Effects of prenatal exercise on fetal heart rate, umbilical and uterine blood flow: a systematic review and meta-analysis.

OBJECTIVE: To perform a systematic review and meta-analysis examining the influence of acute and chronic prenatal exercise on fetal heart rate (FHR) and umbilical and uterine blood flow metrics. DESIGN: Systematic review with random-effects meta-analysis and meta-regression. DATA SOURCES: Online databases were searched up to 6 January 2017. STUDY ELIGIBILITY CRITERIA: Studies of all designs were included (except case studies) if published in English, Spanish or French, and contained information on the population (pregnant women without contraindication to exercise), intervention (subjective or objective measures of frequency, intensity, duration, volume or type of exercise, alone ["exercise-only"] or in combination with other intervention components [eg, dietary; "exercise + co-intervention"]), comparator (no exercise or different frequency, intensity, duration, volume and type of exercise) and outcomes (FHR, beats per minute (bpm); uterine and umbilical blood flow metrics (systolic:diastolic (S/D) ratio; Pulsatility Index (PI); Resistance Index (RI); blood flow, mL/min; and blood velocity, cm/s)). RESULTS: 'Very low' to 'moderate' quality evidence from 91 unique studies (n=4641 women) were included. Overall, FHR increased during (mean difference (MD)=6.35bpm; 95% CI 2.30 to 10.41, I2=95%, p=0.002) and following acute exercise (MD=4.05; 95% CI 2.98 to 5.12, I2=83%, p<0.00001). The incidence of fetal bradycardia was low at rest and unchanged with acute exercise. There were no significant changes in umbilical or uterine S/D, PI, RI, blood flow or blood velocity during or following acute exercise sessions. Chronic exercise decreased resting FHR and the umbilical artery S/D, PI and RI at rest. CONCLUSION: Acute and chronic prenatal exercise do not adversely impact FHR or uteroplacental blood flow metrics.

Is supine exercise associated with adverse maternal and fetal outcomes? A systematic review.

OBJECTIVE: Theoretical concerns regarding the supine position at rest due to the gravid uterus obstructing aorta and vena caval flow may impinge uterine blood flow (UBF) to the fetus and maternal venous return. DESIGN: Systematic review. DATA SOURCES: Online databases up to 11 December 2017. STUDY CRITERIA: Eligible population (pregnant without contraindication to exercise), intervention (frequency, intensity, duration, volume or type of supine exercise), comparator (no exercise or exercise in left lateral rest position, upright posture or other supine exercise), outcomes (potentially adverse effects on maternal blood pressure, cardiac output, heart rate, oxygen saturation, fetal movements, UBF, fetal heart rate (FHR) patterns; adverse events such as bradycardia, low birth weight, intrauterine growth restriction, perinatal mortality and other adverse events as documented by study authors), and study design (except case studies and reviews) published in English, Spanish, French or Portuguese. RESULTS: Seven studies (n=1759) were included. 'Very low' to 'low' quality evidence from three randomised controlled trials indicated no association between supervised exercise interventions that included supine exercise and low birth weight compared with no exercise. There was 'very low' to 'low' quality evidence from four observational studies that showed no adverse events in the mother; however, there were abnormal FHR patterns (as defined by study authors) in 20 of 65 (31%) fetuses during an acute bout of supine exercise. UBF decreased (13%) when women moved from left lateral rest to acute dynamic supine exercise. CONCLUSION: There was insufficient evidence to ascertain whether maternal exercise in the supine position is safe or should be avoided during pregnancy.

Exercise for the prevention and treatment of low back, pelvic girdle and lumbopelvic pain during pregnancy: a systematic review and meta-analysis.

OBJECTIVE: The purpose of this review was to investigate the relationship between prenatal exercise, and low back (LBP), pelvic girdle (PGP) and lumbopelvic (LBPP) pain. DESIGN: Systematic review with random effects meta-analysis and meta-regression. DATA SOURCES: Online databases were searched up to 6 January 2017. STUDY ELIGIBILITY CRITERIA: Studies of all designs were eligible (except case studies and reviews) if they were published in English, Spanish or French, and contained information on the population (pregnant women without contraindication to exercise), intervention (subjective or objective measures of frequency, intensity, duration, volume or type of exercise, alone ["exercise-only"] or in combination with other intervention components [eg, dietary; "exercise + co-intervention"]), comparator (no exercise or different frequency, intensity, duration, volume and type of exercise) and outcome (prevalence and symptom severity of LBP, PGP and LBPP). RESULTS: The analyses included data from 32 studies (n=52 297 pregnant women). 'Very low' to 'moderate' quality evidence from 13 randomised controlled trials (RCTs) showed prenatal exercise did not reduce the odds of suffering from LBP, PGP and LBPP either in pregnancy or the postpartum period. However, 'very low' to 'moderate' quality evidence from 15 RCTs identified lower pain severity during pregnancy and the early postpartum period in women who exercised during pregnancy (standardised mean difference -1.03, 95% CI -1.58, -0.48) compared with those who did not exercise. These findings were supported by 'very low' quality evidence from other study designs. CONCLUSION: Compared with not exercising, prenatal exercise decreased the severity of LBP, PGP or LBPP during and following pregnancy but did not decrease the odds of any of these conditions at any time point.

