Here is the thing nobody tells you about testosterone and cycling after 40. The decline is real. The anxiety about it is usually worse than the decline itself.
You have probably read the threads. The forum posts from blokes who got their blood work back and panicked. The Instagram ads promising to "restore youthful vitality" with a pill that costs forty quid a month. The podcast clips where someone mentions TRT and the comments section turns into a war zone.
Let me break this down properly. Because there is good science on this topic, there are clear things you can do about it, and there is a significant amount of noise that is making masters cyclists more anxious and less informed than they need to be.
This is not scaremongering. It is not a sales pitch. It is what the evidence actually says.
The Numbers: What Happens to Testosterone After 30
Testosterone production peaks somewhere in your mid-twenties. After roughly age 30, total testosterone declines at about 1-2% per year in most men. The data on this is solid — the Massachusetts Male Aging Study, the European Male Ageing Study, and the Baltimore Longitudinal Study of Aging all converge on similar numbers.
Let me be really clear about this: 1-2% per year does not feel like much. And for the first decade, it is not. The compounding is what gets you.
By 40, you are operating on roughly 10-20% less testosterone than your mid-twenties peak. By 50, that number is 20-35%. By 60, it can be 30-50%. These are averages. Individual variation is enormous. Some men at 55 have testosterone levels that would be unremarkable in a 35-year-old. Others at 45 are already clinically low.
The important thing is trajectory, not a single number. A blood test is a photograph. What you need is a time-lapse.
Here is where it gets really interesting. The decline is not linear in every man. Major life stressors, illness, weight gain, chronic sleep deprivation, and — this is particularly relevant for our audience — sustained overtraining can accelerate the curve. The 1-2% average includes men who are sleeping well, maintaining healthy body composition, and managing stress. If you are doing none of those things, the decline is faster.
Total vs Free Testosterone: The Distinction That Changes Everything
If you have had blood work done and the doctor told you your testosterone was "within range," you need to understand what they probably measured and what they almost certainly did not.
Most standard panels measure total testosterone. That is the headline number. In the UK, the reference range is typically 8-29 nmol/L. In the US, it is 300-1000 ng/dL. If your number falls anywhere inside that window, the system marks you as normal and moves on.
The problem: total testosterone includes everything — the testosterone bound to sex hormone-binding globulin (SHBG), the testosterone bound to albumin, and the small fraction that is actually free and biologically active. Only about 2-3% of your total testosterone is free testosterone. That free fraction is the testosterone your muscles, bones, and brain can actually use.
And here is the kicker. SHBG increases with age. So your total testosterone might look reasonable on paper while the fraction that is actually available to your tissues has been quietly declining faster than the headline number suggests.
Dr Mark Gordon, the neuroendocrinologist who appeared on the podcast, puts it bluntly: total testosterone without free testosterone is a junk metric. You could have a total level of 18 nmol/L — perfectly respectable — and a free testosterone sitting in the bottom 10% of the reference range. Functionally, you are underfunded.
For a detailed breakdown of Gordon's 50th-to-75th percentile target for free testosterone and the crash-related hormonal damage he links to cumulative cycling trauma, that conversation is worth your time separately. This guide is about the broader picture.
The takeaway: when you get blood work, insist on free testosterone. Not just total. If your doctor only orders total testosterone and tells you everything is fine, you have half the picture.
What Training Can Do for Testosterone — And What It Cannot
Training is hormonal medicine. That is not hyperbole. Different types of training produce different hormonal responses, and understanding which levers you are actually pulling matters.
What training does well
High-intensity intervals produce an acute testosterone spike. The research from Hackney and others shows that short, intense efforts — the kind of session where you are properly suffering for 3-5 minutes and then recovering — trigger a temporary but meaningful increase in testosterone. This is one of the reasons structured interval work matters for masters cyclists beyond the obvious power and VO2max benefits. You are sending a hormonal signal.
