title: Exercise-Induced Hormone Elevations Are Related to Muscle Growth.
abstract: Mangine, GT, Hoffman, JR, Gonzalez, AM, Townsend, JR, Wells, AJ, Jajtner, AR, Beyer, KS, Boone, CH, Wang, R, Miramonti, AA, LaMonica, MB, Fukuda, DH, Witta, EL, Ratamess, NA, and Stout, JR. Exercise-induced hormone elevations are related to muscle growth. J Strength Cond Res 31(1): 45-53, 2017-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: R = 0.882; VOL: R = 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.
authors.affiliation: 1Department of Exercise Science and Sport Management, Kennesaw State University, Kennesaw, Georgia; 2Department of Educational and Human Sciences, Institute of Exercise Physiology and Wellness, University of Central Florida, Orlando, Florida; and 3Health and Exercise Science, The College of New Jersey, Ewing, New Jersey.
authors.forename: Gerald T
authors.initials: GT
authors.lastname: Mangine
authors.forename: Jay R
authors.initials: JR
authors.lastname: Hoffman
authors.forename: Adam M
authors.initials: AM
authors.lastname: Gonzalez
authors.forename: Jeremy R
authors.initials: JR
authors.lastname: Townsend
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Wells
authors.forename: Adam R
authors.initials: AR
authors.lastname: Jajtner
authors.forename: Kyle S
authors.initials: KS
authors.lastname: Beyer
authors.forename: Carleigh H
authors.initials: CH
authors.lastname: Boone
authors.forename: Ran
authors.initials: R
authors.lastname: Wang
authors.forename: Amelia A
authors.initials: AA
authors.lastname: Miramonti
authors.forename: Michael B
authors.initials: MB
authors.lastname: LaMonica
authors.forename: David H
authors.initials: DH
authors.lastname: Fukuda
authors.forename: E Lea
authors.initials: EL
authors.lastname: Witta
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Ratamess
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Stout
mesh_terms: D000328:Adult; D056352:Athletes; D019382:Human Growth Hormone / Q000097:blood; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000096:biosynthesis; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply / Q000502:physiology*; D052097:Quadriceps Muscle / Q000502:physiology; D055070:Resistance Training / Q000379:methods*; D012146:Rest / Q000502:physiology; D013739:Testosterone / Q000097:blood; D055815:Young Adult
chemical_list: D019382:Human Growth Hormone; D013739:Testosterone; D007334:Insulin-Like Growth Factor I; D006854:Hydrocortisone