Osteoporosis in men in athletes: causes and links with training load and pharmacology

Osteoporosis is commonly considered a 'female' disease, yet approximately one in five men over 50, by many estimates, suffers an osteoporotic fracture. Among athletes, low bone density occurs not only in veterans. The editorial team examines how the type of sport, nutrition and pharmacology, in particular hormonal drugs, affect men's bones.

How bone is built and destroyed in men

Bone is a living tissue that is constantly renewed: osteoclasts break down old bone matter, and osteoblasts build new. The balance of these processes determines bone mass. Peak bone mass is reached at about 25-30 years, and then gradually declines.

Men have larger bone sizes and higher peak mass, so osteoporosis develops in them later. However, after hip fractures the mortality among men is higher than among women, which makes the problem no less serious.

The key regulators of bone metabolism in men are the sex hormones. A study by Finkelstein and co-authors (2016) showed that it is precisely estradiol, which is formed from testosterone under the action of aromatase, that plays the main role in preventing bone resorption in men, while testosterone mainly affects the size and strength of bones.

So for a man's bones not only testosterone is important, but the whole hormonal chain: pituitary gland, testicles, aromatization, sufficient levels of calcium, vitamin D, protein and energy.

The type of sport matters

Bone responds to mechanical load: impact and multidirectional loads (jumps, running, team sports, strength exercises) stimulate bone tissue formation. That is why players of team sports, weightlifters and gymnasts usually have higher bone mineral density.

In contrast, sports without impact loads - cycling, swimming - stimulate bone little. Studies of road cyclists have repeatedly found reduced density of the spine and hip in them, even at a young age, especially with large training volumes.

Long-distance running occupies an intermediate place: there is an impact load, but the combination of a large volume with low body mass and insufficient nutrition can outweigh the positive effect.

That is why the editorial team stresses: it is useful for swimmers and cyclists to include strength and jumping exercises in the training plan - this is a generally accepted approach to maintaining bone health.

Energy deficiency and REDs in men

The concept of the 'female athlete triad' was expanded to REDs - the syndrome of relative energy deficiency in sport, and the 2023 IOC consensus clearly states that it also occurs in men. Insufficient energy intake disrupts the hormonal balance, in particular lowers testosterone, and worsens the condition of bones.

Tenforde and co-authors (2016) described parallels between the triad in women and the condition of male athletes: low energy availability, reduced bone density and hormonal disturbances manifested in a decrease in testosterone.

• prolonged calorie deficiency and low energy availability;
• low testosterone against a background of depletion;
• stress fractures, especially of trabecular bones;
• insufficient intake of calcium, protein and vitamin D.

In the risk group are long-distance runners, cyclists, jockeys, combat and aesthetic sport athletes, as well as bodybuilders during prolonged preparation for competitions, when the calorie deficit persists for months.

Manifestations can be stress fractures, frequent injuries, decreased libido, fatigue, worsening results. Unlike women, men do not have such a visible marker as menstrual cycle disturbance, so the problem is often missed.

Pharmacology: hormones that harm bones

Anabolic steroids during use suppress one's own pituitary-testicular axis. After discontinuation, many men develop prolonged hypogonadism, described in the work of Rahnema and co-authors (2014). Low testosterone and estradiol during this period are a factor in the loss of bone mass.

Aromatase inhibitors, which are used in the sporting environment to lower estradiol, are particularly problematic from the standpoint of bones. Studies in men show that it is precisely estradiol that restrains bone resorption, so its excessive suppression can accelerate its loss. The medical prescription of these drugs is primarily the treatment of breast cancer.

Thyroid hormones (in particular T3), which are used non-medically for 'fat burning', in excess accelerate bone metabolism and the loss of bone mass. Thyrotoxicosis is a known secondary factor of osteoporosis. Besides bones, an excess of hormones threatens the heart through arrhythmias.

Systemic glucocorticoids are the most common drug cause of osteoporosis. Even moderate doses over several months increase the risk of fractures. They are used only for medical indications, and with a long course the doctor assesses the need for bone protection.

Other secondary causes

In men, according to the 2012 Endocrine Society guidelines, secondary causes of osteoporosis are found often. Among them are alcohol in large quantities, smoking, hypogonadism of any origin, celiac disease and other intestinal diseases, chronic kidney and liver disease.

Among drugs, besides glucocorticoids, attention is drawn to anticonvulsants, proton pump inhibitors with long-term use, androgen-deprivation therapy in prostate cancer, some antidepressants. The decision on such drugs is always made by a doctor.

Hyperparathyroidism, vitamin D deficiency, multiple myeloma and hypercortisolism are conditions that a doctor rules out when low bone density is found in a man, especially a young one.

So osteoporosis in a male athlete should never be considered 'just a consequence of training': almost always there is a specific cause behind it that can be found and corrected.

Editorial conclusions

Osteoporosis in male athletes is a real problem that is not limited to age. The most important factors are the type of load, energy deficiency and hormonal status.

A special threat to bones is posed by the non-medical use of hormonal drugs: hypogonadism after AAS withdrawal, suppression of estradiol by aromatase inhibitors, an excess of thyroid hormones.

Impact and strength exercises, sufficient energy, protein, calcium and vitamin D are the basis of prevention, and when low bone density is found, a secondary cause must be sought.

We also advise reading our articles on the prevention and diagnosis of osteoporosis in men, on vitamin D deficiency and on restoration of the hormonal system.

References

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