Hormones and training: what the Sports Hormone Profile, cortisol and IGF-1 measure

Two athletes follow the same plan for twelve weeks. One finishes the block stronger; the other feels heavier, sleeps badly and loses interest in sessions. Plenty can explain the difference, from food and sleep to stress at work. Hormones are part of that story, because training changes them and they, in turn, influence how the body adapts.

This guide looks at hormones and training through three items in the BPR catalogue: the Sports Hormone Profile, Cortisol and IGF-1 (Somatomedin), all processed by London Medical Laboratory (LML).

How hormones and training interact

Physical activity has a strong effect on the neuroendocrine system. A 2024 review describes how the hormonal response to exercise is shaped by the person (genetics, age, sex, daily biological rhythms, nutrition, training level, medicines and supplements) and by the exercise itself (type, intensity, duration and environment) (Mennitti et al., 2024). That is why the same session can produce different results in two people, and why a single reading means little without context.

Energy matters too. The 2023 International Olympic Committee consensus on Relative Energy Deficiency in Sport explains that a long mismatch between the energy an athlete eats and the energy training demands can disturb several hormonal systems, among other effects (Mountjoy et al., 2023).

The Sports Hormone Profile

The LML describes this profile as covering the widest range of hormones and systems affected by fitness activity that can be measured in a blood test. It includes:

• Androgens: total testosterone, free testosterone, SHBG (the protein that carries sex hormones), DHEA-S and the free androgen index.
• Other reproductive hormones: oestradiol, LH, FSH and prolactin.
• Thyroid: TSH and free T4. The LML notes that when the thyroid is not working well, energy levels suffer.
• Liver function: ALT, AST, GGT, ALP, bilirubin, albumin and total protein. The liver processes most of what we eat and take, including supplements.

The LML points out that these hormones matter for both men and women, in different concentrations, and suggests the profile for people who want to follow the effect of supplements or who feel they are not responding to exercise as expected. For this profile the LML asks for a venous sample.

Cortisol

Cortisol is a hormone released in response to stress. According to the LML, it helps regulate metabolism, immune function and blood pressure. Exercise is a form of stress, so cortisol naturally changes around training (Mennitti et al., 2024).

A few practical points from the LML text are worth knowing before testing:

• in women, levels can vary across the menstrual cycle;
• some medicines, such as oral contraceptives, can affect cortisol and should be mentioned when results are read.

Because biological rhythms shape hormone levels, it helps to collect at a similar time of day each time you test, so that two results can actually be compared.

IGF-1 (Somatomedin)

IGF-1, insulin-like growth factor 1, is produced mainly by the liver in response to growth hormone. The LML explains that the test is used to evaluate growth disorders and to follow growth hormone therapy, among other uses. In a sports setting it is sometimes requested alongside other hormones when a clinician wants a fuller view of the growth hormone axis.

The LML asks for this sample to be sent to the laboratory without delay and handled frozen, so the collection route matters. An LML collection point is usually the most practical option.

Reading hormone results with care

It is tempting to treat a hormone panel as a scoreboard. The joint consensus statement of the European College of Sport Science and the American College of Sports Medicine on overtraining is clear that several markers, hormones included, are in use, but none meets all the criteria to be generally accepted on its own (Meeusen et al., 2013). The same statement stresses ruling out other factors first, such as too little energy, carbohydrate or protein, and low iron or magnesium.

In practice, hormone results are most useful when they are:

• compared with your own earlier results rather than only with a reference range;
• taken under similar conditions each time: time of day, rest before the sample, recent training load;
• read together with how you feel, how you perform and what you eat.

When to test in a training cycle

As general guidance, many athletes test at the start and at the end of each training phase. A result at the start sets a baseline; a result at the end shows how the body handled the block. Testing the morning after a very hard session tends to blur the picture. Talk to a health professional about the timing that fits your sport, your season and any medicines or supplements you use.

How collection works

Samples are collected and analysed by the LML; BPR Clinic does not take samples. Depending on the test, you can use a home kit, visit an LML collection point (search by postcode) or book a phlebotomist at home. For IGF-1 and the Sports Hormone Profile, a venous sample is needed. These tests are in the BPR catalogue, and you can send questions through the app, the form on our website or [email protected].

Frequently asked questions

Is the Sports Hormone Profile only for men? No. The LML notes that the hormones it measures are important for both men and women, in different concentrations.

Does the time of day matter for cortisol? Hormones follow biological rhythms, so collecting at a similar time each time makes results easier to compare. Follow the instructions that come with your order.

Can a hormone test tell me I am overtrained? Not on its own. The consensus on overtraining states that no single marker meets all the criteria, so results are read alongside performance, training load and symptoms.

References

1. Mennitti C et al. Biomolecules. 2024;14(11):1418. PMID 39595594
2. Meeusen R et al. Med Sci Sports Exerc. 2013;45(1):186-205. PMID 23247672
3. Mountjoy M et al. Br J Sports Med. 2023;57(17):1073-1097. PMID 37752011