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

Acute Effects of HIT on Fetal Well-being and Blood Flow Distribution - a Pilot Study

Status
Completed
Phases
NA
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT04288479
Acronym
HITFLOW
Enrollment
34
Registered
2020-02-28
Start date
2022-02-23
Completion date
2025-04-23
Last updated
2025-05-21

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Pregnancy

Keywords

Exercise, High Intensity Interval Training, Pregnancy Outcome, Placental Circulation, Fetal Blood, Heart Rate, Fetal

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.

Interventions

BEHAVIORALSingle high-intensity interval training session

10 minutes warming up at low-to-moderate intensity, 8x30 seconds high intensity interval training with fetal heart rate measurement after each 30 second work-bout, 2 minutes recovery at low-to-moderate intensity. Continuous monitoring of maternal heart rate.

Sponsors

St. Olavs Hospital
CollaboratorOTHER
Norwegian University of Science and Technology
Lead SponsorOTHER

Study design

Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
TREATMENT
Masking
NONE

Intervention model description

before-after intervention effect measurement

Eligibility

Sex/Gender
FEMALE
Age
18 Years to No maximum
Healthy volunteers
No

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

Design outcomes

Primary

MeasureTime frameDescription
blood flow in fetal veins1 dayexamined by Doppler ultrasound during 30 minutes
blood flow in fetal arteries1 dayexamined by Doppler ultrasound during 30 minutes

Secondary

MeasureTime frame
Maternal diastolic blood pressure1 day
maternal heart rate1 dag
Umbilical vein diameter1 day
Maternal body weight1 day
Maternal height1 day
Fetal heart rate1 day
Maternal systolic blood pressure1 day

Countries

Norway

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 4, 2026