Repeated Bouts of Exercise Period without Sufficient Rest Blunts GH Responses

A few years ago a book called the Bulgarian Burst System was printed which was supposed to give the training secretes of the Bulgarians weightlifters.  It went on to explain how the Bulgarian weightlifters trained 6 times a day with short, high intensity sessions that lead to explosive increases in muscle growth and strength.  It made sense that short high intensity sessions several times a day would increase GH and lead to higher increases in anabolic hormones, but according to the newest research this is just not the case.  In this month’s journal of Medicine & Science in Sports & Exercise, researchers reported that GH responses were suppressed in response to high intensity exercise with a recovery period less than 3 hours.  In this interesting study, research subjects were divided into three groups: 1.) resistance exercise only 2.) an all out bicycle sprint session followed by a 60-minute rest period followed by resistance exercise 3.) An all out sprint session followed by a 3 hour-rest period followed by resistance exercise.   You may be wondering why the researchers had the subjects perform a all-out exhaustive sprint session before the resistance training session.  An all out sprint session produces large increases in GH, the researchers wanted to see is the high intensity resistance exercise program also would produce large increases in GH with a different recovery times (60 minute rest and 3 hour rest periods).  Results of the study concluded that after each intense sprint sessions there were large increases in GH, however performing a resistance training session after a 3 hour rest period only resulted in a small GH response, furthermore performing a resistance training session with less than a hour rest period resulted in a blunted GH response to resistance exercise.   So much for the Bulgarians training six times a day with high anabolic hormone responses…seems like a recipe for overtraining!  Although the actual role of GH in muscle growth remains unclear, combinations of high GH and local growth factors produced in muscle (MGF, IGF-1) would activate anabolic processes in muscle.  Therefore, a blunted GH response to exercise might have an undesirable effect if one is trying to produce maximal increases in muscle mass.  Based on the research, if you are going to train with multiple training sessions make it early morning and later in the afternoon with sufficient rest periods. 

It’s Not Growth Hormone but Growth Hormones!

    We commonly think of GH as a single hormone, but it is well recognized now that there are over 100 molecular isoforms of GH that exist in human circulation11,16. GH should no longer be regarded as a single hormone, but rather a “family of related GH peptides.” Exercise is one of the most potent physiological stimulators of pulsatile GH secretion and thus increases the concentration of IGF-I. Factors such as the training status, age, exercise duration, and peak intensity of the exercise bout and the total workload performed will influence not only the average GH secretion but also the pulsatile pattern of GH secretion, which is equally important for the GH-regulated secretion of IGF-I. Future research is currently underway to determine the exact role of the different GH isoforms and their effect on muscle hypertrophy and performance.

    In conclusion, contrary to the media printing articles reporting GH is not important for building muscle, it is!!  GH works synergistically with other hormones (testosterone and IGF-1) to increase protein synthesis and muscle mass.  GH has direct anabolic action on muscle that occurs independently of IGF-1 and is essential for building muscle.

 

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