Physical activity influences numerous systems in the body that are directly linked to reproductive health for both men and women. The relationship is not simply linear, meaning more exercise is not always better. Instead, the effect of physical activity on conception relies heavily on the specific type, frequency, and intensity of the movement.
How Moderate Exercise Supports Fertility
Regular, moderate physical activity optimizes body mass index (BMI) and the regulation of metabolic health. Maintaining a healthy weight helps to normalize the production of reproductive hormones, as excess fat tissue can disrupt this delicate balance through the overproduction of estrogen.
For women, particularly those with Polycystic Ovary Syndrome (PCOS), exercise is especially beneficial because it improves insulin sensitivity. When cells become more responsive to insulin, it helps reduce the high levels of androgens that can interfere with the ovary’s ability to release an egg. This metabolic improvement can lead to more consistent menstrual cycles and a better chance of successful ovulation. Men also benefit, as moderate activity helps regulate hormones like testosterone and can improve sperm quality, including their concentration and motility.
Physical activity is a powerful tool for managing stress. Exercise helps to lower the levels of the stress hormone cortisol, which, when chronically elevated, can negatively impact the hormonal axis governing reproduction. Furthermore, consistent movement increases blood circulation throughout the body, delivering better oxygen and nutrient supply to the reproductive organs, which is beneficial for both uterine lining health and testicular function.
The Critical Distinction: Overtraining and Fertility Decline
While moderate exercise is helpful, excessive or overly intense training can actively suppress the reproductive system. This is especially true for chronic endurance training, such as high-volume running or cycling, which can signal to the body that it is under too much physical stress. The resulting hormonal suppression can disrupt the Hypothalamic-Pituitary-Ovarian (HPO) axis.
In women, this disruption can lead to functional hypothalamic amenorrhea, which is the absence of menstruation and ovulation. This state is frequently linked to Relative Energy Deficiency in Sport (RED-S), where the energy consumed is not enough to cover the energy expended during intense activity.
The high physical strain keeps cortisol levels elevated, interfering with the delicate balance of reproductive hormones like estrogen and progesterone. Studies show that women engaging in five or more hours of vigorous exercise per week may face a significantly reduced chance of conception compared to those who are less active.
For men, overtraining can also have a detrimental impact. Extreme endurance exercise has been linked to a suppression of the hypothalamic-pituitary-gonadal axis, resulting in decreased testosterone levels and a reduction in sperm concentration. The physical stress and accompanying rise in cortisol can contribute to oxidative stress in the testes, which negatively affects the quality and motility of sperm.
Exercise Recommendations for Optimal Conception
Moderate-intensity exercise is recommended, which can be defined using the “talk test” as a level where you can speak in full sentences but cannot sing. Aiming for around 150 minutes of this level of activity per week is a common guideline for adults.
The ideal routine should incorporate a mix of activity types, including low-impact cardiovascular work and resistance training. Activities such as brisk walking, swimming, light cycling, and yoga are excellent choices. Strength training, when kept to a moderate intensity, is also beneficial for improving metabolic health and supporting hormonal regulation.
It is helpful to adjust the intensity of workouts based on the phases of the menstrual cycle. The follicular phase, from the start of the period to ovulation, can typically accommodate more intense workouts due to rising energy levels. After ovulation, during the luteal phase and the two-week wait, it is advisable to transition to gentler, more restorative movements. Prioritizing rest and recovery is paramount, and it is important to listen to the body and avoid pushing through pain or extreme exhaustion.