Prenatal exercise is not associated with fetal mortality: a systematic review and meta-analysis.

OBJECTIVE: To perform a systematic review of the relationship between prenatal exercise and fetal or newborn death. DESIGN: Systematic review with random-effects meta-analysis and meta-regression. DATA SOURCES: Online databases were searched up to 6 January 2017. STUDY ELIGIBILITY CRITERIA: Studies of all designs were included (except case studies) if they were published in English, Spanish or French and contained information on the population (pregnant women without contraindication to exercise), intervention (subjective or objective measures of frequency, intensity, duration, volume or type of exercise, alone ["exercise-only"] or in combination with other intervention components [eg, dietary; "exercise + co-intervention"]), comparator (no exercise or different frequency, intensity, duration, volume and type of exercise) and outcome (miscarriage or perinatal mortality). RESULTS: Forty-six studies (n=2 66 778) were included. There was 'very low' quality evidence suggesting no increased odds of miscarriage (23 studies, n=7125 women; OR 0.88, 95% CI 0.63 to 1.21, I2=0%) or perinatal mortality (13 studies, n=6837 women, OR 0.86, 95% CI 0.49 to 1.52, I2=0%) in pregnant women who exercised compared with those who did not. Stratification by subgroups did not affect odds of miscarriage or perinatal mortality. The meta-regressions identified no associations between volume, intensity or frequency of exercise and fetal or newborn death. As the majority of included studies examined the impact of moderate intensity exercise to a maximum duration of 60 min, we cannot comment on the effect of longer periods of exercise. SUMMARY/CONCLUSIONS: Although the evidence in this field is of 'very low' quality, it suggests that prenatal exercise is not associated with increased odds of miscarriage or perinatal mortality. In plain terms, this suggests that generally speaking exercise is 'safe' with respect to miscarriage and perinatal mortality.

Effects of prenatal exercise on incidence of congenital anomalies and hyperthermia: a systematic review and meta-analysis.

OBJECTIVE: To investigate the relationships between exercise and incidence of congenital anomalies and hyperthermia. DESIGN: Systematic review with random-effects meta-analysis . DATA SOURCES: Online databases were searched from inception up to 6 January 2017. STUDY ELIGIBILITY CRITERIA: Studies of all designs were eligible (except case studies and reviews) if they were published in English, Spanish or French, and contained information on population (pregnant women without contraindication to exercise), intervention (subjective or objective measures of frequency, intensity, duration, volume or type of exercise, alone ["exercise-only"] or in combination with other intervention components [e.g., dietary; "exercise + co-intervention"]), comparator (no exercise or different frequency, intensity, duration, volume or type of exercise) and outcome (maternal temperature and fetal anomalies). RESULTS: This systematic review and meta-analysis included 'very low' quality evidence from 14 studies (n=78 735) reporting on prenatal exercise and the odds of congenital anomalies, and 'very low' to 'low' quality evidence from 15 studies (n=447) reporting on maternal temperature response to prenatal exercise. Prenatal exercise did not increase the odds of congenital anomalies (OR 1.23, 95% CI 0.77 to 1.95, I2=0%). A small but significant increase in maternal temperature was observed from pre-exercise to both during and immediately after exercise (during: 0.26°C, 95% CI 0.12 to 0.40, I2=70%; following: 0.24°C, 95% CI 0.17 to 0.31, I2=47%). SUMMARY/CONCLUSIONS: These data suggest that moderate-to-vigorous prenatal exercise does not induce hyperthermia or increase the odds of congenital anomalies. However, exercise responses were investigated in most studies after 12 weeks' gestation when the risk of de novo congenital anomalies is negligible.

Impact of prenatal exercise on maternal harms, labour and delivery outcomes: a systematic review and meta-analysis.

