Effects of 8-Week Online, Supervised High-Intensity Interval Training on the Parameters Related to the Anaerobic Threshold, Body Weight, and Body Composition during Pregnancy: A Randomized Controlled Trial
Question
Does online supervised HIIT improve or maintain anaerobic-threshold-related exercise capacity and body composition in pregnant women compared with online education?
Summary
In women with uncomplicated singleton pregnancies, an 8-week online supervised bodyweight HIIT program helped maintain anaerobic-threshold-related exercise capacity and improved fat-mass and fat-free-mass percentages compared with an online education program. No adverse obstetric or neonatal effects were observed, but the study analyzed only 49 women and excluded lower-attendance HIIT participants.
Methodology
- Caucasian women with uncomplicated singleton pregnancies.
- 49 participants.
- Bodyweight exercises targeting major muscle groups, including lunges, squats, jumps, and upper-body combinations.
- Work intervals: 30-60 seconds.
- Recovery: Equal-length rest break; ratios varied 1:2, 1:1, or 2:1 depending on ability, pregnancy stage, and progression.
- Intensity: Participants were instructed to exceed their individually measured HR at anaerobic threshold for as long as comfortable; HR/AT averaged 87 ± 5% HRmax.
- 60 minutes.
- 3 sessions per week.
- 8 weeks.
- Randomized controlled trial.
- Anaerobic-threshold parameters, Body composition, and Pregnancy and neonatal outcomes were tracked.
Outcomes
Anaerobic threshold
HIIT maintained or improved anaerobic-threshold-related measures while education participants deteriorated.
Post VO2/AT HIIT 20.15 ± 3.47 vs EDU 15.67 ± 2.89 mL/kg/min, p < 0.01; post HR/AT HIIT 151 ± 10 vs EDU 143 ± 12 bpm, p < 0.01.
Exercise duration above thresholds
HIIT improved time between aerobic and anaerobic thresholds and time above anaerobic threshold.
Time between HR/AerT and HR/AT 76 to 92 s, p < 0.01; time above HR/AT 117 to 160 s, p < 0.01.
Body composition
Fat mass percentage decreased and fat-free mass percentage increased after HIIT, while body weight and BMI rose in both groups as expected during pregnancy.
%FM 30 to 28%, p < 0.01; %FFM 70 to 72%, p < 0.01; post %FM lower than EDU, p < 0.05.
Safety
No adverse effects on pregnancy, childbirth, or neonatal outcomes were observed in either group.
Premature birth in one EDU participant was reported as unrelated to physical activity or lifestyle.
Insights
- Online real-time supervision can support prenatal HIIT adherence and safety in uncomplicated pregnancies.
- Pregnancy HIIT should be individualized to diagnostic exercise testing, Talk Test/RPE, symptoms, and obstetric clearance.
- Findings should not be generalized to complicated pregnancies, multiple pregnancies, or unsupervised high-intensity workouts.
Limitations
- Analyzed sample was 49 participants after exclusions.
- Caucasian women only.
- No dietary intake data.
- No comparison with online moderate-intensity continuous exercise.
- Per-protocol style exclusion of HIIT participants attending less than 70% of sessions may bias effects.
- Cycle ergometer HR thresholds may be lower than treadmill-derived values.
Safety
- No adverse effects on pregnancy, childbirth, or neonatal outcomes were observed.
- One premature birth occurred in the education group and was judged unrelated to physical activity or lifestyle factors.
- No HIIT absences were due to exercise-related health issues or sessions being considered too intense.
- Participants were women with uncomplicated pregnancies and continued routine obstetric care.