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Nocturnal hormonal responses to resistance exercise
R G McMurray1, T K Eubank, A C Hackney
1Applied Physiology Laboratory, University of North Carolina, Chapel Hill 27599-8700, USA.
Summary
Resistance exercise minimally impacts nocturnal human growth hormone and cortisol. However, it may influence testosterone and thyroid hormone levels, potentially aiding muscle growth.
Area of Science:
- Endocrinology
- Exercise Physiology
- Sports Science
Background:
- Nocturnal hormone secretion is crucial for physiological recovery and adaptation.
- Understanding the impact of late-evening exercise on these hormones is important for athletes.
Purpose of the Study:
- To investigate the effects of heavy resistance exercise on nocturnal endocrine responses.
- To analyze changes in cortisol, testosterone, human growth hormone, and thyroid hormones post-exercise.
Main Methods:
- Eight trained weightlifters participated in a controlled study with both exercise and no-exercise trials.
- Blood samples were collected at regular intervals throughout the night following evening exercise.
- Hormone levels (cortisol, testosterone, hGH, T3, T4) were measured.
Main Results:
- Human growth hormone and cortisol showed transient increases post-exercise but normalized within an hour.
- Nocturnal levels of human growth hormone and cortisol were not significantly affected by resistance exercise.
- Testosterone showed a potentially greater nocturnal rise after exercise, while T4 levels were lower nocturnally post-exercise.
Conclusions:
- Resistance exercise appears to have limited impact on nocturnal human growth hormone and cortisol.
- Nocturnal testosterone and T4 alterations following resistance exercise may play a role in muscle anabolism.