OBJECTIVE: To perform a systematic review of the relationships between prenatal exercise and maternal harms including labour/delivery outcomes. DESIGN: Systematic review with random effects meta-analysis and meta-regression. DATASOURCES: Online databases were searched up to 6 January 2017. STUDY ELIGIBILITY CRITERIA: Studies of all designs were included (except case studies) if they were published in English, Spanish or French and contained information on the population (pregnant women without contraindication to exercise), intervention (subjective or objective measures of frequency, intensity, duration, volume or type of exercise), comparator (no exercise or different frequency, intensity, duration, volume and type of exercise, alone ["exercise-only"] or in combination with other intervention components [e.g., dietary; "exercise + co-intervention"]) and outcome (preterm/prelabour rupture of membranes, caesarean section, instrumental delivery, induction of labour, length of labour, vaginal tears, fatigue, injury, musculoskeletal trauma, maternal harms (author defined) and diastasis recti). RESULTS: 113 studies (n=52 858 women) were included. 'Moderate' quality evidence from exercise-only randomised controlled trials (RCTs) indicated a 24% reduction in the odds of instrumental delivery in women who exercised compared with women who did not (20 RCTs, n=3819; OR 0.76, 95% CI 0.63 to 0.92, I 2= 0 %). The remaining outcomes were not associated with exercise. Results from meta-regression did not identify a dose-response relationship between frequency, intensity, duration or volume of exercise and labour and delivery outcomes. SUMMARY/CONCLUSIONS: Prenatal exercise reduced the odds of instrumental delivery in the general obstetrical population. There was no relationship between prenatal exercise and preterm/prelabour rupture of membranes, caesarean section, induction of labour, length of labour, vaginal tears, fatigue, injury, musculoskeletal trauma, maternal harms and diastasis recti.

2019 Canadian guideline for physical activity throughout pregnancy.

The objective is to provide guidance for pregnant women and obstetric care and exercise professionals on prenatal physical activity. The outcomes evaluated were maternal, fetal or neonatal morbidity, or fetal mortality during and following pregnancy. Literature was retrieved through searches of MEDLINE, EMBASE, PsycINFO, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, Scopus and Web of Science Core Collection, CINAHL Plus with Full Text, Child Development & Adolescent Studies, Education Resources Information Center, SPORTDiscus, ClinicalTrials.gov and the Trip Database from inception up to 6 January 2017. Primary studies of any design were eligible, except case studies. Results were limited to English-language, Spanish-language or French-language materials. Articles related to maternal physical activity during pregnancy reporting on maternal, fetal or neonatal morbidity, or fetal mortality were eligible for inclusion. The quality of evidence was rated using the Grading of Recommendations Assessment, Development and Evaluation methodology. The Guidelines Consensus Panel solicited feedback from end users (obstetric care providers, exercise professionals, researchers, policy organisations, and pregnant and postpartum women). The development of these guidelines followed the Appraisal of Guidelines for Research and Evaluation II instrument. The benefits of prenatal physical activity are moderate and no harms were identified; therefore, the difference between desirable and undesirable consequences (net benefit) is expected to be moderate. The majority of stakeholders and end users indicated that following these recommendations would be feasible, acceptable and equitable. Following these recommendations is likely to require minimal resources from both individual and health systems perspectives.

Effectiveness of exercise interventions in the prevention of excessive gestational weight gain and postpartum weight retention: a systematic review and meta-analysis.

OBJECTIVE: Gestational weight gain (GWG) has been identified as a critical modifier of maternal and fetal health. This systematic review and meta-analysis aimed to examine the relationship between prenatal exercise, GWG and postpartum weight retention (PPWR). DESIGN: Systematic review with random effects meta-analysis and meta-regression. Online databases were searched up to 6 January 2017. STUDY ELIGIBILITY CRITERIA: Studies of all designs in English, Spanish or French were eligible (except case studies and reviews) if they contained information on the population (pregnant women without contraindication to exercise), intervention (frequency, intensity, duration, volume or type of exercise, alone ["exercise-only"] or in combination with other intervention components [eg, dietary; "exercise + co-intervention"]), comparator (no exercise or different frequency, intensity, duration, volume or type of exercise) and outcomes (GWG, excessive GWG (EGWG), inadequate GWG (IGWG) or PPWR). RESULTS: Eighty-four unique studies (n=21 530) were included. 'Low' to 'moderate' quality evidence from randomised controlled trials (RCTs) showed that exercise-only interventions decreased total GWG (n=5819; -0.9 kg, 95% CI -1.23 to -0.57 kg, I2=52%) and PPWR (n=420; -0.92 kg, 95% CI -1.84 to 0.00 kg, I2=0%) and reduced the odds of EGWG (n=3519; OR 0.68, 95% CI 0.57 to 0.80, I2=12%) compared with no exercise. 'High' quality evidence indicated higher odds of IGWG with prenatal exercise-only (n=1628; OR 1.32, 95% CI 1.04 to 1.67, I2=0%) compared with no exercise. CONCLUSIONS: Prenatal exercise reduced the odds of EGWG and PPWR but increased the risk of IGWG. However, the latter result should be interpreted with caution because it was based on a limited number of studies (five RCTs).

