‘Hormones and Sport’

Article published in: 6 | MEDNews 2025

Natural hormonal changes can influence athletic performance in different stages of life for both women and men. In addition, athletic activities also influence hormonal changes in humans.

The following is an attempt to summarise this complex topic.

Naturally, different endocrine systems are affected in different ways.

The focus is on the following systems:

1. Sex hormones (female cycle, oestrogens – ovaries; testosterone – testicles)
2. Obesity
3. Stress hormones (adrenaline, cortisol, etc.)
4. Thyroid function (Hashimoto’s disease, etc.)
5. Hormone abuse
6. Vitamin D hormone

Influence of the female cycle and changes in sex hormones on athletic performance

Female cycle and sport

Many women now tailor the intensity and type of their sporting activities to their cycle, with the female cycle phases having the following effects on athletic performance:

• Menstruation (days 1–5): Many women report feeling tired, crampy or unwell, which can affect their performance. However, some women also feel energetic and productive.
• Follicular phase (days 6–14): During this phase, oestrogen levels rise, often leading to increased energy and better performance in endurance sports. Recovery may also be faster.
• Ovulation phase (day 14): During ovulation, testosterone levels may rise, which can lead to increased performance. Many women report increased performance during this time.
• Luteal phase (days 15-28): Progesterone levels rise, which can lead to increased fatigue and emotional changes. Some women experience reduced performance during this phase, while others continue to perform well.

It is important to note that the effects of the cycle vary from woman to woman. Individual differences, training experience and adjustments to the training plan can also play a role.

The pill and sport

When women take hormonal oral contraceptives, the influence of cycle-related hormone fluctuations is not quite as pronounced. In particular, when the pill is taken continuously and there is no menstrual bleeding, premenstrual problems (PMS) are reduced or non-existent.

Influence of physical activity and weight on the female cycle and sex hormones (also men)

If the time, duration and intensity of physical activity are increased beyond a certain level, this can lead to a lack of menstruation (amenorrhoea). This is particularly likely to occur if body weight is also reduced at the same time. This is a common observation in female athletes, where low body weight is desirable for achieving peak performance. Long-distance runners are a typical example.

However, male marathon runners also experience a reduction in testosterone depending on weight loss. Frequent complications of this training situation are the occurrence of fatigue or stress fractures. Treatment options in such situations include:

• Weight normalisation (BMI >18 kg/m2)
• Cycle normalisation or taking oral contraceptives
• Avoiding a catabolic (negative balance) metabolic situation through increased protein intake

Menopause and sport

Menopause can have various effects on a woman’s athletic performance:

• Hormonal fluctuations: During menopause, oestrogen and progesterone levels drop, which can lead to changes in metabolism and muscle mass. This can have a negative effect on strength and endurance.
• Bone health: The decline in oestrogen can increase the risk of bone loss (osteoporosis), which can impair the ability to participate in certain sports, especially those involving high impact, and increase the risk of fatigue or stress fractures.
• Energy levels: Many women report fatigue and reduced energy levels during menopause, which can have a negative impact on motivation and performance during exercise.
• Temperature regulation: Hot flushes and sleep disturbances, which are common during menopause, can impair performance and the ability to recover.
• Changes in body fat: Changes in fat distribution, often leading to more body fat in the abdominal area, can affect overall well-being and performance.

Despite these challenges, many women remain physically active during menopause and can maintain or even improve their performance by adjusting their training and eating a balanced diet. Regular exercise can also help alleviate some of the symptoms of menopause. Substitution with oestrogen and progestogens (hormone replacement therapy) in women with a uterus, or oestrogen alone in women without a uterus, alleviates menopausal symptoms and leads to a normalisation of performance.

Contraindications must be observed.

