Emelie Mass Dalhaug is a PhD candidate at the Department of Sports Medicine, Norwegian School of Sport Sciences (NIH). On May 8, 2026, she defends her doctoral thesis, What happens when pregnant athletes push beyond conventional exercise guidelines? An experimental and prospective study on maternal and fetal health outcomes, at NIH, Auditorium Innsikt, 10:15–16:00.
The aim of the Strong Mama project was to investigate the effects of high‑intensity exercise and heavy‑load resistance training on maternal and fetal health in pregnant elite and recreational athletes, an area where current recommendations have traditionally been conservative and have discouraged such training.
In the laboratory, participants completed high‑intensity intervals on a treadmill and cycle ergometer, as well as a heavy‑load resistance protocol, while researchers measured fetal heart rate and blood flow to the placenta and fetus using ultrasound between each interval or exercise. In addition, the project included a prospective component in which participants’ training habits, pregnancy course, health, birth outcomes, and neonatal health were recorded through a questionnaire and a follow‑up interview.
The findings from this project suggest that high‑intensity exercise, heavy‑load resistance training, and a high training volume were generally well tolerated by both the pregnant athletes and their fetuses. Together with previous research, these results challenge current conservative recommendations and indicate that higher intensities and loads may be safe for well‑trained pregnant women. In practice, this means that well-trained pregnant women may be able to continue interval training and heavy-load resistance training during pregnancy, provided that training is individually adapted, includes sufficient recovery, and is supported by regular prenatal follow-ups.
Although more research on the long-term effects is needed, the growing evidence base may eventually support guidelines that better reflect the fitness, training experience, and exercise routines of elite and recreational athletes.
Overall, the findings suggest that well-trained pregnant women may have greater flexibility in their training than current recommendations reflect.
Results
- High‑intensity interval training was generally well tolerated by both the mother and the fetus, and fetal heart rate remained mostly within the normal range (110–160 bpm).
- Transient bradycardia (<110 bpm) occurred in a small number of fetuses, particularly during running. Six episodes lasted >3 minutes, but all returned to normal spontaneously within a few minutes after exercise cessation.
- A few episodes of fetal tachycardia (≥180 bpm) were recorded during running and cycling, but also these resolved quickly.
- Heavy‑load resistance training resulted in stable fetal responses, with small and expected variations in fetal heart rate.
- Supine exercise was generally well tolerated by both mother and fetus.
- In the prospective component, participants experienced favorable pregnancy and birth outcomes, including a low rate of preterm birth (1.6%) and no cases of low birthweight.
- A high training volume during pregnancy did not appear to increase the risk of complications among healthy, well‑trained pregnant women.
Read the thesis here.
Committee
Chair
- Thor Einar Andersen, IIM, NIH
Opponents
- Professor Rita Santos Rocha, ESDRM Sport Sciences School of Rio Maior, Polytechnic Institute of Santarém, Portugal
- Associate Professor Laila Ottesen, Institutt for idrett og ernæring, Københavns universitet, Danmark
Supervisors
- Main supervisor: Lene Hagen Haakstad, IIM, NIH
- Co-supervisors: Kari Bø, IIM, NIH, and Wendy Brown, University of Queensland, Australia
Program
