How physical load affects the hormonal system: testosterone, cortisol, growth hormone, insulin, and their significance for adaptation.

Hormones are chemical messengers that regulate virtually all physiological processes. Physical load is one of the strongest stimulators of the endocrine system.
The main anabolic hormone. Strength training acutely raises testosterone (depending on volume and intensity). Chronic endurance load can reduce testosterone levels.
Main catabolic/stress hormone. Increases proportionally to load duration. Long (>90 min.) or very intense training raises cortisol 2–5×. Chronic elevation is a marker of overtraining.
Secreted from the pituitary gland in a pulsatile manner. Intense load (especially HIIT, sprints, heavy athletics) raises GH 5–10×. The greatest secretion is during sleep.
Insulin-like growth factor — a mediator between GH and tissue growth. Produced in the liver and locally in muscles (MGF — mechano growth factor). Strength training increases IGF-1 expression in muscles.
| Hormone | Strength Training | Endurance Training | HIIT | Overtraining |
|---|---|---|---|---|
| Testosterone | ↑ 10–30% acutely | ↔ or ↓ (in long distances) | ↑ 10–20% | ↓ (chronic) |
| Cortisol | ↑ 20–100% | ↑ 50–300% (depending on duration) | ↑ 50–150% | ↑ chronic ↑↑ |
| T/C ratio | ↑ or ↔ | ↓ (especially >2 h) | ↔ | ↓ (important overtraining marker) |
| Growth hormone | ↑ 5–10× | ↑ 2–5× | ↑ 5–15× | ↓ (reduced pulsatility) |
| IGF-1 | ↔ or ↑ (chronic adaptation) | ↔ or ↓ (with energy deficit) | ↔ | ↓ |
| Catecholamines (A, NA) | ↑ 5–20× | ↑ 2–10× | ↑ 10–30× | ↓ response (exhaustion) |
| Insulin | ↓ during load, ↑ after (sensitivity) | ↓ during load | ↓ | ↔ or resistance (chronic) |
Hormonal balance is critical for both results and health. How to avoid hormonal imbalance:
Post-Workout Nutrition: within 30–60 min. after exercise, consume protein + carbohydrates in a ratio of 1:3–4. This is the so-called “anabolic window”, when muscles most efficiently absorb nutrients.
Properly selected sports supplements can significantly improve performance, recovery and overall well-being. Below is a table of the main supplements:
| Supplement | Purpose | Recommended Dose | When to Take |
|---|---|---|---|
| Whey protein | Muscle recovery and growth | 20–40 g after training | After training / between meals |
| Creatine | Increasing strength and explosive power | 5 g per day | At any time, consistently |
| Beta-alanine | Delays muscle fatigue | 3–6 g per day | Pre-Workout |
| Omega-3 | Reducing inflammation, heart health | 1–3 g EPA/DHA | With food |
| Magnesium | Muscle relaxation, sleep | 300–400 mg | In the evening before sleep |
| Vitamin D3 | Bone health, immunity | 2000–4000 IU | With food (in the morning) |
Injury prevention is an integral part of any sports program. Follow these principles:
Record not only loads but also subjective feelings: sleep quality, fatigue level, appetite. This helps detect signs of overtraining early.
Blood tests 1–2 times per year: complete blood count, ferritin, vitamin D, testosterone/cortisol, thyroid hormones. Prevention is cheaper than treatment.
There is no single perfect training plan for the whole year. Alternate periods of intensity, volume, and specificity. Classic cycle: 3–4 sav. of load increase, 1 sav. of recovery.
What works for an Olympic champion will not necessarily work for you. Genetics, lifestyle, stress, nutrition — everything is individual. Experiment and monitor your body’s response.
Consult a sports medicine physician or a certified coach before starting a new program.
Q: Does sport really strengthen immunity?
A: Regular moderate-intensity training reduces the risk of upper respiratory tract infections (URTIs). However, intense competitions or ultra-endurance workloads temporarily (3–72 h) weaken immunity — this is called the “open window” period. Important: rest, nutrition, and sleep after intense workloads.
Q: How can I find out whether my hormone balance is good?
A: Key markers: testosterone/cortisol (T/C) ratio, sex hormone-binding globulin (SHBG) level, free testosterone amount. Athletes are recommended to get tested 1–2× per year. Warning signs: chronic fatigue, reduced libido, sleep disturbances, mood swings.
The information provided in this tool is based on scientific literature in sports physiology. We recommend the following authoritative sources for further study:
⚠️ Disclaimer: This information is for educational purposes. For individual health concerns, always consult a sports medicine specialist.