A1 Journal article (refereed)
Effects of Acute Loading Induced Fatigability, Acute Serum Hormone Responses and Training Volume to Individual Hypertrophy and Maximal Strength during 10 Weeks of Strength Training (2023)

Räntilä, A., Ahtiainen, J. P., & Häkkinen, K. (2023). Effects of Acute Loading Induced Fatigability, Acute Serum Hormone Responses and Training Volume to Individual Hypertrophy and Maximal Strength during 10 Weeks of Strength Training. Journal of Sports Science and Medicine, 22, 559-570. https://doi.org/10.52082/jssm.2023.559

JYU authors or editors

Räntilä, Aapo
Ahtiainen, Juha
Häkkinen, Keijo

Publication details

All authors or editors: Räntilä, Aapo; Ahtiainen, Juha P.; Häkkinen, Keijo

Journal or series: Journal of Sports Science and Medicine

ISSN: 1303-2968

Publication year: 2023

Publication date: 01/09/2023

Volume: 22

Pages range: 559-570

Publisher: Uludag University

Publication country: Turkey

Publication language: English

DOI: https://doi.org/10.52082/jssm.2023.559

Publication open access: Openly available

Publication channel open access: Open Access channel

Publication is parallel published (JYX): https://jyx.jyu.fi/handle/123456789/88966

Abstract

This study investigated whether a strength training session-induced acute fatigue is related to individuals’ strength training adaptations in maximal force and/or muscle hypertrophy, and whether acute responses in serum testosterone (T) and growth hormone (GH) concentrations during the training sessions would be associated with individual neuromuscular adaptations. 26 males completed the 10-week strength-training intervention, which included fatiguing dynamic leg press acute loading bouts (5 x 10 RM) at weeks two, four, six, and ten. Blood samples were collected before and after the loading and after 24h of recovery for serum T, GH, and cortisol (C) concentrations at weeks 2, 6, and 10. The cross-sectional area of the vastus lateralis was measured by ultrasonography. Isometric force measurements were performed before and immediately after loadings, and loading-induced acute decrease in maximal force was reported as the fatigue percentage. The subjects were split into three groups according to the degree of training-induced muscle hypertrophy after the training period. Increases in isometric force were significant for High Responders (HR, n = 10) (by 24.3 % ± 17.2, p = 0.035) and Medium Responders (MR, n = 7) (by 23.8 % ± 5.5, p = 0.002), whereas the increase of 26.2 % (±16.5) in Low Responders (LR, n = 7) was not significant. The amount of work (cm + s) increased significantly at every measurement point in all the groups. A significant correlation was observed between the fatigue percentage and relative changes in isometric force after the training period for the whole group (R = 0.475, p = 0.022) and separately only in HR (R = 0.643, p = 0.049). Only the HR group showed increased acute serum GH concentrations at every measurement point. There was also a significant acute increase in serum T for HR at weeks 6 and 10. HR showed the strongest correlation between acute loading-induced fatigue and isometric force gains. HR was also more sensitive to acute increases in serum concentrations of T and GH after the loading. Acute fatigue and serum GH concentrations may be indicators of responsiveness to muscle strength gain and, to some extent, muscle hypertrophy.

Keywords: strength training; fatigue (biological phenomena); muscles; testosterone; growth hormones

Free keywords: strength training; muscle hypertrophy; strength gains; individual differences; acute loading-induced fatigue; serum responses of testosterone and growth hormone

Fields of science: