Does Military Fitness Training Reduce Testosterone?

Written by Ben Bunting: BA(Hons), PGCert. Sport & Exercise Nutrition. British Army Physical Training Instructor.  


When it comes to the question of whether or not military fitness training reduces testosterone, it's important to look at the evidence.

For example, there's a correlation between the amount of total and trunk fat mass a person has at the onset of a training program, and how the regime of training affects testosterone levels over time.

In addition, there's a link between the quality of the diet a person consumes and how much fat they build.

Moreover, there's a link between sleep deprivation and lowered testosterone levels. Therefore, you'll want to ensure you get enough rest in order to maintain a healthy physique.

However, with my pesonal experiences of basic training I saw a common theme that may have a negative impact on hormones:

  • Lack of quality sleep
  • High levels of stress
  • Lots of carbohydrate rich foods
  • Fast paced activities including physical training
  • Relentless changes to the schedule
  • Sleeping outside, on the floor with little shelter 
  • Long patrols carrying large weights

Stress causes testosterone levels to drop

Low testosterone is associated with depression, mood swings and sexual dysfunction.

There are many factors to consider, and it may be necessary to seek medical help. In the past two decades, testosterone levels have decreased significantly in men.

Testosterone plays an important role in the development of muscle mass, brain function, and emotional stability.

The hormone also regulates social behavior and sexual performance.

Research on the connection between stress and low testosterone is still in its infancy.

While some studies have shown that lower testosterone is associated with physical stress, others have found no link between stress and low testosterone.

However, there are some factors that can affect testosterone levels, including weight, estrogen, and a lack of sleep.

It has been shown that cortisol, a stress hormone, can affect testosterone levels. Chronically elevated cortisol can inhibit the production of testosterone.

This suppresses the reproductive system and immune system. Additionally, cortisol can increase glucose in the bloodstream, which triggers the fight-or-flight mechanism.

Testosterone levels can increase or decrease during acute or chronic stress.

Previously, it has been reported that lower testosterone levels are associated with anticipatory, psychological, and physical stress.

Studies of the relationship between testosterone and stress have been limited to male subjects.

A study of 600 elderly Dutch men showed that men with low testosterone were more likely to have symptoms of depression.

Researchers believe that the difference in gender may contribute to the differences in the biological responses to stress.

Women produce testosterone following different metabolic pathways than men.

The Relationship Between Testosterone and Anxiety

Military training and military fitness tests can cause anxiety amongst recruits and trained personnel alike.

Anxiety is a condition of feeling uneasy. This feeling is often experienced after experiencing stress.

Several factors may contribute to the development of anxiety. These include low testosterone levels.

Testosterone is known to have anxiolytic properties. It affects the brain, by activating GABAA receptors.

However, testosterone can have variable effects. Some studies suggest that testosterone may increase synaptic plasticity.

It is thought that estrogen plays a role in the anxiolytic effect of testosterone. Estradiol is a metabolite of testosterone.

Research has shown a correlation between lower testosterone levels and an increase in anxiety.

In addition, women with anxiety disorders have lower testosterone levels. Those with lower testosterone levels are also more likely to have behavioural problems.

A landmark study involved 700 men and women. It measured the testosterone/cortisol ratio in response to acute stress and in response to perceived performance.

The results showed a dose dependent effect of testosterone on anxiety.

Various studies have also been carried out to determine the effect of testosterone on depression.

Results of the studies indicate that testosterone has an anti-depressant effect in hypogonadism.

Interestingly, the link between anxiety and low testosterone in younger men was found. Researchers also found that there was a correlation between low testosterone levels and mood swings.

Research on the relationship between testosterone and anxiety has not only demonstrated a correlation, but it has also revealed a causal link.

Although there have been multiple studies on this topic, there is still much to be learned. 

Sleep deprivation lowers testosterone levels

The effects of sleep deprivation on testosterone levels during military fitness training were examined in an experimental study.

Testosterone is important for male sexual behavior, physical performance, and reproduction. A low testosterone level can lead to decreased energy, increased fatigue, and poor concentration.

A group of young men was studied in an Officer Candidate School. Their testosterone levels were suppressed for one week.

This study was conducted in Khyber Pakhtunkhwa, Pakistan.

In a previous study, 50 Special Forces soldiers deployed from a temperate climate to a tropical environment.

They were slept for five hours a night. Participants woke up and were tested for serum cortisol and testosterone.

The results showed that participants had lower testosterone levels than the control group.

This was because of the nonquantitative threshold effect. However, there was no correlation between testosterone level and increased cortisol levels found in the study.

Insomnia and testosterone

A decline in testosterone can affect both the quality of sleep and performance. As we age, the levels of testosterone in men decrease by about 1 to 2 percent a year.

Men with low testosterone have a harder time entering the REM stage of sleep and are more likely to suffer from erectile dysfunction.

While low testosterone can affect men's sleep and physical health, it is not clear how long a deficiency lasts.

Some studies show that even a single night of total sleep deprivation can reduce testosterone by 10 to 15 percent.

Further research is needed to determine the effects of sleep on testosterone, particularly with regard to the impact on physical performance.

Diet during training may affect testosterone

A recent study by nutritionists featuring in the Nutrition and Health journal examined the effects of a high carbohydrate diet on testosterone levels in healthy adult males. 

Testosterone is also involved in red blood cell production. Men can lose muscle and gain fat when testosterone levels decline.

It is crucial to maintain proper carbohydrate and protein intake to keep levels above borderline. Having a balanced diet is the best way to enhance performance.