Obesity and exercise

People who are overweight are always advised to exercise more in order to lose weight. However, this becomes increasingly difficult as weight increases. A vicious cycle develops exponentially, which becomes more and more challenging to break as BMI increases. It is much more complex to get a body with a BMI of 40 kg/m2 moving than one with a BMI of 18 kg/m2. Not only does the high level of exertion increase musculoskeletal complaints, but declining fitness combined with increased demand also makes meaningful physical activity that leads to weight loss impossible in some cases. The regulation of fat and muscle tissue is heavily dependent on the body’s own testosterone (in both women and men). It is important to note that this regulation also plays a role in testosterone in women, which is naturally produced in the adrenal glands. In men, testosterone naturally comes from the testicles and only a small amount from the adrenal glands. Men who supply testosterone to the body externally (injections or gels) suppress the body’s own production. The following correlations are noteworthy:

• Fat tissue and hormones: Adipose tissue produces oestrogen, a hormone that can inhibit testosterone production. A higher percentage of body fat can lead to an imbalance between testosterone and oestrogen. Less testosterone leads to less muscle mass in women and men.
• Inflammation: Overweight people often have chronic inflammation, which can negatively affect hormone production. Inflammation markers can impair the function of the testicles, where testosterone is produced. Consuming refined sugar leads to non-specific inflammation in the body and thus indirectly to testosterone deficiency.
• Insulin resistance: Obesity is often associated with insulin resistance, which can disrupt hormone balance. High insulin levels can inhibit testosterone production. High insulin levels are induced by the consumption of sugar and other carbohydrates.
• Reduced physical activity: Being overweight can limit physical activity, which can also lead to lower testosterone levels, as physical exercise can stimulate testosterone production.
• Sleep apnoea: Overweight men and women have a higher risk of sleep apnoea, which can interfere with sleep and lead to a decrease in testosterone levels.

These factors combine to mean that men and women with obesity often have lower testosterone levels.

Stress, exercise and hormones

Eustress and distress are two types of stress that have different effects on well-being. Eustress refers to positive stress that is perceived as motivating and stimulating. It often occurs in challenging but achievable situations, such as starting a new job, planning a wedding or playing sports.

Eustress can help increase performance and promote personal growth.

Distress, on the other hand, is negative stress that is perceived as burdensome and overwhelming. It can be triggered by various factors, such as financial problems, relationship stress, or health concerns. Distress can lead to anxiety, exhaustion, and health problems if it persists over a long period of time.

Eustress is good, motivating stress. Sport has a significant influence on eustress.

Here are some positive effects:

• Increased motivation: Sporting activities can promote feelings of success and satisfaction, leading to an increase in eustress.
• Improved mood: Exercise releases endorphins, known as ‘happiness hormones’, which increase overall well-being.
• Achieving goals: Setting and achieving fitness goals can give you a strong sense of fulfilment, which creates eustress.
• Social interaction: Group sports promote social contact, which offers positive emotional experiences and support. Doing sports activities together with your partner leads to new, unexpected feelings of happiness in your relationship.
• Stress reduction: Regular physical activity can help reduce everyday stress and strengthen resilience to challenges.

Distress is negative, stressful stress. Sport can have both positive and negative effects on distress. Here are some ways in which sport can influence distress:

• Overtraining: Training too intensely or too frequently can lead to physical and mental exhaustion, which can trigger distress.
• Pressure and expectations: Pressure to perform, whether in competition or personal training, can cause stress and anxiety, especially when one’s own expectations are not met.
• Injuries: Sports injuries can cause not only physical pain but also psychological stress, especially if they limit athletic activity.
• Time management: Trying to fit exercise into a busy schedule can cause additional stress, especially if it conflicts with other commitments.
• Comparison with others: Comparing yourself to other athletes can lead to feelings of inadequacy and thus to distress.

Overall, the impact of exercise on distress depends heavily on the individual’s approach and expectations, goals, and the balance between exertion and recovery.

