Hypoxia increases muscle hypertrophy induced by resistance training

• Published in: International journal of sports physiology and performance Vol. 5; no. 4; p. 497
• Main Authors: Nishimura, Akinobu, Sugita, Masaaki, Kato, Ko, Fukuda, Aki, Sudo, Akihiro, Uchida, Atsumasa
• Format: Journal Article
• Language: English
• Published: United States 01-12-2010
• Subjects: Adult; Humans; Hypertrophy - physiopathology; Hypoxia - physiopathology; Magnetic Resonance Imaging; Male; Muscle Strength - physiology; Muscle, Skeletal - pathology; Resistance Training; Young Adult
• ISSN: 1555-0265
• DOI: 10.1123/ijspp.5.4.497

Recent studies have shown that low-intensity resistance training with vascular occlusion (kaatsu training) induces muscle hypertrophy. A local hypoxic environment facilitates muscle hypertrophy during kaatsu training. We postulated that muscle hypertrophy can be more efficiently induced by placing the entire body in a hypoxic environment to induce muscle hypoxia followed by resistance training.
Fourteen male university students were randomly assigned to hypoxia (Hyp) and normoxia (Norm) groups (n = 7 per group). Each training session proceeded at an exercise intensity of 70% of 1 repetition maximum (RM), and comprised four sets of 10 repetitions of elbow extension and flexion. Students exercised twice weekly for 6 wk and then muscle hypertrophy was assessed by magnetic resonance imaging and muscle strength was evaluated based on 1RM.
Muscle hypertrophy was significantly greater for the Hyp-Ex (exercised flexor of the hypoxia group) than for the Hyp-N (nonexercised flexor of the hypoxia group) or Norm-Ex flexor (P < .05, Bonferroni correction). Muscle hypertrophy was significantly greater for the Hyp-Ex than the Hyp-N extensor. Muscle strength was significantly increased early (by week 3) in the Hyp-Ex, but not in the Norm-Ex group.
This study suggests that resistance training under hypoxic conditions improves muscle strength and induces muscle hypertrophy faster than under normoxic conditions, thus representing a promising new training technique.