Prenatal exercise for the prevention of gestational diabetes mellitus and hypertensive disorders of pregnancy: a systematic review and meta-analysis.

OBJECTIVE: Gestational diabetes mellitus (GDM), gestational hypertension (GH) and pre-eclampsia (PE) are associated with short and long-term health issues for mother and child; prevention of these complications is critically important. This study aimed to perform a systematic review and meta-analysis of the relationships between prenatal exercise and GDM, GH and PE. DESIGN: Systematic review with random effects meta-analysis and meta-regression. DATA SOURCES: Online databases were searched up to 6 January 2017. STUDY ELIGIBILITY CRITERIA: Studies of all designs were included (except case studies) if published in English, Spanish or French, and contained information on the Population (pregnant women without contraindication to exercise), Intervention (subjective or objective measures of frequency, intensity, duration, volume or type of exercise, alone ["exercise-only"] or in combination with other intervention components [e.g., dietary; "exercise + co-intervention"]), Comparator (no exercise or different frequency, intensity, duration, volume and type of exercise) and Outcomes (GDM, GH, PE). RESULTS: A total of 106 studies (n=273 182) were included. 'Moderate' to 'high'-quality evidence from randomised controlled trials revealed that exercise-only interventions, but not exercise+cointerventions, reduced odds of GDM (n=6934; OR 0.62, 95% CI 0.52 to 0.75), GH (n=5316; OR 0.61, 95% CI 0.43 to 0.85) and PE (n=3322; OR 0.59, 95% CI 0.37 to 0.9) compared with no exercise. To achieve at least a 25% reduction in the odds of developing GDM, PE and GH, pregnant women need to accumulate at least 600 MET-min/week of moderate-intensity exercise (eg, 140 min of brisk walking, water aerobics, stationary cycling or resistance training). SUMMARY/CONCLUSIONS: In conclusion, exercise-only interventions were effective at lowering the odds of developing GDM, GH and PE.

Glucose responses to acute and chronic exercise during pregnancy: a systematic review and meta-analysis.

OBJECTIVE: To perform a systematic review and meta-analysis to explore the relationship between prenatal exercise and glycaemic control. DESIGN: Systematic review with random-effects meta-analysis and meta-regression. DATA SOURCES: Online databases were searched up to 6 January 2017. STUDY ELIGIBILITY CRITERIA: Studies of all designs were included (except case studies and reviews) if they were published in English, Spanish or French, and contained information on the population (pregnant women without contraindication to exercise), intervention (subjective or objective measures of frequency, intensity, duration, volume or type of acute or chronic exercise, alone ('exercise-only') or in combination with other intervention components (eg, dietary; 'exercise+cointervention') at any stage of pregnancy), comparator (no exercise or different frequency, intensity, duration, volume and type of exercise) and outcome (glycaemic control). RESULTS: A total of 58 studies (n=8699) were included. There was 'very low' quality evidence showing that an acute bout of exercise was associated with a decrease in maternal blood glucose from before to during exercise (6 studies, n=123; mean difference (MD) -0.94 mmol/L, 95% CI -1.18 to -0.70, I2=41%) and following exercise (n=333; MD -0.57 mmol/L, 95% CI -0.72 to -0.41, I2=72%). Subgroup analysis showed that there were larger decreases in blood glucose following acute exercise in women with diabetes (n=26; MD -1.42, 95% CI -1.69 to -1.16, I2=8%) compared with those without diabetes (n=285; MD -0.46, 95% CI -0.60 to -0.32, I2=62%). Finally, chronic exercise-only interventions reduced fasting blood glucose compared with no exercise postintervention in women with diabetes (2 studies, n=70; MD -2.76, 95% CI -3.18 to -2.34, I2=52%; 'low' quality of evidence), but not in those without diabetes (9 studies, n=2174; MD -0.05, 95% CI -0.16 to 0.05, I2=79%). CONCLUSION: Acute and chronic prenatal exercise reduced maternal circulating blood glucose concentrations, with a larger effect in women with diabetes.

Impact of prenatal exercise on both prenatal and postnatal anxiety and depressive symptoms: a systematic review and meta-analysis.