Adrenal function and sport

Stress regulation mainly takes place in the adrenal glands. The adrenal glands regulate stress primarily through the production of hormones, in particular cortisol, which is known as the stress hormone. Here is an overview of the process:

• Activation of the hypothalamic-pituitary-adrenal axis (HPA axis): When stressed, the hypothalamus is activated, releasing corticotropin-releasing hormone (CRH).
• Stimulation of the pituitary gland: CRH stimulates the pituitary gland to produce adrenocorticotropic hormone (ACTH).
• Hormone production in the adrenal gland: ACTH stimulates the adrenal cortex to produce and release cortisol. Cortisol has many functions, including raising blood sugar levels, suppressing the immune system and regulating metabolism.
• Feedback mechanism: Elevated cortisol levels send signals to the hypothalamus and pituitary gland to dampen the production of CRH and ACTH, which is a negative feedback mechanism.

These hormones help the body respond to stress by providing energy and regulating physical responses to stressors. However, prolonged activation of this axis can have negative health effects, such as anxiety, sleep disturbances, and other stress-related disorders.

The adrenal medulla, the inner part of the adrenal gland, plays a crucial role in stress regulation through the production of catecholamines, particularly adrenalin and noradrenaline. Here are the key aspects of stress regulation by the adrenal medulla:

• Activation of the sympathetic nervous system: Acute stress activates the sympathetic nervous system. This often occurs in response to a threat or stressor.
• Release of catecholamines: The adrenal medulla responds to the activation of the sympathetic nervous system by releasing adrenalin and noradrenaline into the blood.
• Physiological effects: These hormones cause a series of physiological changes in the body to prepare it for a ‘fight-or-flight’ response:
  • Increase in heart rate and blood pressure
  • Dilatation of the airways to improve oxygen uptake
  • Increase in glucose release from the liver to provide energy
  • Increase in blood flow to the muscles
• Rapid response to stress: Unlike the HPA axis, which triggers a slow but long-lasting response to stress, the release of catecholamines by the adrenal medulla enables a rapid response to acute stressors.

These mechanisms are essential for survival in dangerous situations, but can lead to health problems in cases of chronic stress, such as cardiovascular diseases and anxiety disorders.

The thyroid gland and sport (with special consideration given to Hashimoto’s autoimmune thyroiditis)

The thyroid gland plays a crucial role in athletic performance, as it produces hormones that influence metabolism, energy levels and general physical function. Here are some important aspects:

• Metabolism regulation: Thyroid hormones (thyroxine and triiodothyronine) regulate metabolism. Sufficient production of these hormones is important for energy production from nutrients, which is essential for sporting activities.
• Energy levels: A well-functioning thyroid gland contributes to stable energy levels. Low thyroid hormones (hypothyroidism) can lead to fatigue and reduced performance, while hyperactivity (hyperthyroidism) can lead to increased nervousness and faster fatigue.
• Muscle strength and growth: Thyroid hormones also influence muscle metabolism and protein synthesis. An imbalance can negatively affect muscle strength and growth.
• Endurance: Optimal thyroid function is important for endurance performance.Low hormone levels can reduce endurance and prolong recovery after exercise.
• Body weight: Thyroid hormones play a role in regulating body weight. An imbalance can lead to weight gain or loss, which can also affect athletic performance.

Overall, the thyroid gland has a significant impact on athletic performance, and an imbalance can impair both physical performance and general well-being.

Conversely, the distress mentioned above also has a negative effect on thyroid function. For example, Hashimoto’s disease is caused by negative stress. In most cases, patients develop thyroid autoantibodies when they are dissatisfied with their athletic performance or when they fail to achieve the athletic goals they have set for themselves. This leads to a vicious cycle that can result in permanent, irreversible hypothyroidism. If you intervene early and have your thyroid function checked by a doctor, Hashimoto’s disease can be detected at a stage when only the thyroid antibodies are elevated. This is the phase in which such changes are reversible and do not lead to irreversible hypothyroidism.

