Every day, more and more people are being affected by stress. The American Psychological Association states that 76% of Americans have had negative health outcomes as a result of stress or anxiety.  While stress is often seen as a part of life, it is important to understand its potential impact on our body, specifically on testosterone levels.
The short answer: Chronic stress lowers testosterone, not simply due to cortisol, although it is a factor. But, rather due to other issues caused by the condition, such as disrupted sleep. However, acute stress, such as strenuous exercise activity only seems to deplete total testosterone for a few hours after the activity itself, with levels returning to no observable difference at rest. And even during this time free testosterone levels were slightly elevated due to other, not fully understood, mechanisms within the body.
Stress and anxiety can have wide-ranging effects on our physical, mental, and emotional health. When it comes to testosterone, excess stress can disrupt the normal functioning of the male reproductive system. Cortisol, a hormone produced by the adrenal glands in response to stress, can adversely affect testosterone production. While acute stress, such as the adrenaline rush experienced during a dangerous situation, may temporarily increase testosterone levels, chronic stress has the opposite effect.
Some of the specific effects of stress on the male reproductive system include:
Excessive stress and anxiety can lead to a decrease in libido or a lack of interest in sex. This can be attributed to the disruption of testosterone production caused by the elevated levels of cortisol. When cortisol levels are high, it can interfere with the normal biochemical processes involved in sexual desire and function. 
Stress can also impact sperm production and maturation. The excessive release of cortisol can interfere with the production and maturation of sperm cells, leading to a decrease in sperm count and quality. This can ultimately affect fertility and reproductive health. 
Chronic stress poses a significant threat to testosterone health, with mounting evidence suggesting a direct correlation between stress and low testosterone levels. On top of that the male reproductive system, including the testes, prostate, and urethra, can be vulnerable to infections if stress compromises the immune system. 
One line of research has focused on the effects of cortisol administration on testosterone levels. Human studies have demonstrated that the administration of cortisol into the circulation at rest leads to reduced blood testosterone levels.
These findings have led researchers to speculate that physical exercise-induced cortisol increases may also result in subsequent reductions in circulating testosterone levels. However, it is important to note that these findings are correlational and do not establish a causal relationship between cortisol and testosterone.
A study by Bambino and Hsueh (1981) explored the effect of high doses of glucocorticoids, including cortisol, on testicular Leydig cell function in rats. 
The researchers found that the production of testosterone decreased as a result of glucocorticoid administration. Similarly, Cumming et al. (1983) conducted a study on humans using pharmacological doses of cortisol to induce a decrease in testosterone production.  They speculated that cortisol disrupted the testicular testosterone production process by disrupting the hormone's biosynthesis pathway.
While these studies provide evidence of a negative relationship between cortisol and testosterone, it is important to recognize that the cortisol doses used in these experiments were pharmacological and may not reflect physiological levels seen in everyday life.
Furthermore, the observed relationship is associative rather than causative, and the exact physiological mechanisms underlying this relationship remain unclear.
Exercise is a known stressor that can cause an increase in cortisol secretion. The release of cortisol during exercise helps maintain blood glucose levels and mobilize energy stores. At the same time, testosterone levels tend to increase in response to exercise, particularly when the intensity threshold is reached (Wilkerson et al., 1980). 
Given the opposing effects of cortisol and testosterone, it is not surprising that researchers have hypothesized a potential relationship between these hormones during and after exercise. Several studies have explored this hypothesis, with varying results.
In a study by Hoogeveen and Zonderland (1996), a negative relationship between cortisol and testosterone  was observed in response to a cycling exercise. Meaning that testosterone was lowered after the exercise activity was completed. Similarly, Nindl et al. (2001) reported a negative association between these hormones in military personnel undergoing intense training.  However, these studies had small sample sizes and did not statistically analyze the relationship.
To address these limitations, Kaye K. Brownlee et al. (2021) conducted a study with 45 physically active men to examine the relationship between cortisol and testosterone at rest and during exercise recovery.  The researchers collected blood samples at rest and 1 hour into recovery from intensive exercise. They found a significant negative raise in cortisol and drop in total testosterone during exercise recovery, but no significant association at rest.
These findings suggest that exercise allows for the development of a negative relationship between cortisol and testosterone. However, it is important to note that this relationship is associative and not causal in nature. Further research is needed to fully understand the mechanisms underlying this relationship and its implications for exercise-induced changes in testosterone levels.
One of the primary ways in which stress affects testosterone levels is through sleep disruption. Chronic stress often leads to sleep disturbances, such as insomnia or insufficient sleep duration. Research has shown that sleep loss caused by stress can decrease total testosterone levels by as much as 15%. Therefore, addressing sleep-related issues is crucial for maintaining optimal testosterone health. 
Another significant aspect of the stress-testosterone relationship is the impact of stress on blood sugar levels. When faced with stress, our bodies release glucose into the bloodstream to provide energy for the fight-or-flight response. However, prolonged exposure to high blood sugar levels, caused by chronic stress, can lead to insulin resistance and an increased risk of type 2 diabetes. Notably, higher blood sugar and diabetes risk are directly correlated with lower testosterone levels. 
The connection between stress and obesity is well-documented, with chronic stress being a significant contributing factor to weight gain. Stress triggers cravings for high-calorie, comfort foods, leading to overeating and a sedentary lifestyle. As expected, obesity has been associated with higher rates of low testosterone in men.
The specific physiological mechanisms underlying the cortisol-testosterone relationship are not fully understood. However, several postulates have been proposed by researchers.
Cumming et al. (1983) suggested that cortisol may disrupt the testicular steroidogenic process, leading to a decrease in testosterone production. They found that cortisol administration resulted in decreased testosterone levels without affecting luteinizing hormone (LH) or prolactin, indicating a direct effect on testicular function. 
Animal studies have provided further support for this hypothesis. Bambino and Hsueh (1981) discovered that glucocorticoids inhibited LH receptor activity in rat testes, suggesting an interference with the binding of LH and subsequent steroidogenesis. 
It is important to note that cortisol and testosterone are both derived from the same precursor and share a structural similarity. This similarity may contribute to their competition for binding sites on carrier proteins, leading to changes in the amount able to circulate. Additionally, exercise-induced changes in pH and temperature may affect binding protein affinity, further influencing the levels of free testosterone (Rosner, 1990; Obminiski and Stupnicki, 1996). 
To complicate matters further, the relationship between cortisol and free testosterone appears to be different from that of total testosterone. Kaye K. Brownlee et al. (2021) found a positive relationship between cortisol and free testosterone during exercise recovery. 
This unexpected finding could be attributed to increased adrenal contribution of testosterone or alterations in binding protein affinity.
Ultimately that depends on the type of stress, it seems that short term cortisol increases from strenuous activity are counter acted by other factors that result in free testosterone staying high even if overall testosterone levels are reduced. However, chronic stress can have a significant impact on testosterone levels. This is partially due to chronic stress impact on sleep and eating habits which in turn effect testsosterone.
By understanding the effects of stress on the male reproductive system, recognizing signs of low testosterone, and implementing effective stress management strategies, you can take control of your health and regain balance in your life.
Remember, if you are experiencing persistent symptoms or concerns, consult with a healthcare professional who can provide personalized guidance and support.