Resistance training with meaningful load stimulates testosterone production acutely and supports the anabolic signalling pathways that preserve muscle mass. Two sessions a week of cycling-specific strength work — split squats, hip hinges, single-leg work, hip thrusts, controlled pressing — is not just about preventing sarcopenia. It is part of your hormonal strategy.
Zone 2 work at sensible volumes supports the broader metabolic environment without driving the chronic stress response that suppresses testosterone. The base work matters. But volume without recovery is not base training. It is overreaching with a heart rate monitor on.
What training cannot do
Training will not raise your testosterone above your genetic ceiling. A well-structured programme can help you sit at the top of your natural range. It cannot put you outside it. No amount of interval work is going to take a 48-year-old from 12 nmol/L total testosterone to 25 nmol/L. That is not how the physiology works.
Training also cannot compensate for the other factors that are dragging your testosterone down. If you are sleeping five hours a night, chronically underfuelling, carrying 25% body fat, and working a high-stress job, the best training plan in the world is writing cheques your hormonal system cannot cash.
The Overtraining Trap: Cortisol, Testosterone, and the Spiral
This is the section that should matter most to the audience reading this. Because the cyclists most likely to be worried about testosterone are often the same ones whose training habits are actively suppressing it.
Here is how the spiral works.
You train hard. Cortisol rises — that is the normal acute stress response. You recover. Cortisol drops. Testosterone remains at its baseline. System working as intended.
Now add insufficient recovery. You train hard again before cortisol has cleared. Cortisol stays elevated. Chronically elevated cortisol suppresses the hypothalamic-pituitary-gonadal axis — the signalling chain that drives testosterone production. Your body reads the sustained stress as a signal that survival is the priority, not reproduction or muscle building. Testosterone drops. Recovery slows. You feel flat. You think the answer is more training. You train harder. Cortisol goes higher. Testosterone drops further.
This is not theoretical. Hackney's research on the "exercise-hypogonadal male condition" describes exactly this pattern in endurance athletes who sustain high training loads without adequate recovery. It is particularly common in masters cyclists who are trying to train like they did at 30 without acknowledging that recovery capacity has changed.
The fix is not a supplement. It is not a pill. It is structure.
Two truly hard sessions per week with proper recovery between them will produce better hormonal outcomes than four hard sessions crammed into seven days. The polarised model that Stephen Seiler's research supports is not just better for fitness. It is better for your hormones.
If you are a masters cyclist doing more than two high-intensity sessions per week and wondering why you feel flat, tired, and unmotivated, the first place to look is not your testosterone level. It is your training structure.
TRT and Sport: The Conversation Nobody Wants to Have Honestly
Let me be really clear about this, because the internet handles this topic badly.
The regulatory position
Testosterone replacement therapy is prohibited under the World Anti-Doping Agency (WADA) code. It is on the prohibited list at all times — in competition and out of competition. This applies to all athletes who compete under a WADA-compliant federation.
For cycling, that means UCI rules, British Cycling rules, Cycling Ireland rules, UKAD jurisdiction, and every national federation that operates under the UCI umbrella.
Masters racing is included. There is no age exemption. There is no therapeutic use exemption (TUE) for age-related testosterone decline. WADA and UKAD are explicit on this point: the natural decline of testosterone with age does not constitute a medical condition that warrants a TUE. If you are on TRT and you hold a racing licence, you are in breach of anti-doping rules. Full stop.
If you are caught, the standard sanction is a four-year ban. For masters racing, that is often a career-ending penalty.
The moral grey area
Here is where it gets complicated, and I am not going to pretend it is not.
A 52-year-old man goes to his doctor. His testosterone is clinically low — below 8 nmol/L. He has symptoms: persistent fatigue, brain fog, loss of motivation, declining bone density, low libido. His doctor prescribes TRT. It is a legitimate medical intervention for a genuine clinical condition.
That same man also races in his local masters league on Saturdays.
Under the current rules, he has to choose. Treat the medical condition and stop racing, or keep racing and live with the symptoms. There is no middle ground.