Hormonal abuse to enhance performance

Testosterone is often used to enhance performance. This is doping and therefore obsolete in competitive sports. Even in amateur athletes, it can lead to life-threatening complications depending on the dose:

• Strokes: The risk of strokes increases due to the development of polycythaemia. The blood becomes too thick, and haemoglobin and haematocrit levels rise. Especially in cases of high fluid loss, this can lead to blindness or hemiplegia, depending on which vessel is affected.
• Thrombosis: The risk of thrombosis also increases with the start of treatment due to possible polycythaemia. In rare cases, this can lead to pulmonary embolism, which in the worst case can be fatal.
• In men, prostate hypertrophy occurs, leading to frequent urination, nocturnal urination and other problems with bladder function and sexual function.

Growth hormone is used to build muscle. This can also lead to muscle growth in the heart muscle. Cardiomyopathy is often associated with reduced performance and can lead to cardiac arrhythmia and death. The use of growth hormone (HGH) in athletes can have various side effects and risks. Here are some of the most common:

• Acromegaly: Long-term use can lead to acromegaly, a condition characterised by excessive growth of bones and soft tissues, especially in the face, hands and feet.
• Joint pain and swelling: HGH can cause pain, swelling and stiffness in the joints, especially on the face, hands and feet.
• Insulin resistance: The use of growth hormone can reduce insulin sensitivity, which increases the risk of type 2 diabetes.
• Heart problems: HGH can increase the risk of cardiovascular disease, especially when used in high doses.
• Oedema: Fluid retention in the tissues can occur, leading to swelling in various areas of the body.
• High blood pressure: Growth hormone can lead to high blood pressure, which further increases the risk of heart problems.
• Increased risk of carcinoma: There is evidence that the use of HGH may increase the risk of tumour formation, especially in people who already have a predisposition to cancer.
• Psychological effects: Although less common, psychological side effects such as mood swings and anxiety may also occur.

Overall, the side effects of growth hormone therapy can be significant and should be carefully weighed, especially in terms of the risks compared to the potential benefits in sport.

Steroids are synthetically produced and used as anabolic agents. The use of anabolic steroids can lead to a number of dose-dependent side effects and complications in athletes. Here are some of the most common:

• Hormonal changes: Steroids can disrupt the natural hormone system, which can lead to a reduction in the body’s own testosterone production. This can lead to infertility and sexual dysfunction.
• Cardiovascular problems: Steroid use can increase the risk of heart disease, high blood pressure and strokes. They can also have a negative effect on cholesterol levels.
• Liver problems: Oral steroids can cause liver damage or disease, including liver cysts and tumours.
• Psychological effects: Steroid use can lead to mood swings, aggression, anxiety and depression. Some users also experience ‘roid rage’, a state of extreme irritability and aggression.
• Skin problems: These include acne, oily skin and changes in skin colour. In addition, the use of steroids can lead to stretch marks.
• Bone and joint problems: Steroids can increase the risk of joint pain, tendon injuries and osteoporosis.
• Aesthetic changes: Men may experience gynaecomastia (breast enlargement), while women may develop male secondary sexual characteristics such as a deeper voice and increased hair growth.
• Dependence: Long-term use of steroids can lead to psychological and physical dependence, making it difficult to stop therapy.

These side effects and complications clearly demonstrate that steroid therapy, especially for performance-enhancing purposes, is associated with significant risks.

Vitamin D – Hormone & Sport

Vitamin D is an essential hormone that plays a crucial role in the human body, especially in terms of health and fitness. It is mainly synthesised by sunlight on the skin, but can also be absorbed through food. However, dietary intake alone is insufficient to meet daily requirements.

Vitamin D is particularly important in relation to sport, as it supports bone health by promoting calcium absorption and regulating bone mineralisation. An adequate supply of vitamin D can reduce the risk of injuries such as stress fractures or bone oedema and improve muscle strength. Studies show that athletes with optimal vitamin D levels often perform better and recover faster.

In addition, the vitamin D hormone influences the immune system, which is important for athletes as intensive training sessions can put strain on the immune system. A well-functioning immune system helps to prevent illness and injury.

Vitamin D also reduces the risk of cancer in some people. The gut microbiome (gut bacteria) plays a crucial role in this. Overall, vitamin D is very important for athletes, and targeted supplementation or sufficient sun exposure can help optimise athletic performance and overall health.