Signs of Low Testosterone in Athletes Over 40 (Men and Women)

If you're an endurance athlete over 40 and your performance has been declining despite consistent training — if recovery is noticeably slower than it was five years ago, if motivation feels flat in a way that's hard to articulate, or if your body composition is shifting in the wrong direction despite no meaningful change in training — there's something that gets dismissed constantly in this age group that deserves a direct conversation.

Everyone tells you it's just aging. That framing needs to be pushed back on — because while testosterone does decline with age, what most masters athletes are actually dealing with is something more specific and more addressable. Conflating the two means missing the part you can actually do something about.

Prefer to watch? The full video is below — or keep reading for the expanded breakdown

First: Testosterone Is Not Just a Men's Issue

Before anything else, the most important misconception to clear up: testosterone is not exclusively a male hormone, and declining testosterone is not exclusively a men's problem.

Testosterone is critical in both men and women. It drives muscle repair, strength and power output, recovery capacity, energy production, and the motivation that gets you out the door to train. When it drops — at any age, in any athlete — performance drops with it. The age-related decline happens in both sexes, though it presents differently, which we'll get into.

This matters because the conversation about testosterone in women — particularly perimenopausal and postmenopausal women — is dramatically understudied and underdiagnosed. If you're a woman reading this and your care team has never mentioned testosterone as part of your hormonal picture, that's the norm rather than the exception. It shouldn't be.

Why the After-40 Picture Is Different

In your 20s and 30s, low testosterone in an athlete is almost always a downstream problem. Overtraining, under-fueling, chronic stress, poor sleep — fix the inputs and the hormone recovers. The system is resilient.

After 40, you're dealing with two things happening simultaneously: that same downstream, training-stress-driven suppression layered on top of an actual age-related decline in baseline production. For most men, this decline begins in the late 30s and accelerates through the 40s and 50s. In women, the perimenopausal transition creates a parallel and often more abrupt shift in testosterone alongside the more widely discussed changes in estrogen and progesterone.

This is why "I'm just getting older" becomes such a convenient — and limiting — explanation for masters athletes. Some of what you're experiencing genuinely is the natural decline curve. But a meaningful portion of it is the same addressable, training-stress-driven suppression that affects athletes of any age — and it's being written off as inevitable aging rather than identified and treated.

That distinction is the entire point of this article.

Five Signs That Testosterone Is a Factor

Masters athletes have something younger athletes don't: decades of training history and a precise internal sense of what their effort-to-output ratio should feel like. When that ratio breaks down, you notice it earlier and more accurately than someone without that reference point. That's actually an advantage — if you use it.

Here's what declining testosterone looks like in practice for an athlete over 40.

1. Declining Performance That Doesn't Track With Training

You're putting in the same work — sometimes more — and results are moving in the wrong direction. Physiologically, testosterone is the primary signal driving muscular adaptation. It binds to androgen receptors and triggers the protein synthesis cascade that converts training stimulus into actual structural change. When that signal weakens, the adaptive response to identical training weakens proportionally. You're doing the work. The hormone that converts that work into results is underperforming.

2. Recovery That Keeps Getting Slower

This is usually the first thing masters athletes notice, and the thing they're most likely to misattribute purely to age. Staying sore longer. Sessions that used to take 24 hours to bounce back from now take 72. Some slowdown in recovery with age is expected and real. But a disproportionate decline — where recovery is getting worse faster than your training volume or intensity would explain — is often a testosterone signal, not simply a birthday.

The distinction matters because one is fixable and one isn't. Assuming it's all aging forecloses the conversation before it starts.

3. Body Composition Shifting in the Wrong Direction

Loss of lean muscle. Fat accumulating around the midsection. Strength that's increasingly difficult to maintain despite consistent training. After 40, this gets compounded by sarcopenia — the age-related loss of muscle mass that accelerates in the fifth decade — which makes it even more tempting to write off the whole picture as unavoidable.

But testosterone is a primary regulator of the muscle-to-fat ratio. Addressing testosterone specifically can meaningfully change this trajectory, even accounting for the real baseline shift that comes with aging. The question is never "is some of this age-related?" — some of it always is. The question is "how much of this is addressable?"

4. Flat Energy and Muted Motivation

For masters athletes, this one gets misread most often as burnout or as losing passion for the sport after years of training — a psychological explanation for what is frequently a neurochemical one. Testosterone influences dopamine signaling and drive directly. When it drops, the internal engine that previously powered training feels muted. Getting out the door feels harder. The competitive edge feels duller.

That's not you falling out of love with the sport. That's physiology — and physiology that can be evaluated and addressed.

5. Poor Resilience to Stress

This is the sign that matters most for masters athletes specifically, because it connects directly to the mechanism that underlies much of what this age group experiences.

The Cortisol-Testosterone Relationship: Why the Math Changes After 40

Here's the mechanism that explains more masters athlete fatigue than almost anything else in this area.

