title: Effect of chronic intermittent hypoxia on exercise adaptations in healthy subjects.
abstract: Reduced exercise tolerance has been reported in obstructive sleep apnea syndrome (OSAS) patients, although the associated hypertension, obesity and/or metabolic disorder may underlie this reduction. Therefore, we evaluated the effects of chronic intermittent hypoxia (CIH) in 12 healthy subjects on exercise capacity, cardio-respiratory responses, and substrate oxidation during maximal and sub-maximal exercise. Subjects were exposed to 30 cycles of hypoxia-reoxygenation per hour for 14 nights. Although exercise capacity was unaltered PETCO(2) was reduced and V˙E/V˙CO(2) increased during both maximal and submaximal exercise tests, indicating a hyperventilatory response. Maximal heart rate was lower and diastolic arterial blood pressure (DBP) was higher in the 1st min of recovery after submaximal exercise. Subjects reached maximal lipid oxidation at a higher power output and had decreased blood lactate for a given power output. This suggests that although the metabolic adaptations to CIH in healthy subjects may improve exercise performance, the cardio-pulmonary modifications are similar to those observed in OSAS patients and could limit exercise capacity.
authors.affiliation: UJF, Laboratoire HP2, Grenoble, F-38000, France.
authors.forename: Julia
authors.initials: J
authors.lastname: Tonini
authors.forename: Anne-Sophie
authors.initials: AS
authors.lastname: Michallet
authors.forename: Patrice
authors.initials: P
authors.lastname: Flore
authors.forename: Hugo
authors.initials: H
authors.lastname: Nespoulet
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Pepin
authors.forename: Bernard
authors.initials: B
authors.lastname: Wuyam
authors.forename: Patrick
authors.initials: P
authors.lastname: Levy
authors.forename: Renaud
authors.initials: R
authors.lastname: Tamisier
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D000860:Hypoxia / Q000378:metabolism / Q000503:physiopathology*; D019344:Lactic Acid / Q000097:blood; D015227:Lipid Peroxidation / Q000502:physiology; D008297:Male; D012123:Pulmonary Ventilation / Q000502:physiology; D020181:Sleep Apnea, Obstructive / Q000150:complications / Q000378:metabolism / Q000503:physiopathology; D055815:Young Adult
chemical_list: D019344:Lactic Acid