It has been reported that resistance training under hypoxic condition caused greater increases in muscle size and strength compared with that of normoxic condition (Nishimura et al. 2010). We recently demonstrated that resistance exercise induced a greater anabolic hormone response under hypoxia than that under normoxia (Kon et al., 2010). However, the influence of hypoxic resistance training on skeletal muscle gene expressions related to muscular hypertrophy is still not clarified. Here, we examined the effect of resistance training under systemic hypoxia on gene expressions in human skeletal muscle. Methods: Sixteen healthy male subjects were randomly assigned to either the normoxic resistance training group (n = 7) or the hypoxic (14.4% oxygen) resistance training group (n = 9); they performed 8-wk resistance exercise training. The resistance exercise consisted of two consecutive exercises (bench-press and bilateral leg-press), each with 10 repetitions for 5 sets at 70% of one-repetition maximum. All the sets and exercises were separated by 90-s rest intervals. Muscle biopsy samples from the vastus lateralis muscle were analysed for insulin-like growth factor 1 (IGF-1), IGF-1 receptor (IGF-1R), myostatin, andogen receptor (AR) mRNA expressions. Results: There were no significant differences in the mRNA expressions of IGF-1, IGF-1R, myostatin, and AR between the groups, although the mRNA expressions of IGF-1 and AR were significantly increased, and the mRNA expression of myostatin was significantly reduced after training in both the groups (P < 0.05). The IGF-1R mRNA expression was unchanged after training. Discussion: Present results are consistent with the results of the previous studies (Kim et al. 2007, Lamon et al. 2009). However, resistance training under hypoxic condition did not affect IGF-1, IGF-1R, myostatin, and AR mRNA expressions in human skeletal muscle compared with that of normoxic condition. Hypoxia may not influence the responses of IGF-1, IGF- 1R, myostatin, and AR mRNA expressions to resistance training.
© Copyright 2012 17th Annual Congress of the European College of Sport Science (ECSS), Bruges, 4. -7. July 2012. Veröffentlicht von Vrije Universiteit Brussel. Alle Rechte vorbehalten.