OBJECTIVE: To examine the influence of prenatal exercise on depression and anxiety during pregnancy and the postpartum period. DESIGN: Systematic review with random effects meta-analysis and meta-regression. DATA SOURCES: Online databases were searched up to 6 January 2017. STUDY ELIGIBILITY CRITERIA: Studies of all designs were included (except case studies) if they were published in English, Spanish or French and contained information on the Population (pregnant women without contraindication to exercise), Intervention (subjective or objective measures of frequency, intensity, duration, volume or type of exercise), Comparator (no exercise or different frequency, intensity, duration, volume and type of exercise) and Outcome (prenatal or postnatal depression or anxiety). RESULTS: A total of 52 studies (n=131 406) were included. 'Moderate' quality evidence from randomised controlled trials (RCTs) revealed that exercise-only interventions, but not exercise+cointerventions, reduced the severity of prenatal depressive symptoms (13 RCTs, n=1076; standardised mean difference: -0.38, 95% CI -0.51 to -0.25, I2=10%) and the odds of prenatal depression by 67% (5 RCTs, n=683; OR: 0.33, 95% CI 0.21 to 0.53, I2=0%) compared with no exercise. Prenatal exercise did not alter the odds of postpartum depression or the severity of depressive symptoms, nor anxiety or anxiety symptoms during or following pregnancy. To achieve at least a moderate effect size in the reduction of the severity of prenatal depressive symptoms, pregnant women needed to accumulate at least 644 MET-min/week of exercise (eg, 150 min of moderate intensity exercise, such as brisk walking, water aerobics, stationary cycling, resistance training). SUMMARY/CONCLUSIONS: Prenatal exercise reduced the odds and severity of prenatal depression.

Impact of prenatal exercise on neonatal and childhood outcomes: a systematic review and meta-analysis.

OBJECTIVE: We aimed to identify the relationship between maternal prenatal exercise and birth complications, and neonatal and childhood morphometric, metabolic and developmental outcomes. DESIGN: Systematic review with random-effects meta-analysis and meta-regression. DATA SOURCES: Online databases were searched up to 6 January 2017. STUDY ELIGIBILITY CRITERIA: Studies of all designs were eligible (except case studies and reviews) if published in English, Spanish or French, and contained information on the relevant population (pregnant women without contraindication to exercise), intervention (subjective/objective measures of frequency, intensity, duration, volume or type of exercise, alone ('exercise-only') or in combination with other intervention components (eg, dietary; 'exercise+cointervention')), comparator (no exercise or different frequency, intensity, duration, volume, type or trimester of exercise) and outcomes (preterm birth, gestational age at delivery, birth weight, low birth weight (<2500 g), high birth weight (>4000 g), small for gestational age, large for gestational age, intrauterine growth restriction, neonatal hypoglycaemia, metabolic acidosis (cord blood pH, base excess), hyperbilirubinaemia, Apgar scores, neonatal intensive care unit admittance, shoulder dystocia, brachial plexus injury, neonatal body composition (per cent body fat, body weight, body mass index (BMI), ponderal index), childhood obesity (per cent body fat, body weight, BMI) and developmental milestones (including cognitive, psychosocial, motor skills)). RESULTS: A total of 135 studies (n=166 094) were included. There was 'high' quality evidence from exercise-only randomised controlled trials (RCTs) showing a 39% reduction in the odds of having a baby >4000 g (macrosomia: 15 RCTs, n=3670; OR 0.61, 95% CI 0.41 to 0.92) in women who exercised compared with women who did not exercise, without affecting the odds of growth-restricted, preterm or low birth weight babies. Prenatal exercise was not associated with the other neonatal or infant outcomes that were examined. CONCLUSIONS: Prenatal exercise is safe and beneficial for the fetus. Maternal exercise was associated with reduced odds of macrosomia (abnormally large babies) and was not associated with neonatal complications or adverse childhood outcomes.

Prenatal exercise (including but not limited to pelvic floor muscle training) and urinary incontinence during and following pregnancy: a systematic review and meta-analysis.

OBJECTIVE: To examine the relationships between prenatal physical activity and prenatal and postnatal urinary incontinence (UI). DESIGN: Systematic review with random effects meta-analysis and meta-regression. DATA SOURCES: Online databases were searched up to 6 January 2017. STUDY ELIGIBILITY CRITERIA: Studies of all designs were included (except case studies) if they were published in English, Spanish or French and contained information on the Population (pregnant women without contraindication to exercise), Intervention (subjective or objective measures of frequency, intensity, duration, volume or type of exercise, alone ["exercise-only"] or in combination with other intervention components [e.g., dietary; "exercise + co-intervention"]), Comparator (no exercise or different frequency, intensity, duration, volume and type of exercise) and Outcome (prenatal or postnatal UI). RESULTS: 24 studies (n=15 982 women) were included. 'Low' to 'moderate' quality evidence revealed prenatal pelvic floor muscle training (PFMT) with or without aerobic exercise decreased the odds of UI in pregnancy (15 randomised controlled trials (RCTs), n=2764 women; OR 0.50, 95% CI 0.37 to 0.68, I2=60%) and in the postpartum period (10 RCTs, n=1682 women; OR 0.63, 95% CI 0.51, 0.79, I2=0%). When we analysed the data by whether women were continent or incontinent prior to the intervention, exercise was beneficial at preventing the development of UI in women with continence, but not effective in treating UI in women with incontinence. There was 'low' quality evidence that prenatal exercise had a moderate effect in the reduction of UI symptom severity during (five RCTs, standard mean difference (SMD) -0.54, 95% CI -0.88 to -0.20, I2=64%) and following pregnancy (three RCTs, 'moderate' quality evidence; SMD -0.54, 95% CI -0.87 to -0.22, I2=24%). CONCLUSION: Prenatal exercise including PFMT reduced the odds and symptom severity of prenatal and postnatal UI. This was the case for women who were continent before the intervention. Among women who were incontinent during pregnancy, exercise training was not therapeutic.

