Exercise prior to assisted fertilization in overweight and obese women (FertilEX): study protocol for a randomized controlled trial

Overweight and obese women show reduced conception rates compared to women of normal weight. Insulin resistance and increased amount of visceral fat may be important mechanisms for reduced fertility in these women. Exercise training, in particular with high intensity, has previously been found to improve insulin sensitivity in overweight subjects. This study will assess if regular high-intensity interval training will improve the pregnancy rate after assisted fertilization compared to usual care only in overweight and obese women. We hypothesize that the intervention will improve pregnancy rate and insulin sensitivity compared to the control group. The FertilEX study is a randomized, controlled trial in which 140 women with body mass index (BMI) >25 kg/m(2) accepted for assisted fertilization will be randomized (1:1) to an intervention group or a control group. The intervention group will do high-intensity interval training three times per week for 10 weeks before assisted fertilization. The control group will receive standard care assisted fertilization only. The primary outcome measure is ongoing pregnancy 7-8 weeks after embryo transfer. Secondary outcome measures are insulin sensitivity, peak oxygen uptake, brachial flow-mediated endothelial function, levels of reproductive hormones, and body composition. The results of this trial will provide knowledge about the effects of high-intensity exercise before assisted fertilization in subfertile overweight/obese women. If the intervention leads to beneficial effects on outcome measures, such programs should be considered as part of regular fertility care procedures for this population of women. ClinicalTrials.gov: NCT01933633 . Registered on 28 August 2013.