Yes, overtraining can lower testosterone, sometimes significantly. Men who chronically overtrain, especially in endurance sports, can see resting testosterone levels drop to 50–75% of what’s normal for their age. The effect isn’t just a temporary dip after a hard workout. In some athletes, testosterone stays suppressed for as long as the excessive training continues.
How Overtraining Suppresses Testosterone
Your brain controls testosterone production through a hormonal chain reaction. The hypothalamus releases a signaling hormone (GnRH) in pulses, which tells the pituitary gland to release LH, which tells the testes to produce testosterone. Overtraining disrupts this chain at the top. The hypothalamus reduces or blunts its signaling, and the pituitary becomes less responsive even when stimulated directly.
In one study tracking men through 60 weeks of exercise, both moderate and high-intensity groups showed lower free testosterone, lower LH, and higher levels of a protein that binds testosterone and makes it unavailable. When researchers injected the signaling hormone directly to test pituitary function, both groups had a blunted response, meaning the gland itself had become less reactive. The high-intensity group showed more pronounced changes across the board.
This pattern, called secondary hypogonadism, means the testes are capable of producing testosterone but aren’t receiving the signal to do so. It’s the same mechanism that causes menstrual disruption in overtrained female athletes.
The Role of Undereating
Overtraining rarely happens in isolation. Most athletes who push training volume to extremes also fall into a caloric deficit, sometimes without realizing it. This combination of high energy expenditure and insufficient food intake is now recognized as Relative Energy Deficiency in Sport (RED-S), and it amplifies the hormonal damage considerably.
In one clinical case, a male athlete with overtraining syndrome and chronic undereating had LH levels of just 0.5 mIU/mL, well below the normal range of 1.7 to 8.6. His testosterone was extremely low as a direct result of his brain shutting down reproductive signaling to conserve energy. The condition reversed with adequate food intake and rest. This is a key point: the energy deficit itself suppresses the hormonal signal, independent of exercise stress. Two athletes doing the same training volume can have very different testosterone outcomes depending on whether they’re eating enough to match their expenditure.
Endurance Athletes Are Most Affected
Not all types of training carry the same risk. The condition most commonly appears in men doing prolonged endurance activities: distance running, cycling, race walking, and triathlon training. Researchers have given it a specific name, the “exercise-hypogonadal male condition,” to distinguish it from other causes of low testosterone.
Roughly 15–25% of men doing chronic endurance training develop this profile. Their resting testosterone sits at the very low end of the clinically normal range, and in some cases dips into what would technically qualify as testosterone deficiency. These aren’t temporary post-workout drops. The suppression persists at rest and doesn’t appear to be a transient phenomenon tied to recent training sessions.
High-volume resistance training can also contribute, particularly when combined with caloric restriction or inadequate recovery. But the research consistently points to endurance training as the primary driver.
Symptoms Beyond Fatigue
The tricky part of overtraining-induced low testosterone is that many symptoms overlap with ordinary tiredness. Fatigue, poor sleep, irritability, and loss of motivation are common in anyone who’s training hard. But when testosterone drops far enough, additional signs emerge that point to something more than just needing a rest day.
These include reduced libido, erectile dysfunction, difficulty concentrating, depressed mood, loss of muscle mass despite continued training, increased body fat (particularly around the abdomen), and reduced bone density over time. Insomnia, anxiety, restlessness, and waking up feeling unrefreshed are also characteristic of overtraining syndrome specifically. The combination of persistent performance decline with mood and sexual symptoms is what separates overtraining from normal hard training.
How Testosterone Is Measured
If you suspect overtraining has affected your hormones, a blood test for total and free testosterone is the starting point. However, diagnosing overtraining through hormone levels alone is unreliable. A systematic review of hormonal markers in overtrained athletes found that resting hormone levels, including testosterone, were mostly normal when looked at individually. No single hormone test was altered in more than half the studies reviewed.
The one marker that showed the most consistent change was the ratio of testosterone to cortisol (the body’s primary stress hormone). A decline of 30% or more from a person’s own baseline has historically been proposed as an indicator of insufficient recovery. But even this has limits: a 30% drop in the ratio doesn’t always correspond to a measurable decline in performance, and the ratio varies widely between individuals. It’s most useful when you have your own previous bloodwork to compare against, not as a standalone diagnostic tool.
Recovery Timeline
The good news is that overtraining-induced testosterone suppression is reversible. Because the problem originates in the brain’s signaling rather than damage to the testes, recovery is possible once the underlying stress is removed. That means reducing training volume, increasing caloric intake (especially if you’ve been in a deficit), and prioritizing sleep.
There’s limited data on exact timelines specific to overtraining recovery, but research on other forms of secondary hypogonadism suggests that gonadotropin levels (LH and FSH) typically recover within 3 to 6 months once the suppressive stimulus is removed, with testosterone following a similar trajectory. Athletes with milder suppression may bounce back faster. Those who have been chronically overtrained and underfed for years may take longer, and full recovery depends on actually addressing the energy deficit rather than simply reducing mileage while continuing to undereat.
For most men, returning to a sustainable training load with proper nutrition is enough. The clinical case reports in the literature consistently show hormone normalization without any pharmaceutical intervention, as long as the athlete actually commits to recovery rather than cutting volume by 10% and hoping for the best.