title: Effects of systemic hypoxia on human muscular adaptations to resistance exercise training.
abstract: Hypoxia is an important modulator of endurance exercise-induced oxidative adaptations in skeletal muscle. However, whether hypoxia affects resistance exercise-induced muscle adaptations remains unknown. Here, we determined the effect of resistance exercise training under systemic hypoxia on muscular adaptations known to occur following both resistance and endurance exercise training, including muscle cross-sectional area (CSA), one-repetition maximum (1RM), muscular endurance, and makers of mitochondrial biogenesis and angiogenesis, such as peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), citrate synthase (CS) activity, nitric oxide synthase (NOS), vascular endothelial growth factor (VEGF), hypoxia-inducible factor-1 (HIF-1), and capillary-to-fiber ratio. Sixteen healthy male subjects were randomly assigned to either a normoxic resistance training group (NRT, n = 7) or a hypoxic (14.4% oxygen) resistance training group (HRT, n = 9) and performed 8 weeks of resistance training. Blood and muscle biopsy samples were obtained before and after training. After training muscle CSA of the femoral region, 1RM for bench-press and leg-press, muscular endurance, and skeletal muscle VEGF protein levels significantly increased in both groups. The increase in muscular endurance was significantly higher in the HRT group. Plasma VEGF concentration and skeletal muscle capillary-to-fiber ratio were significantly higher in the HRT group than the NRT group following training. Our results suggest that, in addition to increases in muscle size and strength, HRT may also lead to increased muscular endurance and the promotion of angiogenesis in skeletal muscle.
authors.affiliation: Department of Sports Sciences, Japan Institute of Sports Sciences, 3-15-1 Nishigaoka, KitaTokyo, Japan Centre for Physical Activity and Nutrition Research, School of Exercise and Nutrition Sciences, Deakin University, Burwood, Victoria, Australia.
authors.forename: Michihiro
authors.initials: M
authors.lastname: Kon
authors.affiliation: Department of Sports Sciences, Japan Institute of Sports Sciences, 3-15-1 Nishigaoka, KitaTokyo, Japan.
authors.forename: Nao
authors.initials: N
authors.lastname: Ohiwa
authors.affiliation: Department of Sports Sciences, Japan Institute of Sports Sciences, 3-15-1 Nishigaoka, KitaTokyo, Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Honda
authors.affiliation: Department of Sports Sciences, Japan Institute of Sports Sciences, 3-15-1 Nishigaoka, KitaTokyo, Japan.
authors.forename: Takeo
authors.initials: T
authors.lastname: Matsubayashi
authors.affiliation: Department of Sports Sciences, Japan Institute of Sports Sciences, 3-15-1 Nishigaoka, KitaTokyo, Japan.
authors.forename: Tatsuaki
authors.initials: T
authors.lastname: Ikeda
authors.affiliation: Division of Regenerative Medical Engineering, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, BunkyoTokyo, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Akimoto
authors.affiliation: Department of Sports Sciences, Japan Institute of Sports Sciences, 3-15-1 Nishigaoka, KitaTokyo, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Suzuki
authors.affiliation: Department of Sports Sciences, Japan Institute of Sports Sciences, 3-15-1 Nishigaoka, KitaTokyo, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Hirano
authors.affiliation: Centre for Physical Activity and Nutrition Research, School of Exercise and Nutrition Sciences, Deakin University, Burwood, Victoria, Australia.
authors.forename: Aaron P
authors.initials: AP
authors.lastname: Russell
keywords: Capillarization; resistance exercise training; skeletal muscle; systemic hypoxia