On TikTok and Instagram, videos that promise more biceps by “boosting” the
testosterone with zinc or magnesium number in the thousands. Supplements, even steroids, are presented as magical shortcuts to gaining weight. muscle mass. Biology tells a much less spectacular story.
Testosterone remains a key hormone, but it never works alone. “There are two key factors“, explains Professor Leigh Breen, specialist in muscle physiology at the University of Leicester, in the pages of the Guardian. “The amount of testosterone in your body, and the number of androgen receptors in your muscles“. Simply put, without sufficient “electrical outlets” in the muscle, even decent hormone levels don’t translate into huge arms.
Testosterone, androgen receptors and muscle: the decisive duo
Androgen receptors are these little “docking sites” that allow testosterone to activate muscle growth. Their number depends mainly on genetics, but their effectiveness changes with lifestyle. Regular resistance training increases the expression of these receptors and makes normal hormone levels much more effective.
For the vast majority of adults, the problem does not come from a “lack” of testosterone, but from this muscular response. “For most of our adult lives, natural fluctuations, or changes we see with exercise and diet, are subtle“, says Leigh Breen in The Guardian. Physiology studies also show that small spikes in testosterone after a session don’t really predict long-term strength or volume gains.
When Testosterone Really Changes Everything… and When It Changes Almost Nothing
At the extremes, the hormone can become decisive. THE
anabolic steroids flood the body with testosterone at levels far above natural. “The effect on muscle mass is considerable“, says Leigh Breen. “There have been cases of muscle gain without training“These practices are, however, accompanied by cardiovascular and hormonal risks widely described by sports doctors.
Anabolic steroids also cause various side effects, whether psychological, such as mood changes, increased aggression, or irritability, or physical, such as acne, masculinization in women, infertility, decreased natural testosterone production, and gynecomastia in men.
Conversely, a severe deficit, such as hypogonadism in certain elderly men, leads to muscle wasting and fatigue. Testosterone replacement therapy can then help, under strict medical supervision. It is estimated that total testosterone declines on average by around 1 to 2% per year after the age of 30, but many symptoms attributed to this decline relate more to a sedentary lifestyle and fat gain.
Building muscle: the real levers beyond testosterone
For someone whose testosterone is within the norm, the major determinants of muscle gain remain the same: progressive overload in bodybuilding, sufficient protein, appropriate calories, correct sleep. Experts emphasize this trio, with a simple keyword: regularity. The training itself stimulates androgen receptors and improves the use of testosterone already present.
ZMA-type “boosters” often disappoint. A controlled study published on the scientific platform PubMed Central did not find a significant increase in testosterone or better muscle gains in well-nourished athletes supplemented with zinc and magnesium compared to a placebo. For most practitioners, focusing on the testosterone figure during a blood test therefore diverts attention from what really changes the physique: training, diet and lifestyle.