The effects of physical activity on female fertility: a narrative review.

Infertility is the inability to conceive after 1 year of regular unprotected sexual intercourse. Modifiable factors such as lifestyle interventions and nonmodifiable factors (advanced maternal age or reproductive disorders) can impact female fertility. Despite the still suboptimal success rates, assisted reproductive technologies (ARTs) remain a useful tool to overcome reproductive challenges. However, additional strategies to improve fertility are still required. Physical activity (PA) impacts overall health, including reproductive function. The effects of PA depend on its frequency, intensity, and duration and may vary depending on the individual's health status and reproductive context. This makes designing a one-size-fits-all PA regimen to improve fertility a particularly challenging task. To address this issue, we review and discuss the existing evidence regarding the impact of PA on the female reproductive system. Human studies indicate that women trying to conceive, women undergoing ART, and pregnant women should engage in regular moderate PA, since it is proven to be beneficial to both women and fetus. In contrast, excessive exercise, especially combined with low caloric intake, can negatively impact ovarian function and the female reproductive axis. Animal studies, in turn, provide relevant insight into the molecular/cellular consequences of PA: on how it affects hormonal changes, follicle development and integrity, oocyte mitochondrial fitness, spindle organization/chromosome alignment, and transcriptomic modifications, otherwise difficult to study in human samples. Overall, understanding how PA alters the female reproductive system might be key to establishing new therapeutic strategies to tackle infertility.