Cortisol and testosterone compete for the same upstream precursor hormones in the adrenal pathway. When cortisol is chronically elevated — from training load, work stress, poor sleep, or the accumulated life demands that tend to be substantially higher in your 40s and 50s than they were at 28 — it suppresses testosterone production directly. This is not a minor effect. It's a direct biochemical competition for shared precursors, and cortisol consistently wins.

Here's the aging-specific piece: your cortisol-testosterone ratio was more forgiving at 28 because baseline testosterone production was higher. The same cortisol elevation that you absorbed without meaningful consequence a decade ago now tips that ratio significantly further in the wrong direction. You have less hormonal buffer than you used to.

The exact same training load and the exact same life stress that had no measurable effect on your hormones in your 30s can meaningfully suppress testosterone in your 40s and 50s. That's not you becoming weaker or less resilient as a person. That's the math of the system changing — and it has specific, identifiable, addressable components.

How It Presents Differently: Men vs. Women After 40

In men, the decline is gradual but measurable across multiple domains: reduced strength and power, progressive loss of lean mass, lower libido, persistent fatigue, and mood changes — all of which get reflexively attributed to aging, when a meaningful portion is addressable physiology.

In women, the picture is more complex because testosterone is declining alongside estrogen and progesterone during the perimenopausal transition. The testosterone piece specifically tends to get completely overlooked because clinical conversations default almost entirely to estrogen. But testosterone decline in perimenopausal and postmenopausal women directly affects training tolerance, recovery capacity, power output, and motivation.

Critically: because female testosterone levels are naturally lower than male levels to begin with, even modest absolute declines produce noticeable functional effects. There is less margin before the deficit becomes symptomatic. This is a population that is being significantly underserved by the current standard of care, and it's an area where a performance-focused evaluation — rather than a general population hormone panel — makes a meaningful difference.

Why Standard Bloodwork Misses This

Standard testosterone testing in a general medical context typically measures total testosterone only. For masters athletes, that's frequently insufficient — and here's why.

Total testosterone tells you how much testosterone is circulating in the blood. It doesn't tell you how much is actually available to tissue. A significant portion of circulating testosterone is bound to sex hormone-binding globulin (SHBG), which increases with age and renders the bound testosterone biologically inactive. An athlete can have total testosterone that looks "normal" while their free testosterone — the biologically active fraction — is meaningfully low.

What to actually test: Total testosterone, free testosterone, and SHBG — evaluated together. For women going through the perimenopausal transition, testing alongside estrogen and progesterone provides a complete hormonal picture rather than a fragment of one.

The reference ranges used in standard panels are also calibrated for general population health, not athletic performance. A value at the low end of the normal range for a sedentary adult is not necessarily adequate for someone placing endurance training demands on their recovery system daily.

What to Do With This Information

Step one is confirmation. Symptoms alone aren't sufficient to act on, and this matters particularly for masters athletes because some overlap between testosterone symptoms and normal aging is expected. Testing gives you data rather than assumptions, and it allows you to distinguish how much of the picture is age-related baseline decline versus addressable suppression.

Step two is identifying the upstream drivers — because for a masters athlete, isolating what's addressable versus what's genuinely age-related is the entire point of the evaluation.

The modifiable drivers to assess:

• Chronic stress and cortisol elevation — the direct suppressor of testosterone through the shared precursor pathway described above
• Under-fueling and low energy availability — one of the most consistent drivers of hormonal disruption in endurance athletes at any age, and more impactful after 40 when hormonal buffer is reduced
• Sleep quality and quantity — the majority of testosterone production occurs during sleep, and both quality and quantity tend to decline in the fourth and fifth decades precisely when hormonal resilience is also declining
• Training load without adequate recovery — the same imbalance that drives cortisol elevation; matters more now than it did at 28
• Micronutrient status — particularly zinc (a direct cofactor in testosterone production) and vitamin D (which functions more like a hormone than a vitamin and has receptors in testosterone-producing cells)

The goal of this evaluation is not simply to raise a number. It's to identify what portion of the picture is genuinely addressable — fix that part directly and efficiently — and stop attributing fixable physiology to an aging narrative that forecloses intervention before it begins.

The Bottom Line for Masters Athletes

Declining performance despite solid training, slower recovery, body composition trending in the wrong direction, and motivation that's gone flat are not automatically explained by age. Some of it may be. A meaningful part of it, in most masters athletes, is not.

"You're just getting older" is doing too much work as an explanation when what's actually present is a combination of an addressable physiological pattern and a natural baseline shift — and distinguishing between the two requires evaluation, not assumption.

The next article in this series covers how to actually support testosterone naturally at this stage of training life — what the evidence shows moves the needle for masters athletes specifically, and how to approach it strategically.

Dr. Jason Barker is a naturopathic doctor with over 20 years of clinical experience working with endurance athletes. He is a two-time Ironman finisher and the founder of Natural Athlete Clinic. For individualized hormone testing and performance-focused protocols for masters athletes, visit naturalathleteclinic.com.