Is that fair? That depends on who you ask. The anti-doping argument is clear: exogenous testosterone is a performance-enhancing substance regardless of the reason it is being taken, and allowing TUEs for age-related decline would open a door that cannot be closed. The counter-argument is equally clear: you are asking men to choose between their health and their sport, and that is a poor choice to force on anyone.
I am not going to tell you what to think about this. But I am going to tell you what the rules are, because too many people in the masters cycling world either do not know or choose to ignore them.
If you do not race
If you have no racing licence, no federation membership, and no intention of competing in sanctioned events, TRT is a medical decision between you and your doctor. Period. Get proper blood work. Get a proper diagnosis. Work with an endocrinologist, not an Instagram clinic. Make the decision based on evidence, not anxiety.
The Lifestyle Factors That Actually Matter
Before you spend a single penny on supplements, clinics, or blood work, audit these four areas. They are less exciting than a hormone panel. They are also more effective than anything you can buy over the counter.
Sleep
Sleep is the single most powerful natural testosterone intervention available to you. This is not opinion. This is what the research says.
Leproult and Van Cauter's 2011 study showed that restricting sleep to five hours per night for one week reduced testosterone levels by 10-15% in young, healthy men. That is a bigger drop than most men experience from an entire decade of ageing.
The specifics matter. Testosterone production peaks during deep sleep, particularly in the first half of the night. The quality markers you should care about:
- Duration: 7-9 hours. Not 6. Not "I function fine on 6." The data does not support that for hormonal health.
- Timing: The majority of your sleep before midnight matters because of the alignment with circadian cortisol and testosterone rhythms. A midnight-to-8am block is not the same as a 10pm-to-6am block, even though the hours are identical.
- Continuity: Fragmented sleep — waking multiple times — disrupts the slow-wave sleep phases where testosterone production is highest. If you are waking up three times a night, that is worth investigating before anything else.
- Environment: Cool room (16-18 degrees), dark, no screens in the last hour. You know all this. The question is whether you are actually doing it.
Body fat percentage
This one is straightforward but important. Adipose tissue contains the enzyme aromatase, which converts testosterone to oestradiol (a form of oestrogen). Higher body fat means higher aromatase activity, which means more of your testosterone is being converted rather than used.
The research from Zumoff and others shows a clear inverse relationship between body fat percentage and testosterone in men. Above roughly 20% body fat, the conversion rate becomes meaningful enough to shift the balance.
The target for most masters cyclists: 15-18% body fat. Not 10%. Not race-weight lean-ness year-round. A sustainable, maintainable body composition that keeps aromatase activity in check without the hormonal disruption that comes from being too lean for too long.
And here is the important caveat: crash dieting to get there will make the problem worse, not better. Severe caloric restriction suppresses testosterone directly. The path is steady, moderate caloric management over months. Not a six-week cut.
Stress management
Chronic psychological stress elevates cortisol through the same pathway as overtraining. The hypothalamic-pituitary-adrenal axis does not distinguish between work stress, relationship stress, financial stress, and training stress. It all lands on the same ledger.
The interventions that have evidence behind them for cortisol management: regular meditation (even 10-15 minutes, three times per week — Gordon cites research showing this can halve cortisol levels), time in nature, social connection, and — this is the unsexy one — saying no to things. An overscheduled life is a cortisol-producing life.
Alcohol
This is the one nobody wants to hear. Alcohol suppresses testosterone production acutely and, at higher intake levels, chronically. The mechanism is direct — ethanol inhibits the enzymes involved in testosterone synthesis in the Leydig cells of the testes.
You do not have to become teetotal. But if you are having more than a few drinks per week and wondering why your recovery is poor and your energy is flat, the alcohol is not helping. Two to three drinks per week appears to have minimal impact. Beyond that, the dose-response curve steepens.
Blood Testing: What to Ask For, When to Test, What It Means
If you have read this far and you are thinking about getting tested, here is how to do it properly.
The panel
A comprehensive hormonal panel for a masters cyclist should include:
- Total testosterone — the headline number. Context, not the full story.
- Free testosterone — the number that matters for function. Calculated or measured directly.
- SHBG (sex hormone-binding globulin) — the protein that binds testosterone and makes it unavailable. Rising SHBG with age is a major reason free testosterone declines faster than total.
- LH (luteinising hormone) — the signal from the pituitary that tells the testes to produce testosterone. Low LH with low testosterone suggests a central (brain-level) problem. High LH with low testosterone suggests the testes are not responding.
- FSH (follicle-stimulating hormone) — paired with LH, this helps distinguish between primary and secondary hypogonadism.
- Cortisol (morning, fasted) — context for the testosterone number. High cortisol with low testosterone is a different problem from low cortisol with low testosterone.
- DHEA-S — the adrenal precursor hormone. Low DHEA-S in combination with low testosterone and high cortisol paints a picture of adrenal and gonadal suppression.
- Thyroid panel (TSH, free T3, free T4) — thyroid dysfunction presents with symptoms that overlap heavily with low testosterone. You need to rule it out.
- Vitamin D — low vitamin D is associated with lower testosterone, and deficiency is common in the UK and Ireland, particularly in winter.
- Ferritin and full blood count — not directly testosterone-related, but low iron causes fatigue that mimics hormonal problems, and your doctor should be looking at the full picture.
When to test
- Fasting, before 10am. Testosterone follows a circadian rhythm and peaks in the early morning. An afternoon test will give you a lower reading that does not reflect your baseline.
- On a rest day or easy day. Hard training acutely affects testosterone and cortisol. Testing the morning after a threshold session gives you a stressed snapshot, not a baseline.
- Not during illness or acute stress. Both suppress testosterone temporarily. You want a reading that reflects your normal state.
- At least two readings, taken 2-4 weeks apart. A single blood test is a single data point. Testosterone varies day to day. Two readings that tell the same story are diagnostic. One reading on its own is not.
What the numbers mean
In UK labs, total testosterone reference ranges typically run from about 8 to 29 nmol/L. But "within range" is a wide net. There is a significant difference between 9 nmol/L and 22 nmol/L, and both are technically "normal."
The distinction that matters clinically is between low-normal and clinically low.
Clinically low: total testosterone consistently below 8 nmol/L (roughly 230 ng/dL) with symptoms. This is the threshold where most endocrinologists will consider intervention. Below this level, the evidence for negative health outcomes — bone density loss, metabolic risk, cardiovascular risk — becomes strong enough to warrant treatment regardless of whether the patient is an athlete.
Low-normal: total testosterone between 8-12 nmol/L (230-350 ng/dL). This is the grey zone. You are technically within range. You may be symptomatic. The decision about whether to intervene depends on symptoms, free testosterone levels, other blood markers, and the clinical judgement of your doctor. This is not a DIY decision.
Mid-range and above: 15 nmol/L and up. If your free testosterone is proportionally healthy and you have no symptoms, your hormones are probably not your limiting factor. Look at training structure, nutrition, sleep, and stress before assuming the problem is hormonal.
The Supplement Question: What Has Evidence and What Does Not
Let me be really clear about this before we go any further. No legal, over-the-counter supplement will meaningfully raise your testosterone above your natural baseline. If a supplement could do that, it would be on the WADA prohibited list. It is not.
What some supplements can do is help you stop falling below your baseline by correcting deficiencies that are dragging it down.
Vitamin D
The evidence: Pilz et al. (2011) showed that vitamin D supplementation in deficient men increased total testosterone by about 25%. But — and this is critical — the effect was only seen in men who were deficient to begin with. Men with adequate vitamin D levels saw no further increase.
If you live in the UK or Ireland, there is a reasonable chance your vitamin D is low, particularly between October and April. Get it tested. If it is below 75 nmol/L, supplementing with 2000-4000 IU daily through winter is well-supported. If it is already adequate, extra vitamin D will not do anything for your testosterone.
