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Muscle hypertrophy and metabolic signaling after two different resistance exercises in young men
Author(s) -
Hulmi Juha J,
Walker Simon,
Ahtiainen Juha P,
Nyman Kai,
Kraemer William J,
Häkkinen Keijo
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.1046.6
Subject(s) - muscle hypertrophy , isometric exercise , resistance training , medicine , endocrinology , phosphorylation , biology , microbiology and biotechnology
Muscle mTOR/MAPK signaling is important in mediating hypertrophy/metabolic adaptations to resistance exercise (RE). However, possible differences in signaling responses to a RE protocol designed primarily for large gains in muscle hypertrophy (HRE) and another associated with neural adaptations and limited hypertrophy (maximal strength, MRE), are not well known. Eight untrained men (28.4±3.7yrs) conducted bilateral leg press HRE and MRE protocols in a randomized order with one week between REs. HRE was five sets of ten repetition maximums (5x10RM) and MRE 15x1RM. Six men (26.5±3.6yrs) served as controls. Vastus lateralis muscle biopsies were taken before and 0.5h after RE or resting in controls. The decrease in isometric force and increase in blood lactate after RE, was larger after HRE than after MRE (P<0.05). Western blotting results revealed that no changes were seen in the controls, but the phosphorylation (p) of p70S6K, p85S6K, rpS6, and MAPKs p38α and p38γ were increased after both REs. However, the increase in p‐p70S6K, p‐rpS6 and p‐p38γ were larger after HRE. p‐Erk1 and p‐Erk2 MAPKs increased only after HRE. In conclusion, mTOR/MAPK signaling increases after both maximal strength and hypertrophic protocols but it is greater in the latter, possibly mediating adaptations specific to these types of training. Supported by: DAVID Sports Ltd, the Finnish Cultural Foundation.