Hormonal and growth factor responses to heavy resistance exercise protocols

Area of Science:

• Exercise Physiology
• Endocrinology
• Sports Science

Background:

• Understanding the hormonal responses to resistance training is crucial for optimizing exercise protocols.
• Heavy resistance exercise protocols (HREPs) involve manipulating load, rest periods, and total work.
• Endogenous anabolic hormones and growth factors play a key role in muscle adaptation and repair.

Purpose of the Study:

• To investigate the effects of different heavy resistance exercise protocols on anabolic hormone and growth factor release.
• To compare the temporal and integrated responses of serum human growth hormone (hGH), testosterone (T), and somatomedin-C (SM-C) to various HREPs.

Main Methods:

• Nine male subjects participated in six randomized HREPs, varying in load (5 vs. 10 RM), rest (1 vs. 3 min), and total work.
• Serum concentrations of hGH, testosterone (T), somatomedin-C (SM-C), glucose, and whole blood lactate (HLa) were measured pre-, mid-, and post-exercise.
• Measurements were taken at multiple time points up to 120 minutes post-exercise to capture hormonal dynamics.

Main Results:

• All HREPs induced significant temporal increases in testosterone (T), but integrated responses (AUC) did not differ.
• The H10/1 protocol (high work, 1 min rest, 10 RM) elicited the highest temporal and integrated hGH responses.
• Somatomedin-C (SM-C) responses varied and did not consistently correlate with hGH changes; no integrated differences were found.

Conclusions:

• Hormonal and growth factor release patterns are complex and depend on specific HREP characteristics and physiological mechanisms.
• Different HREPs may differentially impact muscle and connective tissue growth due to variations in hormonal release.
• The H10/1 protocol appears most effective for stimulating hGH release among the tested HREPs.