Effect of acute hypoxia on muscle blood flow, VO2p, and [HHb] kinetics during leg extension exercise in older men

• Published in: European journal of applied physiology 2013-07, Vol.113 (7), p.1685-1694
• Main Authors: Zerbini, Livio, Spencer, Matthew D., Grey, Tyler M., Murias, Juan M., Kowalchuk, John M., Schena, Federico, Paterson, Donald H.
• Format: Article
• Language: English
• Subjects: Age Factors; Aged; Biomedical and Life Sciences; Biomedicine; Case-Control Studies; Exercise - physiology; Heart Rate; Human Physiology; Humans; Hypoxia - blood; Hypoxia - metabolism; Hypoxia - physiopathology; Kinetics; Leg - physiology; Male; Muscle, Skeletal - blood supply; Muscle, Skeletal - metabolism; Muscle, Skeletal - physiology; Occupational Medicine/Industrial Medicine; Original Article; Oxygen Consumption; Pulmonary Ventilation; Regional Blood Flow; Sports Medicine
• ISSN: 1439-6319; 1439-6327
• DOI: 10.1007/s00421-013-2599-6

The adjustment of pulmonary oxygen uptake ( V O 2p ), heart rate (HR), limb blood flow (LBF), and muscle deoxygenation [HHb] was examined during the transition to moderate-intensity, knee-extension exercise in six older adults (70 ± 4 years) under two conditions: normoxia (FIO 2  = 20.9 %) and hypoxia (FIO 2  = 15 %). The subjects performed repeated step transitions from an active baseline (3 W) to an absolute work rate (21 W) in both conditions. Phase 2 V O 2p , HR, LBF, and [HHb] data were fit with an exponential model. Under hypoxic conditions, no change was observed in HR kinetics, on the other hand, LBF kinetics was faster (normoxia 34 ± 3 s; hypoxia 28 ± 2), whereas the overall [HHb] adjustment ( ) was slower (normoxia 28 ± 2; hypoxia 33 ± 4 s). Phase 2 V O 2p kinetics were unchanged ( p