Exercise-Induced hormone elevations are related to muscle growth

Gerald T. Mangine, Jay R. Hoffman, Adam M. Gonzalez, Jeremy R. Townsend, Adam J. Wells, Adam R. Jajtner, Kyle S. Beyer, Carleigh H. Boone, Ran Wang, Amelia A. Miramonti, Michael B. Lamonica, David H. Fukuda, E. Lea Witta, Nicholas A. Ratamess, Jeffrey R. Stout

Research output: Contribution to journalArticlepeer-review

35 Scopus citations

Abstract

Partial least squares regression structural equation modeling (PLS-SEM) was used to examine relationships between the endocrine response to resistance exercise and muscle hypertrophy in resistance-Trained men. Pretesting (PRE) measures of muscle size (thickness and cross-sectional area) of the vastus lateralis and rectus femoris were collected in 26 resistance-Trained men. Participants were randomly selected to complete a high-volume (VOL, n = 13, 10-12RM, 1-minute rest) or high-intensity (INT, n = 13, 3-5RM, 3-minute rest) resistance training program. Blood samples were collected at baseline, immediately postexercise, 30-minute, and 60-minute postexercise during weeks 1 (week 1) and 8 (week 8) of training. The hormonal responses (testosterone, growth hormone [22 kD], insulin-like growth factor-1, cortisol, and insulin) to each training session were evaluated using area-under-The-curve (AUC) analyses. Relationships between muscle size (PRE), AUC values (week 1 + week 8) for each hormone, and muscle size (POST) were assessed using a consistent PLS-SEM algorithm and tested for statistical significance (p < 0.05) using a 1,000 samples consistent bootstrapping analysis. Group-wise comparisons for each relationship were assessed through independent t-Tests. The model explained 73.4% (p < 0.001) of variance in muscle size at POST. Significant pathways between testosterone and muscle size at PRE (p = 0.043) and muscle size at POST (p = 0.032) were observed. The ability to explain muscle size at POST improved when the model was analyzed by group (INT: R2 = 0.882; VOL: R2 = 0.987; p< 0.001). No group differences in modal quality were found. Exercise-induced testosterone elevations, independent of the training programs used in this study, seem to be related to muscle growth.

Original languageEnglish
Pages (from-to)45-53
Number of pages9
JournalJournal of Strength and Conditioning Research
Volume31
Issue number1
DOIs
StatePublished - 2017
Externally publishedYes

Keywords

  • Endocrine response
  • Hypertrophy
  • Partial least squares regression
  • Structural equation modeling

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