This week's "Study of the Week" is a review written by Brad Shoenfeld discussing post-exercise hypertrophic adaptations. It is a bit more science laden then I typically like to share or read myself, but I thought it was helpful in clarifying what the current literature demonstrates concerning this post-exercise period. Title
Post-exercise hypertrophic adaptations: A reexamination of the hormone hypothesis and its applicability to resistance training program design by Brad Schoenfeld, published ahead of print in Journal of Strength and Conditioning
Strength training leads to hypertrophic adaptations that are mediated by an array of signals. The signals appear to influence and be influenced by hormones and the endocrine system. Researchers have noted that strength training leads to distinctive and acute impact on various hormones such as insulin like growth factor and growth hormone. Researchers have also noted that specific types of strength training lead to greater hormone responses than other. Hypertrophy, or muscle building, strength training involving moderate intensities, short rest periods, and albeit higher volumes result in greater hormone responses when compared to lower volume, longer rest period, and higher intensity strength training. Correlation of higher levels of hormone response and greater muscle growth associated with this hypertrophy training leads researchers to propose that hormones are involved in producing greater muscular growth.
The review set out to assess the current literature concerning hormones roles in hypertrophy following strength training. The reviewer began by nothing that some research has shown that muscular hypertrophy occurs without post exercise hormone change. The question remained regarding whether hormone changes could increase hypertrophy. The reviewer continues by nothing a brief explanation of what hormones are affected by resistance training and that a number of these hormones have yet to be clarified by research as to their exact role.
The Reviewer notes that researchers who have attempted to assess the strength of correlation between hormone response post-exercise and muscular hypertrophy have resulted in conflicting results.
The Reviewer states that due to poorly defined experiments some of these studies may have failed to control for all variables resulting in poor quality of data and some studies displayed a selection bias.
The reviewer concludes his paper by saying that research currently is contradictory regarding whether or not post exercise hormone response plays an important role in increasing muscular hypertrophy.
I really enjoyed this study for two reasons. First it gave a wonderful summary of the hormones affected by resistance training as well as a summary of the current research relating hormones and exercise which lead me to other great studies. Second I think it shows that there is quite a bit about the mechanics of building muscle that is still unknown. This is powerful information because whenever you hear someone promising you the next great sure fire way to pack on muscle you will evaluate their proposal with a more critical mind because you understand that muscular hypertrophy is still not a fully understood process.
Practical, Purposeful, Information