Effect of exercise training on cardiorespiratory fitness, cardiac function, and endothelial function in pregnant people with overweight/obesity: secondary results from a randomised, controlled trial
Authors: Moholdt T , Garnaes K K , Morkved S , Salvesen K A , Ingul C B 
Published: June 2024

Abstract

Introduction
Pregnancy is a cardiovascular stress test, which is superimposed on already adverse trajectories for several health outcomes in individuals with obesity. As such, pregnancy is a critical period for cardiovascular disease (CVD) prevention, especially in people with obesity. Exercise training is a first-line therapy that reduces CVD risk by beneficial effects on cardiorespiratory fitness, cardiac function, and vascular outcomes such as endothelial-dependent dilatation.

Purpose
In a secondary analysis from the Exercise Training in Pregnancy (ETIP) study, we aimed to determine the effectiveness of exercise training during pregnancy on peak oxygen uptake (V̇O2peak), cardiac function, and flow-mediated dilatation of the brachial artery (FMD) throughout pregnancy and postpartum. We hypothesized that exercise training would improve these outcomes, in comparison with a no-exercise control group.

Methods
ETIP is a randomised controlled trial in which participants with a pre-pregnancy body mass index (BMI) ≥ 28 kg/m2 were randomly allocated to an exercise group or a control group in gestational week 12-18. Those in the exercise group were offered three weekly supervised exercise sessions comprising 35 minutes of moderate-intensity treadmill walking followed by 25 minutes of strength exercises. We measured V̇O2peak and FMD at baseline, in gestational week 34-37, and 3 months postpartum, and echocardiography in gestational week 14, 20, and 32, and 6-8 weeks postpartum. Differences between groups were determined using linear mixed models.

Results
Of the 91 participants included in ETIP, 87 participants (age: 31.3 ± 4.2 years, BMI: 34.6 ± 4.3 kg/m2) had data on V̇O2peak, cardiac function, and/or FMD from at least one time-point. There was no significant effect of exercise training on VO2peak in late pregnancy (gestational week 34-37), with an estimated effect of 1.7 mL/min/kg (95% confidence interval [CI], -0.4 to 3.7), compared with the control group (p = .11), or postpartum (1.6 mL/min/kg, 95% CI, -0.2 to 3.4, p = .08). The participants had an average VO2peak of ~27 mL/kg/min 3 months postpartum, which is 14 mL/kg/min (34%) lower than average V̇O2peak of Norwegian females 20-39 years old. There were several significant effects of time (progressing pregnancy) on FMD and cardiac function parameters, but no significant between-group differences in either FMD or any of the echocardiographic outcomes. Only 50% of the participants in the exercise group fulfilled our pre-specified adherence criteria.

Conclusion
Offering pregnant individuals with BMI ≥ 28 kg/m2 a supervised exercise training intervention did not improve cardiorespiratory fitness, cardiac function parameters, or endothelial-dependent dilatation of the brachial artery. The main reason for no effect of the intervention on these outcomes was probably the low adherence to the exercise training.