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Growth hormone responses during intermittent weight lifting exercise in men
Summary
High load, low frequency weight lifting significantly elevates growth hormone (GH) levels post-exercise. Lower load, higher frequency exercise with equal work output did not elevate GH, suggesting load and frequency are key regulators.
Area of Science:
- Exercise Physiology
- Endocrinology
- Sports Science
Background:
- Intermittent weight lifting protocols vary in load and frequency.
- Understanding hormonal responses to different exercise parameters is crucial for training optimization.
Purpose of the Study:
- To investigate the impact of varying load and frequency in intermittent weight lifting on growth hormone (GH) secretion.
- To determine if total work output and duration are sufficient to elicit similar GH responses.
Main Methods:
- Five healthy males performed two 20-minute intermittent weight lifting protocols with identical work-rest intervals but different load/frequency.
- Exercise I: 7 sets of 7 reps at 85% Seven Repetition Maximum (SRM). Exercise II: 7 sets of 21 reps at 1/3 load.
- Blood samples analyzed for GH, lactate, and glucose during exercise and recovery.
Main Results:
- Exercise I elicited a significant increase in GH during recovery (peak at 5-15 min post-exercise).
- Exercise II showed no significant GH elevation.
- Significant correlation found between lactate and GH levels in Exercise I (r=0.99, P<0.01).
- No significant changes in plasma glucose were observed.
Conclusions:
- Exercise load and movement frequency are critical determinants of GH response in intermittent weight lifting.
- Equal total work output and duration do not guarantee similar hormonal outcomes.
- Higher intensity (load) exercise appears necessary to stimulate significant GH release.