Carbohydrates are sugar molecules that the body converts into energy. Some of the best forms of carbohydrates are pressed fruit juices, white rice, and ground vegetables. If you exercise regularly, you should eat enough carbs.

Protein is also critical for maintaining muscle. Proteins are made up of amino acids. When the body breaks down proteins too quickly, it produces toxic ammonia and other byproducts.

A study examined the long-term effects of a high protein, low carbohydrate diet on men's testosterone levels.

Compared to the high carbohydrate diet, the low protein, high carbohydrate diet resulted in significantly lower testosterone levels.

Low-carbohydrate diets may also affect testosterone levels by causing a decrease in free testosterone. They are also associated with a rise in cortisol. However, more research is needed to determine if this is the case.

Furthermore, calorie intake can also be a factor to consider during training. For example, the energy deficit was associated with a 50 to 65 percent testosterone depletion during US Army Ranger School.

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Excessive exercise associated with attenuated testosterone decrements

Excessive exercise can lead to low testosterone in men. Overtrained athletes have higher levels of cortisol, which breaks down fat and muscle.

Men who participate in high-volume endurance exercises, such as running, have lower levels of testosterone.


Overtraining can cause a number of problems including fatigue, decreased heart rate, lower testosterone and increased cortisol levels. These changes can negatively impact an athlete's performance. 

When a man's testosterone levels decrease, the body cannot repair itself as well. A man's bones may become weaker and may develop stress fractures. This can put him at a higher risk of developing osteoporosis.

Endurance Training and Testosterone

Many studies suggest that endurance training can negatively impact the male reproductive system.

It is also known that prolonged exercise can disrupt the hormonal production and clearance of hormones, such as testosterone.

Testosterone is a male hormone that ensures a man's health and performance. It affects body composition, strength, and virility. In addition, it is important in helping muscles to heal and repair DNA.

Low levels can result in a number of health problems, including fatigue, loss of muscle mass, and belly fat.

In the 1970s, Dr. John Sutton began a series of studies on human exercise and the effects it has on the male reproductive system.

He showed that standardized short-term submaximal and maximal endurance exercises altered testosterone responses.

Eventually, researchers identified a condition called Exercise-Hypogonadal Male Condition (EHMC). Approximately 15% of male endurance athletes are diagnosed with EHMC, which may be a result of HPG axis dysfunction.

EHMC has been studied in male wrestlers, long-course triathletes, and Olympic distance race walkers. It has been linked to a number of factors, including a decrease in testosterone and the production of Leydig cells.

The study suggests that testosterone and other reproductive hormones are significantly impacted by endurance training.

Among men, testosterone is lowest in endurance athletes, followed by strength athletes. Endurance training also increases endothelial proteins in the spinal cord.

Nevertheless, there is not enough evidence to say that all exercise causes the decline in testosterone levels.

In fact, there are some forms of exercise that increase total testosterone, particularly HIIT training. 

Maintaining a healthy balance

Military fitness training can have negative effects on hormone health if not properly maintained.

Hormone imbalances, especially testosterone, can cause weight loss, fatigue, and other negative symptoms.

In order to prevent these problems, body composition and dietary strategies should be implemented before and during military fitness training.

Military Field Exercises and Testosterone

One of the most important aspects of military field exercises is the effects that they have on the body. The hormonal effects of training under stress may have long term implications.

The calorie deficit produced by such exercises may be associated with a drop in testosterone.

This could result in decreased physical performance, fatigue, and an increased risk of injury. Therefore, a long recovery period is essential to prevent such negative effects.

A study examined testosterone and cortisol after an eight-day exercise. It was found that morning cortisol concentrations were lower after the exercise.

The effects of this exercise were more pronounced in men than in women.

There is an ongoing Defense Department study. Researchers will test whether a single dose of testosterone undecanoate can safely and effectively attenuate total muscle mass loss and improve military-relevant measures of physical performance.

The Optimizing Performance in Soldiers (OPS) study is underway at Louisiana State University in Baton Rouge, Louisiana.

This randomized, placebo-controlled, double-blind trial will evaluate the effectiveness of a weekly dose of testosterone, provided to 50 young men ages 18 to 39.

Participants will live in a research facility and undergo rigorous physical activity. Their food and weight will be monitored. 


The Department of Defense is investigating whether military fitness training can boost testosterone levels during combat. In particular, the testosterone/cortisol ratio is being studied.

This ratio indicates the relative anabolic and catabolic balance of testosterone and cortisol. When the two are balanced, the body is more productive.

Studies have shown that prolonged physical activity, sleep deprivation, and extreme stress can reduce testosterone.

Therefore, maintaining normal testosterone is important. It can help prevent injury, and improve performance. Likewise, low testosterone levels can cause debilitating symptoms.

Researchers are now studying how testosterone levels change during calorie restriction.

Testosterone undecanoate is being tested in a prospective, randomized, placebo-controlled, double-blind study to determine if it can safely enhance performance during SUSOPS.

The Optimizing Performance in Soldiers Study (OPS II) will examine a single dose of testosterone undecanoate to determine whether it can safely enhance performance during SUSOPS.

The study will enroll 50 young men ages 18-39. Participants will undergo rigorous physical activity and will receive weekly testosterone shots. They will also live in a research facility where they will be monitored on an outpatient basis.

The recovery process after demanding military field exercises has received little attention in the literature.

However, knowledge of the recovery process is important for long-term development of soldiers' physical performance.


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