# 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 PMID: 36558438 Journal: Nutrients Published: 2022-12-11 Authors: Yu H, Santos-Rocha R, Radzimiński Ł, Jastrzębski Z, Bonisławska I, Szwarc A, Szumilewicz A ## 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. ## Population - Caucasian women with uncomplicated singleton pregnancies. - Sample size: 49 - Age: 31 ± 4 years at recruitment. - Sex: Pregnant women only. - Fitness level: Mixed baseline physical activity; program offered regardless of fitness level or motor skill. - Health status: Uncomplicated singleton pregnancy, gestational age not higher than 28 weeks at eligibility. ## Methodology - Randomized controlled trial. - 8 weeks - Online supervised sessions from Gdansk University of Physical Education and Sport, Poland, during 2021. - Randomized and controlled study design. ## Protocol - Online supervised prenatal HIIT. - Modality: 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. - Sets or repetitions: 15-20 minute high-intensity interval portion within each session; exact interval count individualized. - Intensity: Participants were instructed to exceed their individually measured HR at anaerobic threshold for as long as comfortable; HR/AT averaged 87 ± 5% HRmax. - Session duration: 60 minutes. - Frequency: 3 sessions per week. - Program length: 8 weeks. - Progression: Work/rest ratios and exercises were tailored to participant ability, pregnancy stage, and training progression. - Online education. - Modality: Weekly synchronous healthy-lifestyle and physical-activity education. - Intensity: Participants were encouraged to meet at least 150 minutes/week of moderate-to-vigorous activity on their own using Talk Test and RPE. - Session duration: Weekly education class. - Frequency: 1 class per week plus self-directed activity as desired. - Program length: 8 weeks. - Progression: No structured exercise progression. ## Outcomes ### Anaerobic threshold Status: improved 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 Status: improved 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 Status: improved 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 Status: no clear change 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. ## Practical 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 And Adherence - 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. ## Original Sources - [PubMed](https://pubmed.ncbi.nlm.nih.gov/36558438/) (pubmed) - [DOI](https://doi.org/10.3390/nu14245279) (doi) - [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9781372/) (full text) ## Agent Guidance Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.