Zinc
Zinc is required for testosterone synthesis. Severe zinc deficiency clearly lowers testosterone, and correcting it restores levels. The Prasad et al. research from the 1990s established this.
The caveat: most men eating a varied diet are not zinc-deficient. Heavy sweating during training can increase zinc losses, which is relevant for cyclists, but outright deficiency is not common. If your diet includes meat, shellfish, dairy, and nuts, you are probably fine. If you eat a restricted diet or suspect you might be low, a blood test is cheap. Supplementing 15-30mg of zinc daily is safe. Mega-dosing is not — high zinc intake suppresses copper absorption and can cause its own problems.
Magnesium
Magnesium is involved in over 300 enzymatic processes, including several related to testosterone production. The Cinar et al. (2011) study found that magnesium supplementation combined with exercise increased free and total testosterone more than exercise alone.
Again, the effect is strongest when correcting a deficiency. Magnesium deficiency is more common than zinc deficiency in athletic populations because it is lost through sweat. If you cramp frequently, sleep poorly, or have a diet low in leafy greens, nuts, and whole grains, magnesium is worth adding. Magnesium glycinate or citrate in the evening (300-400mg) has the added benefit of supporting sleep quality.
What does not work
Tribulus terrestris, fenugreek, D-aspartic acid, boron, and the majority of "testosterone booster" products on the market have either no evidence, weak evidence, or evidence that shows an effect too small to be clinically meaningful. The supplement industry sells hope. The research sells disappointment.
Save your money for blood work and good food.
Putting It All Together: The Practical Framework
If you are a masters cyclist concerned about testosterone, here is the order of operations. Not what the supplement industry wants you to do. What the evidence supports.
Step one: audit your sleep. Before anything else. Seven to nine hours, consistent timing, cool dark room, no screens in the final hour. If you are not doing this, nothing else matters as much.
Step two: audit your training structure. Are you doing more than two high-intensity sessions per week? Are you taking genuine rest days? Is your easy riding actually easy? If your training structure is driving chronic cortisol elevation, your testosterone is paying the price.
Step three: audit your body composition. If you are above 20% body fat, a gradual, moderate reduction to 15-18% will support testosterone through reduced aromatase activity. Do not crash diet. Steady caloric management over months.
Step four: audit your stress load. Work, family, financial, training — it all sits on the same cortisol ledger. Something has to give. Usually it is the thing you are least willing to let go of.
Step five: get blood work. Full panel, fasting, morning, rest day. Two readings minimum. Bring this article's list of markers to your GP and ask for them specifically. Some doctors will push back on testing free testosterone — stand your ground. It is the number that matters.
Step six: address deficiencies. Vitamin D, zinc, magnesium — but only if blood work or strong dietary suspicion suggests you are low. Do not throw supplements at adequate levels.
Step seven: if clinically low, have the medical conversation. With an endocrinologist, not a forum, not an Instagram ad, not a mate who "feels great on it." If your testosterone is consistently below 8 nmol/L with symptoms, that is a medical situation that deserves proper medical attention.
The Bigger Picture
Here is the thing nobody tells you about testosterone and ageing. The cyclists who are still performing well at 55 and 60 did not find a secret supplement or a maverick doctor. They did the boring things consistently for a decade before they had to.
They slept properly. They trained with structure and restraint. They kept their body composition in a sensible range. They managed their stress. They got blood work done and addressed what needed addressing. They did not panic at a number on a page, and they did not ignore genuine signals from their body.
Testosterone matters. It is a real variable in the equation. But it is one variable among many. A cyclist with moderate testosterone who sleeps well, trains smart, recovers properly, and fuels correctly will outperform a cyclist with higher testosterone who does none of those things.
The decline is real. The response to it is in your hands.
If you want to talk about this with other masters cyclists who are navigating the same questions — training structure, blood work interpretation, the balance between performance and health — that is exactly the kind of conversation that happens inside the Roadman Cycling community.