# Changes in pain perception during pregnancy after one-time maximal physical exertion and an 8-week high-intensity interval training

PMID: 38148904
Journal: Frontiers in Physiology
Published: 2023-12-12
Authors: Leźnicka K, Gasiorowska A, Pawlak M, Jażdżewska A, Maciejewska-Skrendo A, Chudecka M, Szumilewicz A

## Question

Do a one-time maximal progressive cardiopulmonary exercise test and an 8-week high-intensity interval training program alter objective and subjective pain perception in pregnant women?

## Summary

This single-arm study followed pregnant women with uncomplicated singleton pregnancies through an 8-week online HIIT program. The study measured pressure pain threshold, pressure pain tolerance, and subjective pain before and after a maximal cycling test and before and after the training program. Pain tolerance increased after the acute maximal exercise test and after the 8-week HIIT intervention, while pain threshold did not improve. The authors reported no observed adverse effects on pregnancy development, delivery, or neonatal conditions.

## Population

- Thirty-five women with singleton, uncomplicated pregnancies between 13 and 28 weeks of gestation entered an 8-week online HIIT program.
- Sample size: 35
- Age: 24-42 years; mean 31.26 +/- 4.22 years
- Sex: Pregnant women
- Fitness level: Mixed IPAQ categories: 17.14% low, 45.71% medium, 37.14% high.
- Health status: Uncomplicated singleton pregnancy with obstetric care provider consent.

## Methodology

- Single-arm pre-post intervention study with repeated pain measurements before and after acute maximal CPET and before and after an 8-week online HIIT program.
- 8 weeks
- Baseline and postintervention laboratory testing plus online HIIT classes via MS Teams.

## Protocol

- 8-week prenatal HIIT.
- Modality: Online bodyweight exercise.
- Work intervals: 30-45 seconds during high-intensity interval portion.
- Recovery: 15-60 seconds depending on week, ability, pregnancy stage, and progress.
- Sets or repetitions: Four sets and four cycles/exercises per session.
- Intensity: Expected to exceed individually determined anaerobic threshold; monitored with heart rate, Borg 0-10 RPE, and Talk Test.
- Session duration: Approximately 47-60 minutes including warm-up, 15-20 minute interval block, accessory exercises, and cool-down.
- Frequency: Three online classes per week.
- Program length: 8 weeks.
- Progression: Work/rest progressed from 30/60 seconds in weeks 1-2 to 30/15 seconds in week 8, with intermediate 45/45 and 30/30 prescriptions and changing between-set rests.

## Outcomes

### Pressure pain threshold
Status: no clear change
HIIT did not significantly affect pain pressure threshold; CPET effect was only marginal and in the direction of lower threshold after exercise.

PPT HIIT beta = -.11, SE = .08, t = -1.41, p = .159; CPET beta = -.15, SE = .08, t = -1.88, p = .061.

### Pressure pain tolerance
Status: improved
Pain tolerance increased significantly after both CPET and the 8-week HIIT intervention, with the authors describing the HIIT effect as stronger.

PTOL HIIT beta = .43, SE = .06, t = 7.09, p = .001; CPET beta = .16, SE = .06, t = 2.55, p = .011; marginal R2 = 10.57%.

### Subjective pain
Status: worse/safety concern
Subjective pain experience was higher after HIIT; CPET did not significantly affect subjective pain overall.

VAS HIIT beta = .31, SE = .06, t = 5.22, p = .001; CPET beta = -.03, SE = .06, t = -0.52, p = .600; marginal R2 = 5.22%.

### Safety
Status: unclear
The authors stated they observed no adverse effects on pregnancy development, delivery, or neonatal conditions.

## Practical Insights

- Prenatal HIIT in this study was not just intervals; it included screening, online specialist supervision, warm-up, breathing/posture instruction, pelvic floor work, and relaxation.
- For uncomplicated pregnancies with obstetric clearance, bodyweight HIIT can be structured with short intervals and flexible work/rest ratios.
- The evidence is safety-sensitive and should be framed as preliminary because the study lacked a no-exercise or moderate-intensity comparison group.

## Limitations

- Single-arm design with no inactive or moderate-intensity comparison group.
- Small sample.
- Only uncomplicated singleton pregnancies were included.
- One participant did not complete the program.
- Attendance and actual achieved training intensity were not reported.
- Pain was assessed at limited timepoints, with no postpartum follow-up.

## Safety And Adherence

- No adverse effects of the HIIT intervention on pregnancy development, delivery, or neonatal conditions were observed by the authors.
- The study excluded multiple pregnancies and contraindications to increased exertion.
- Obstetric care provider consent was required.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/38148904/) (pubmed)
- [DOI](https://doi.org/10.3389/fphys.2023.1304534) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10750353/) (full text)

## Agent Guidance

Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.