendations, and 16% (n = 64/388) achieved current recommendations (150-min per week of moderate-intensity activity). Most respondents (n = 314/363 [87%]) perceived barriers to PA during multifetal pregnancy. The most prominent were physical symptoms (n = 204/363 [56%]) and concerns about risks to fetal wellbeing (n = 128/363 [35%]). Sixty percent (n = 92/153) felt that these barriers could be overcome but expressed the need for evidence-based information regarding PA in multifetal pregnancy. Individuals with multifetal pregnancies have low engagement with current PA recommendations but remain physically active in some capacity. There are physical and psychosocial barriers to PA in multifetal pregnancy and future research should focus on how these can be removed.

Elite Athletes and Pregnancy Outcomes: A Systematic Review and Meta-analysis

PURPOSE

The purpose of this systematic review was to evaluate fetal and maternal pregnancy outcomes of elite athletes who had participated in competitive sport immediately before conception.

METHODS

Online databases were searched up to March 24, 2020. Studies of any design and language were eligible if they contained information on the relevant population (pregnant women), exposure (engaged in elite sport immediately before pregnancy), and outcomes (birth weight, low birth weight, macrosomia, preterm birth, fetal heart rate and pulse index, cesarean sections, instrumental deliveries, episiotomies, duration of labor, perineal tears, pregnancy-induced low back pain, pelvic girdle pain, urinary incontinence, miscarriages, prenatal weight gain, inadequate/excess prenatal weight gain, maternal depression or anxiety).

RESULTS

Eleven unique studies (n = 2256 women) were included. We identified "low" certainty evidence demonstrating lower rates of low back pain in elite athletes compared with active/sedentary controls (n = 248; odds ratio, 0.38; 95% confidence interval, 0.20-0.73; I2 = 0%) and "very low" certainty evidence indicating an increased odds of excessive prenatal weight gain in elite athletes versus active/sedentary controls (n = 1763; odds ratio, 2.47; 95% confidence interval, 1.26-4.85; I2 = 0%). Low certainty evidence from two studies (n = 7) indicated three episodes of fetal bradycardia after high-intensity exercise that resolved within 10 min of cessation of activity. No studies reported inadequate gestational weight gain or maternal depression or anxiety. There were no differences between elite athletes and controls for all other outcomes.

CONCLUSIONS

There is "low" certainty of evidence that elite athletes have reduced odds of experiencing pregnancy-related low back pain and "very low"certainty of evidence that elite athletes have increased the odds of excessive weight gain compared with active/sedentary controls. More research is needed to provide strong evidence of how elite competitive sport before pregnancy affects maternal and fetal outcomes.PROSPERO Registration: CRD42020167382.

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.

Cardiovascular function during triplet pregnancy

Pregnancy is recognized as a natural physiological stressor to the maternal cardiovascular system. Cardiovascular adaptation is markedly greater in twin pregnancy compared with singleton pregnancy; however, these changes are sparsely documented in triplet pregnancy. The aim of this case series was to compare maternal cardiac function, cardioautonomic regulation, and blood pressure reactivity in healthy singleton, twin, and triplet pregnancies. Resting cardiac structure and function (echocardiography), beat-by-beat blood pressure variability (BPV; photoplethysmography), and heart rate variability (HRV; electrocardiogram) were measured in two triplet, three twin, and three singleton pregnancies (matched for maternal age, prepregnancy body mass index, and gestational age). Hemodynamic responses to a 3-min cold pressor test were also recorded to assess blood pressure reactivity. Due to the small sample size of this case series, statistical comparisons were not made between groups. Compared with singleton and twin pregnancies, individuals pregnant with triplets had greater resting cardiac output but lower cardiac deformation (longitudinal strain, basal circumferential strain, and torsion), sympathetic dominance in cardioautonomic regulation (lower HRV and higher BPV), and elevated blood pressure reactivity in response to the cold pressor test. Taken together, these observations suggest that females with triplet pregnancies may have reduced cardiovascular function, which may contribute to the heightened risk of complications in multifetal pregnancies.NEW & NOTEWORTHY Individuals with healthy triplet pregnancies had greater resting cardiac output but lower left ventricular mechanics when compared with singleton and twin pregnancies matched for gestational age. In addition, triplet pregnancies had greater blood pressure variability and lower overall heart rate variability compared with singleton pregnancies, as well as greater blood pressure reactivity to the cold pressor test. Healthy triplet pregnancies may have reduced cardiovascular function as well as a greater sympathetic contribution to cardiac control.