Characteristics and effectiveness of vasodilatory and pressor compensation for reduced relaxation time during rhythmic forearm contractions.

NEW FINDINGS: What is the central question of this study? Reduced relaxation time between contractions in exercise requires increased vasodilatation and/or pressor response to prevent hypoperfusion and potential compromise to exercise tolerance. However, it remains unknown whether and to what extent local vasodilatation and/or systemic pressor compensation occurs and whether the efficacy of compensation is exercise intensity dependent. What is the main finding and its importance? We demonstrate that in a forearm exercise model vasodilatory but not pressor compensation occurs and is adequate to prevent hypoperfusion below but not above ∼40% peak work rate. Inadequate compensation occurs with exercise still well inside the submaximal domain, despite a vasodilatory reserve, and compromises exercise performance. During muscle contraction in rhythmic exercise, muscle blood flow is significantly impeded by microvascular compression. The purpose of this study was to establish the nature and magnitude of vasodilatory and/or pressor compensatory responses during forearm exercise in the face of an increased duration of mechanical microvascular compression, and whether the effectiveness of such compensation was exercise intensity dependent. Seven healthy males (21.0 ± 1.8 years old) completed progressive forearm exercise (24.5 N every 3 min; 2 s contraction-4 s relaxation duty cycle) in two conditions: control (CON), 2 s 100 mmHg forearm cuff inflation during contraction; and impedance (IMP), extension of cuff inflation 2 s beyond contraction. Forearm blood flow (in millilitres per minute); brachial artery Doppler and echo ultrasound), mean arterial blood pressure (in millimetres of mercury; finger photoplethysmography) and exercising forearm venous effluent (antecubital vein catheter) measurements revealed an exercise intensity-dependent compensatory vasodilatation effectiveness whereby increased vasodilatation fully protected forearm blood flow up to the 30% exercise intensity in IMP. Above this exercise intensity, forearm blood flow was defended only in part, although submaximal oxygen uptake was not compromised for any completed work rate. As a result, peak exercise intensity (175 ± 22 versus 196 ± 28 N, P = 0.04) and oxygen delivery (76 ± 14 versus 112 ± 22 ml O2  min-1 , P = 0.01) were significantly reduced in IMP compared with CON. In conclusion, reducing relaxation time compromised exercise capacity without compromise to oxygen uptake. Vasodilatory compensation was complete at lower but not higher exercise intensities, whereas pressor compensation was absent. The reasons for the exercise intensity dependence of the efficacy of vasodilatory compensation remain to be determined.

Systematic review of the relationships between combinations of movement behaviours and health indicators in the early years (0-4 years).

BACKGROUND: A recent review highlighted important relationships between combinations of movement behaviours (i.e., sleep, sedentary behaviour, and physical activity) and health indicators among school-aged children and youth (aged 5-17 years). It is unclear whether similar relationships exist in younger children. Therefore, this review sought to examine the relationships between combinations of movement behaviours and health indicators in the early years (1.00 month to 4.99 years). METHODS: Medline, EMBASE, PsycINFO, and SportDiscus were searched for relevant studies up to November 2016, with no date or study design limits. Included studies met the a priori-determined population (apparently healthy children aged 1.00 month to 4.99 years), intervention (combination of ≥2 movement behaviours [i.e., sleep and sedentary behaviour; sleep and physical activity; sedentary behaviour and physical activity; and sleep, sedentary behaviour, and physical activity]), comparator (various levels and combinations of movement behaviours), and health outcome/indicator (Critical: adiposity, motor development, psychosocial health/emotional regulation, cognitive development, fitness, and growth; Important: bone and skeletal health, cardiometabolic health, and risks). For each health indicator, quality of evidence was assessed by study design using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) framework. RESULTS: Ten articles (n = 7436 participants; n = 5 countries) were included. Across observational and experimental study designs, the most ideal combinations of sedentary behaviour and physical activity were: favourably associated with motor development and fitness among preschool-aged children (3.00 to 4.99 years); both favourably and not associated with adiposity among toddlers (1.10 to 2.99 years) and preschool-aged children; and not associated with growth among toddlers and preschool-aged children. The most ideal combinations of sleep and sedentary behaviour were favourably associated with adiposity among infants (1.00 month to 1.00 years) and toddlers. Quality of evidence ranged from "very low" to "moderate". CONCLUSIONS: The most ideal combinations of movement behaviours (e.g., high sleep, low sedentary behaviour, high physical activity) may be important for optimal health in the early years. Findings can help inform movement behaviour guidelines for the early years. Given the limited evidence, future research is needed to determine the ideal distribution of daily movement behaviours for optimal health throughout the early years.

