Intermittent hypoxia increases ventilation and «sao2» during hypoxic exercise and
hypoxic chemosensitivity.
Katayama, Keisho, Yasutake Sato, Yoshifumi Morotome, Norihiro Shima, Koji Ishida,
Shigeo Mori, and Miharu Miyamura.
1Research Center of Health, Physical Fitness and Sports, and 2Space Medicine
Research Center, Research Institute of Environmental Medicine, Nagoya University,
Nagoya 464«hyphen»8601, Japan
APStracts 8:0012A, 2001.
The purpose of this study was 1) to test the hypothesis that ventilation and arterial oxygen
saturation («sao2») during acute hypoxia may increase during intermittent hypoxia and
remain elevated for a week without hypoxic exposure and 2) to clarify whether the
changes in ventilation and «sao2» during hypoxic exercise are correlated with the change
in hypoxic chemosensivity. Six subjects were exposed to a simulated altitude of 4,500 m
altitude for 7 days (1 h/day). Oxygen uptake («vo2»), expired minute ventilation («ve»),
and «sao2» were measured during maximal and submaximal exercise at 432 Torr before
(Pre), after intermittent hypoxia (Post), and again after a week at sea level (De). Hypoxic
ventilatory response (HVR) was also determined. At both Post and De, «sao2» was
«sim»5% higher than at Pre. Significant increases from Pre were found in HVR and in
ventilatory equivalent for O2 («ve»/«vo2») during submaximal exercise. There were
significant correlations among the changes in HVR at rest and in «ve»/«vo2» and «sao2»
during hypoxic during intermittent hypoxia. We conclude that 1 wk of daily exposure to
1 h of hypoxia significantly improved oxygenation in exercise during subsequent acute
hypoxic up to 1 wk after the conditioning, presumably caused by the enhanced hypoxic
ventilatory chemosensitivity.
Received 5 October 2000; accepted in final form 2 November 2000
APS Manuscript Number A143-0.
Article publication pending J Appl Physiol
ISSN 1080-4757 Copyright 2001 The American Physiological Society.
Published in APStracts on 29 January 2001