Post-eccentric exercise blunted hGH response.

Area of Science:

• Exercise Physiology
• Endocrinology
• Sports Science

Background:

• Eccentric exercise is known to stimulate anabolic hormone release, crucial for muscle adaptation.
• The impact of preceding exercise types on subsequent hormonal responses requires further investigation.

Purpose of the Study:

• To determine if a prior acute concentric exercise bout attenuates the human growth hormone (hGH) response to a subsequent eccentric exercise bout.
• To compare physiological markers including hGH, creatine kinase (CK), and lactate between concentric and eccentric exercise protocols.

Main Methods:

• Nine healthy, untrained male university students participated in a controlled study.
• Participants completed both a concentric and an eccentric exercise bout on separate occasions, one week apart.
• Serum hGH, CK, and lactate levels were measured pre-exercise and at multiple time points up to 32 hours post-exercise.

Main Results:

• Lactate levels were significantly higher immediately after concentric exercise compared to eccentric exercise.
• While both exercise types elevated hGH, the response reached statistical significance only after the concentric bout.
• Peak serum creatine kinase (CK) effect size was greater following concentric exercise (1.3) than eccentric exercise (0.9).

Conclusions:

• A preceding concentric exercise bout may blunt the expected anabolic human growth hormone (hGH) response after eccentric exercise.
• This suggests a potential interference effect of exercise modality order on hormonal adaptations.
• Findings have implications for optimizing exercise sequencing to maximize training-induced anabolic responses.