Acute resistance exercise stimulates sex-specific dimeric immunoreactive growth hormone responses.
OBJECTIVE
We sought to determine if an acute heavy resistance exercise test (AHRET) would elicit sex-specific responses in circulating growth hormone (GH), with untreated serum and serum treated with a reducing agent to break disulfide-bindings between GH dimers.


METHODS
19 untrained participants (nine men and ten women) participated in an acute heavy resistance exercise test using the back squat. Blood samples were drawn before exercise (Pre), immediate post (IP), +15 min (+15), and +30 min (+30) afterwards. Serum samples were chemically reduced using glutathione (GSH). ELISAs were then used to compare immunoreactive GH concentrations in reduced (+GSH) and non-reduced (-GSH) samples. Data were analyzed using a three-way (2 sex × 2 treatment × 4 time) mixed methods ANOVA, with significance set at p ≤ 0.05.


RESULTS
GSH reduction resulted in increased immunoreactive GH concentrations when compared to non-reduced samples at Pre (1.68 ± 0.33 μg/L vs 1.25 ± 0.25 μg/L), IP (7.69 ± 1.08 μg/L vs 5.76 ± 0.80 μg/L), +15 min (4.39 ± 0.58 μg/L vs 3.24 ± 0.43 μg/L), and +30 min (2.35 ± 0.49 μg/L vs 1.45 ± 0.23 μg/L). Also, women demonstrated greater GH responses compared to men, and this was not affected by reduction.


CONCLUSIONS
Heavy resistance exercise increases immunoreactive GH dimer concentrations in men and women, with larger increases in women and more sustained response in men. The physiological significance of a sexually dimorphic GH response adds to the growing literature on aggregate GH and may be explained by differences in sex hormones and the structure of the GH cell network.
Department of Kinesiology, Health Promotion and Recreation, University of North Texas, Denton, TX, USA.
Hui Ying
HY
Luk
Department of Human Sciences, The Ohio State University, Columbus, OH, USA. Electronic address: kraemer.44@osu.edu.
William J
WJ
Kraemer
Department of Human Sciences, The Ohio State University, Columbus, OH, USA.
Tunde K
TK
Szivak
Department of Human Sciences, The Ohio State University, Columbus, OH, USA.
Shawn D
SD
Flanagan
Department of Human Sciences, The Ohio State University, Columbus, OH, USA.
David R
DR
Hooper
Human Performance Laboratory, Department of Kinesiology, University of Connecticut, Storrs, CT, USA.
Brian R
BR
Kupchak
Division of Kinesiology and Sport Science, University of South Dakota, Vermillion, SD, USA.
Brett A
BA
Comstock
Department of Health Sciences, School of Science and Engineering, Merrimack College, North Andover, MA, USA.
Courtenay
C
Dunn-Lewis
Department of Kinesiology, Health Promotion and Recreation, University of North Texas, Denton, TX, USA.
Jakob L
JL
Vingren
Department of Human Sciences, The Ohio State University, Columbus, OH, USA.
William H
WH
DuPont
Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA.
Wesley C
WC
Hymer
D000328:Adult; D004220:Disulfides / Q000737:chemistry*; D004797:Enzyme-Linked Immunosorbent Assay; D015444:Exercise / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D019382:Human Growth Hormone / Q000097:blood* / Q000737:chemistry / Q000276:immunology*; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D008297:Male; D055070:Resistance Training; D055815:Young Adult
D004220:Disulfides; D019382:Human Growth Hormone
Bioactivity; Exercise; Glutathione; Growth hormone isoforms; Sex steroids; Sexual dimorphism