February 27, 2026, 11:45 am | Read time: 5 minutes
Exercising for physical fitness is associated with countless positive adaptations—be it in relation to the cardiovascular system, the muscles, or even the psyche. However, it is less well known that sport can also have an impact on fertility. FITBOOK fitness expert Alina Bock explains the effects of sport on female fertility.
A healthy amount of exercise can support the natural hormonal balance and a healthy weight. This promotes fertility in women, whereas too much sport can significantly reduce fertility. But what is the right amount of exercise to support hormonal balance and subsequently increase fertility?
Overview
Common Causes of Reduced Fertility in Women
An unfulfilled desire to have children can have many causes, such as:
- Overweight
- Underweight
- PCOS
- Thyroid problems
- Endometriosis
- Stress
- Infections
Exercise can have an impact on some of these causes, including PCOS, obesity, underweight and stress.
PCOS as a Common Cause of Infertility
Polycystic ovary syndrome, or PCOS for short, is one of the most common causes of infertility, accounting for five to ten percent, is one of the most common causes of an unfulfilled desire to have children. It is a hormonal disorder that is often associated with an excess of male hormones. The consequences are a disrupted menstrual cycle, increased body hair, hair loss, and infertility. Obesity is a common side effect of PCO syndrome.
Study Shows That Exercise Can Have Positive Effects on the Progression of PCOS
PCO syndrome is often treated with medication. However, studies show that exercise can have positive effects on the hormonal balance in PCOS.
A study from 2015 investigated the effects of a structured training program on anthropometric, cardiovascular, and metabolic parameters in women with PCOS. For this purpose, 30 affected women were divided into two groups. One group carried out an eight-week training program, while the other served as a control group and did not undergo an exercise program. After the eight-week exercise program, the exercise group showed significantly lower values for diastolic blood pressure, respiratory rate, total cholesterol, fasting blood glucose, and insulin resistance. In addition, the exercise group showed a significantly higher oxygen uptake and shorter menstrual cycles. Exercise can therefore be a good method for treating PCO syndrome in order to improve hormone balance and shorten the menstrual cycle.1
Obesity as a Cause of Infertility
Another factor that can have a negative impact on hormone balance is being overweight. Too much fatty tissue leads to increased oestrogen production, which in turn can lead to a disrupted menstrual cycle and irregular ovulation. Being overweight also promotes insulin resistance and increases insulin levels. The consequence of high insulin levels is the increased production of male hormones, which unbalances the female hormone balance and thus limits fertility.
Exercise and Diet Can Promote Healthy Weight Loss
Exercise in the form of cardio and muscle training can be recommended to regulate a disturbed hormone balance as a result of being overweight. Strength training promotes the development and maintenance of muscles as well as insulin sensitivity and supports fat loss by burning calories. In addition to this, cardio training is recommended, which also boosts fat burning and metabolism and has a positive effect on the cardiovascular system.
Women should also focus on a balanced diet with a calorie deficit in order to accelerate weight loss and positively change the hormonal balance as a result. It is important to note that a slight calorie deficit (300 to 500k kilocalories) is definitely sufficient. Too large a calorie deficit and too rapid weight loss can have a negative effect on hormone levels.
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The Consequences of Too Much Exercise for the Female Body
However, it is not only too little physical activity and being overweight that can upset the hormone balance. Too much sport can also disrupt the hormonal balance and menstrual cycle in women and thus have a negative impact on fertility. Particularly in combination with a low body fat percentage, the hormone balance is disturbed by a reduced production of oestrogen.
The normal body fat percentage for women aged 20 to 39 is between 21 and 32.9 percent. An excessive amount of sport and a low calorie intake, as is the case in bodybuilding or competitive sport, for example, can lead to a low body fat percentage. This favors the decrease of the female sex hormone oestrogen and often leads to the ovaries no longer releasing eggs and consequently to a missed period.
Amenorrhea can be reversed in the vast majority of cases by increasing the body fat percentage and reducing the exercise program. Women who notice that they are not menstruating and at the same time have a high level of exercise and a very low body fat percentage should reduce their exercise and increase their calorie intake in order to normalize their hormone balance.
How Much Exercise is Advisable for Women to Increase Fertility?
Exercise does not necessarily always have a positive effect on fertility—too much exercise can also have the exact opposite effect. But before you get too worried, you should also be aware that training rarely has a negative impact on hormone levels. This is most common in competitive sports and bodybuilding competitions, where the body fat percentage is reduced to a minimum. In order for sport to have a negative effect on the female hormone balance, a daily sports program in combination with a very low-calorie intake is necessary.
In most cases, exercise in combination with a healthy and balanced diet is beneficial for fertility by reducing excess weight, increasing insulin sensitivity, positively influencing the course of PCO syndrome, and thus promoting hormonal balance.