To HIIT or not to HIIT? The question pregnant women may be searching for online: a descriptive observational study

Is fetal well-being jeopardised during high-intensity interval training?

ABSTRACT

Objectives

To explore the acute effects of high-intensity interval training on fetal heart rate (FHR) and uteroplacental blood flow.

Method

Elite (n=10) and recreational athletes (n=50) participated in an experimental laboratory study involving 5×5 min intervals of high-intensity exercise on both a treadmill and cycle ergometer, with a 4 min pause between intervals for measurement of FHR and uteroplacental blood flow. Target intensity was 17 on Borg's rating of perceived exertion (RPE) scale and 90% of estimated maximal maternal heart rate (MHRmax).

Results

Mean exercise intensity was 16.4 (SD 1.0) RPE and 89.4 (SD 3.8) % of MHRmax during running and 16.0 (SD 1.0) RPE and 84.6 (SD 5.0) % of MHRmax during cycling. Mean FHR was 140.9 (SD 27.4) beats per minute (bpm) during pauses between running bouts and 148.9 (SD 16.0) bpm during pauses between cycling bouts. Six cases of prolonged fetal bradycardia (<100 bpm for >3 min) occurred during running, leading to the termination of exercise. The mothers exercised at 17-18 on Borg's RPE scale and 86.4%-92.6% of MHRmax in these cases. All cases were normalised within 8 min of ending the protocol. There were no cases of prolonged fetal bradycardia during cycling. Exercise was terminated for three women during running and two women during cycling due to fetal tachycardia (≥180 bpm for >4 min during rest).

Conclusion

Despite cases of fetal bradycardia and tachycardia, our results indicate that highly active women can engage in multiple intervals of high-intensity interval training without apparent harm to fetal well-being.

Navigating Pregnancy: Information Sources and Lifestyle Behavior Choices-A Narrative Review

Background: Accessible health information during pregnancy is important to positively affect maternal and fetal health. However, the quality and accuracy of health information can greatly vary across numerous sources. This narrative review is aimed at summarizing the literature on pregnant individuals' information sources and how these sources influence their habits toward GWG, PA, and nutrition. Such data will highlight preferences and needs, reveal challenges, and identify opportunities for improvement. Methods: We searched PubMed for studies published in the last decade. Out of 299 studies initially identified, 20 (16 quantitative and four qualitative) met the eligibility criteria (investigating information sources and their influence on health habits toward GWG, PA, nutrition, pregnant participants, adequate data reporting, and being available in full text). Results: Primary sources of health information varied. The Internet (26%-97%) and healthcare providers (HCPs) (14%-74%) predominated, followed by family/friends (12%71%), books/magazines (49%-65%), and guidelines/brochures (25%-53%). Despite the widespread use of the Internet, HCPs were considered the most reliable source. The use of the Internet to retrieve health information was reported to be 2-4 h a week, and < 50% discussed the online information with their HCP. The Internet was also used as a supplementary resource on topics raised by HCPs. Regarding the influence on health habits, the Internet, HCPs, media, and family positively influenced GWG and promoted adherence to recommended guidelines (OR = 0.55-15.5). Only one study showed a positive association between Internet use and PA level. The Internet, media, HCPs, and information brochures were associated with better adherence to nutritional recommendations. Conclusions: Pregnant individuals relied on the Internet and HCP, with a preference for the Internet despite trust in midwives. Several sources of health information were positively associated with adherence to GWG and nutrition recommendations. Improving the quality of online information should be a priority for policymakers and health authorities.

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.

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.

ACTIVE PREGNANCY: Workshop on Promotion of Physical Activity in Pregnancy for Exercise Professionals

Introduction

A one-day workshop on promotion of physical activity in pregnancy for exercise professionals was delivered during 2021, to 137 participants. The main aim of this workshop was to motivate and prepare exercise professionals for promoting physical activity and implementing prenatal exercise programs, in their respective private or public fitness centers or other physical activity settings.

Methods

The contents of the workshop were focused on six topics based on the "Pregnancy and Postpartum Exercise Specialist" educational standards by EuropeActive and the "Exercise and Physical Activity during Pregnancy and Postpartum" textbook published by Springer. Participants provided feedback on the effectiveness and satisfaction with the workshop.

Results

Overall evaluations from the feedback forms showed that majority of the participants agreed that the workshop achieved its objectives with a major recommendation as to the organization of more short duration workshops, the inclusion of practical sessions, and the separation of the contents addressing the postpartum period.

Discussion

The workshop on promotion of physical activity in pregnancy for exercise professionals was successfully organized and the participants are looking forward for future ones.

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.