Relationship between circulating cortisol and testosterone: influence of physical exercise.

Area of Science:

• Endocrinology
• Exercise Physiology
• Human Physiology

Background:

• Pharmacological administration of cortisol at rest reduces circulating testosterone.
• This has led to speculation that exercise-induced cortisol increases may lower testosterone.

Purpose of the Study:

• To investigate the relationship between circulating cortisol and testosterone (total and free) in men at rest and after intensive exercise.

Main Methods:

• Blood samples were collected from 45 men at rest and during exercise recovery over two trials.
• Radioimmunoassay was used to analyze cortisol, total testosterone, and free testosterone levels.
• Pearson correlation coefficients were calculated to assess relationships.

Main Results:

• At rest, no significant correlation was found between cortisol and total or free testosterone.
• Following exercise recovery, a significant negative correlation (r = -0.53) emerged between cortisol and total testosterone.
• A significant positive correlation (r = +0.21) was observed between cortisol and free testosterone post-exercise.

Conclusions:

• Intensive exercise facilitates a significant negative associative relationship between cortisol and total testosterone.
• A positive association between cortisol and free testosterone post-exercise may involve adrenal contributions or altered binding globulin dynamics.
• Observed relationships are associative, not causal, with small to moderate strength.