Systematic review of the relationships between sleep duration and health indicators in the early years (0-4 years).

BACKGROUND: The objective of this systematic review was to examine for the first time the associations between sleep duration and a broad range of health indicators in children aged 0 to 4 years. METHODS: Electronic databases were searched with no limits on date or study design. Included studies (published in English or French) were peer-reviewed and met the a priori determined population (apparently healthy children aged 1 month to 4.99 years), intervention/exposure/comparator (various sleep durations), and outcome criteria (adiposity, emotional regulation, cognitive development, motor development, growth, cardiometabolic health, sedentary behaviour, physical activity, quality of life/well-being, and risks/injuries). The quality of evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework. Due to high levels of heterogeneity across studies, narrative syntheses were employed. RESULTS: A total of 69 articles/studies (62 unique samples) met inclusion criteria. Data across studies included 148,524 unique participants from 23 countries. The study designs were randomized trials (n = 3), non-randomized interventions (n = 1), longitudinal studies (n = 16), cross-sectional studies (n = 42), or longitudinal studies that also reported cross-sectional analyses (n = 7). Sleep duration was assessed by parental report in 70% of studies (n = 48) and was measured objectively (or both objectively and subjectively) in 30% of studies (n = 21). Overall, shorter sleep duration was associated with higher adiposity (20/31 studies), poorer emotional regulation (13/25 studies), impaired growth (2/2 studies), more screen time (5/5 studies), and higher risk of injuries (2/3 studies). The evidence related to cognitive development, motor development, physical activity, and quality of life/well-being was less clear, with no indicator showing consistent associations. No studies examined the association between sleep duration and cardiometabolic biomarkers in children aged 0 to 4 years. The quality of evidence ranged from "very low" to "high" across study designs and health indicators. CONCLUSIONS: Despite important limitations in the available evidence, longer sleep duration was generally associated with better body composition, emotional regulation, and growth in children aged 0 to 4 years. Shorter sleep duration was also associated with longer screen time use and more injuries. Better-quality studies with stronger research designs that can provide information on dose-response relationships are needed to inform contemporary sleep duration recommendations.

Systematic review of the relationships between sedentary behaviour and health indicators in the early years (0-4 years).

BACKGROUND: The purpose of this systematic review was to examine the relationships between sedentary behaviour (SB) and health indicators in children aged 0 to 4 years, and to determine what doses of SB (i.e., duration, patterns [frequency, interruptions], and type) were associated with health indicators. METHODS: Online databases were searched for peer-reviewed studies that met the a priori inclusion criteria: population (apparently healthy, 1 month to 4.99 years), intervention/exposure and comparator (durations, patterns, and types of SB), and outcome/health indicator (critical: adiposity, motor development, psychosocial health, cognitive development; important: bone and skeletal health, cardiometabolic health, fitness, risks/harm). The quality of the evidence was assessed by study design and outcome using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework. RESULTS: Due to heterogeneity, meta-analyses were not possible; instead, narrative syntheses were conducted, structured around the health indicator and type of SB. A total of 96 studies were included (195,430 participants from 33 countries). Study designs were: randomized controlled trial (n = 1), case-control (n = 3), longitudinal (n = 25), longitudinal with additional cross-sectional analyses (n = 5), and cross-sectional (n = 62). Evidence quality ranged from "very low" to "moderate". Associations between objectively measured total sedentary time and indicators of adiposity and motor development were predominantly null. Associations between screen time and indicators of adiposity, motor or cognitive development, and psychosocial health were primarily unfavourable or null. Associations between reading/storytelling and indicators of cognitive development were favourable or null. Associations between time spent seated (e.g., in car seats or strollers) or in the supine position, and indicators of adiposity and motor development, were primarily unfavourable or null. Data were scarce for other outcomes. CONCLUSIONS: These findings continue to support the importance of minimizing screen time for disease prevention and health promotion in the early years, but also highlight the potential cognitive benefits of interactive non-screen-based sedentary behaviours such as reading and storytelling. Additional high-quality research using valid and reliable measures is needed to more definitively establish the relationships between durations, patterns, and types of SB and health indicators, and to provide insight into the appropriate dose of SB for optimal health in the early years.

