Acute Effects of High Intensity Training in Pregnancy on Fetal Well-being and Blood Flow Distribution

Not Applicable

Completed

• Conditions: Pregnancy
• Interventions: Behavioral: Single high-intensity interval training session

• Registration Number: NCT04288479
• Lead Sponsor: Norwegian University of Science and Technology

Brief Summary

Pregnant women are recommended to be physically active ≥150 min/week, but \<15% of Norwegian women attain this goal. Several well-designed studies on lifestyle interventions focusing primarily on exercise training in overweight/obese pregnant women have reported disappointing outcomes with regard to maternal glycemic control, gestational weight gain and infant outcomes. Low adherence to the training program was found to be a problem; the participants did not enjoy the exercise program and had difficulties scheduling time to exercise. Pregnant women also report that they are not sure what exercises are safe during pregnancy.

High intensity interval training (HIT), defined as short periods of intense activity separated by low-intensity breaks, has proved to induce superior improvements in insulin sensitivity and fitness compared with continuous moderate intensity training in individuals at increased risk for cardiometabolic diseases. Even short-term (6 weeks) HIT with brief (15-60 sec) work-bouts and a total time commitment of \<45 min per week, improves insulin sensitivity similar to that attained after 6 months of traditional endurance training.

HIT is feasible and enjoyable for individuals with low fitness level and with obesity.

HIT is therefore a highly potent intervention that elicits important changes in a range of clinically relevant health outcomes in reproductive-aged women.

This study will investigate fetal responses to a single bout of HIT. Preliminary data of the investigators suggest that HIT does not negatively influence fetal heart rate. Others have reported that uterine and umbilical blood flow are not changed during or following acute exercise. However, no previous study has determined the acute effect of HIT on uterine blood flow and there are no studies investigating the fetal blood flow distribution in response to exercise. Since the relative distribution of blood to the fetal liver is associated with newborn adiposity, fetal blood flow distribution in response to exercise can provide insight about the effect of maternal exercise on offspring health.

Detailed Description

Not available

Study Timeline

• Study First Submitted: 2020-02-26
• Study First Submitted QC: 2020-02-26
• Study First Posted: 2020-02-28
• Study Start: 2022-02-23
• Primary Completion: 2025-04-23
• Study Completion: 2025-04-23
• Status Verified: 2025-05
• Last Update Submitted: 2025-05-20
• Last Update Posted: 2025-05-21

Recruitment & Eligibility

• Status: COMPLETED
• Sex: Female
• Target Recruitment: 34

Inclusion Criteria

• pregnant, gestational week 22-36
• singleton fetus
• no known diseases
• capable of cycling on an ergometer bike

Exclusion Criteria

• hypertension
• gestational diabetes mellitus
• any contraindication to exercise training

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: SINGLE_GROUP

Arm && Interventions

Group	Intervention	Description
Doing a single HIT session in gestational week 22-36	Single high-intensity interval training session	-

Primary Outcome Measures

Name	Time	Method
blood flow in fetal veins	1 day	examined by Doppler ultrasound during 30 minutes
blood flow in fetal arteries	1 day	examined by Doppler ultrasound during 30 minutes

Secondary Outcome Measures

Name	Time	Method
maternal heart rate	1 dag
Maternal diastolic blood pressure	1 day
Maternal body weight	1 day
Maternal height	1 day
Fetal heart rate	1 day
Umbilical vein diameter	1 day
Maternal systolic blood pressure	1 day

Trial Locations

Locations (1)

Dept Circulation and Medical Imaging, EXCAR Exercise Lab; 🇳🇴 Trondheim, Norway