Hormonal responses to high- and moderate-intensity strength exercise

Area of Science:

• Exercise Physiology
• Endocrinology
• Sports Science

Background:

• Strength training elicits complex hormonal responses crucial for adaptation.
• Understanding acute and prolonged effects of varying intensities is vital for training optimization.

Purpose of the Study:

• To compare the acute and prolonged hormonal responses to moderate- versus high-intensity strength exercise in male athletes.
• To investigate the impact of exercise intensity on testosterone, cortisol, growth hormone, and other key hormones.

Main Methods:

• Nine male strength athletes completed moderate (70% 3/6-RM) and high-intensity (100% 3/6-RM) strength workouts.
• Blood samples were collected pre-exercise and at multiple time points up to 33 hours post-exercise.
• Analyzed hormones included testosterone, cortisol, LH, FSH, GH, IGF-1, and others.

Main Results:

• High-intensity exercise induced greater acute increases in testosterone and cortisol compared to moderate-intensity.
• Cortisol response correlated with increased adrenocorticotrophic hormone (ACTH).
• No significant differences in prolonged hormonal responses were observed between intensities; however, insulin-like growth factor 1 (IGF-1) levels were significantly lower the morning after exercise.

Conclusions:

• Exercise intensity differentially affects acute anabolic and catabolic hormone responses.
• Prolonged hormonal regulation appears less sensitive to acute exercise intensity differences within this timeframe.
• The overnight decrease in IGF-1 warrants further investigation into its physiological significance and underlying mechanisms.