Correction to: Systematic review of the relationships between physical activity and health indicators in the early years (0-4 years).

CORRECTION: After publication of the article [1], it has been brought to our attention that an incorrect reference has been used in this article, both in the main body and additional file 2. The reference in question is #105 in the main body and #74 in additional file 2. Here it is cited as "Lindsay H, Brussoni M. Injuries and helmet use related to non-motorized wheeled activities among pediatric patients. Chronic Dis Inj Canada. 2014;34(2-3):74-81".

Systematic review of the relationships between physical activity and health indicators in the early years (0-4 years).

BACKGROUND: Given the rapid development during the early years (0-4 years), an understanding of the health implications of physical activity is needed. The purpose of this systematic review was to examine the relationships between objectively and subjectively measured physical activity and health indicators in the early years. METHODS: Electronic databases were originally searched in April, 2016. Included studies needed to be peer-reviewed, written in English or French, and meet a priori study criteria. The population was apparently healthy children aged 1 month to 59.99 months/4.99 years. The intervention/exposure was objectively and subjectively measured physical activity. The comparator was various volumes, durations, frequencies, patterns, types, and intensities of physical activity. The outcomes were health indicators ranked as critical (adiposity, motor development, psychosocial health, cognitive development, fitness) and important (bone and skeletal health, cardiometabolic health, and risks/harm). The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) framework was used to assess the quality of evidence for each health indicator by each study design. RESULTS: Ninety-six studies representing 71,291 unique participants from 36 countries were included. Physical activity interventions were consistently (>60% of studies) associated with improved motor and cognitive development, and psychosocial and cardiometabolic health. Across observational studies, physical activity was consistently associated with favourable motor development, fitness, and bone and skeletal health. For intensity, light- and moderate-intensity physical activity were not consistently associated with any health indicators, whereas moderate- to vigorous-intensity, vigorous-intensity, and total physical activity were consistently favourably associated with multiple health indicators. Across study designs, consistent favourable associations with health indicators were observed for a variety of types of physical activity, including active play, aerobic, dance, prone position (infants; ≤1 year), and structured/organized. Apart from ≥30 min/day of the prone position for infants, the most favourable frequency and duration of physical activity was unclear. However, more physical activity appeared better for health. Evidence ranged from "very low" to "high" quality. CONCLUSIONS: Specific types of physical activity, total physical activity, and physical activity of at least moderate- to vigorous-intensity were consistently favourably associated with multiple health indicators. The majority of evidence was in preschool-aged children (3-4 years). Findings will inform evidence-based guidelines.

Canadian 24-Hour Movement Guidelines for the Early Years (0-4 years): An Integration of Physical Activity, Sedentary Behaviour, and Sleep.

BACKGROUND: The Canadian Society for Exercise Physiology convened representatives of national organizations, research experts, methodologists, stakeholders, and end-users who followed rigorous and transparent guideline development procedures to create the Canadian 24-Hour Movement Guidelines for the Early Years (0-4 years): An Integration of Physical Activity, Sedentary Behaviour, and Sleep. These novel guidelines for children of the early years embrace the natural and intuitive integration of movement behaviours across the whole day (24-h period). METHODS: The development process was guided by the Appraisal of Guidelines for Research and Evaluation (AGREE) II instrument. Four systematic reviews (physical activity, sedentary behaviour, sleep, combined behaviours) examining the relationships within and among movement behaviours and several health indicators were completed and interpreted by a Guideline Development Panel. The systematic reviews that were conducted to inform the development of the guidelines, and the framework that was applied to develop the recommendations, followed the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) methodology. Complementary compositional analyses were performed using data from the Canadian Health Measures Survey to examine the relationships between movement behaviours and indicators of adiposity. A review of the evidence on the cost effectiveness and resource use associated with the implementation of the proposed guidelines was also undertaken. A stakeholder survey (n = 546), 10 key informant interviews, and 14 focus groups (n = 92 participants) were completed to gather feedback on draft guidelines and their dissemination. RESULTS: The guidelines provide evidence-informed recommendations as to the combinations of light-, moderate- and vigorous-intensity physical activity, sedentary behaviours, and sleep that infants (<1 year), toddlers (1-2 years) and preschoolers (3-4 years) should achieve for a healthy day (24 h). Proactive dissemination, promotion, implementation, and evaluation plans were prepared to optimize uptake and activation of the new guidelines. CONCLUSIONS: These guidelines represent a sensible evolution of public health guidelines whereby optimal health is framed within the balance of movement behaviours across the whole day, while respecting preferences of end-users. Future research should consider the integrated relationships among movement behaviours, and similar integrated guidelines for other age groups should be developed.