Clinical Trial: Cerebral Responses During Exercise in Hypoxia

Study Status: Completed
Recruit Status: Completed
Study Type: Interventional

Official Title: Evaluation of the Cerebral Responses to Exercise in Hypoxia

Brief Summary: While the exercise responses are classically described at the cardiorespiratory and muscle levels, recent data suggest that the brain is also significantly stressed by exercise and may even participate to performance limitation. In hypoxia in particular, cerebral responses to exercise may be altered and promote performance reduction during endurance exercise. In the present study, the investigators used innovative approaches to assess cerebral perturbations associated with exercise in hypoxia.

Detailed Summary:

In the classical paradigm of exercise physiology, cardio-respiratory capacity and muscle fatigue are though to set the limit of exercise tolerance. However, there are experimental situations where it is not possible to explain exercise performance limitation using this classical paradigm, and it is therefore necessary to look for an alternative. Recent investigations highlight changes associated with exercise in the brain, e.g. changes in cerebral perfusion, cerebral oxygenation and neuron excitability. Also, several results suggest that in some conditions, the central nervous system fails to drive the motoneurons adequately, i.e. the so called central fatigue. However, the phenomenon of central limitation to exercise and its underlying neurophysiological mechanisms are still to clarify. Cerebral metabolism and neurohumoral responses during fatiguing exercise are therefore to investigate in order to propose a new paradigm able to explain exercise limitation. Among the conditions where the classical paradigm of exercise performance limitation does not appear to suit the actual observations, exercise under hypoxic environment appears to be particularly challenging. Some data suggest indeed that the cerebral response to exercise may be substantially modified in hypoxia compared to normoxia.

Hence, in the present project, the investigators aim to evaluate the effect of hypoxia on brain adaptation to exercise in healthy human. In particular, the objective is to assess the brain neurophysiological response to a fatiguing exercise, including cerebral perfusion and oxygenation, cerebral activation, cortical excitability as well as the resultant motor command while inhaling normoxic or hypoxic gas mixtures. To fulfil these objectives, complementary methodological approaches will be used during exercise both normoxic and hypoxic conditions: functional magnetic resonance imaging (fM
Sponsor: University Hospital, Grenoble

Current Primary Outcome: Change in voluntary activation [ Time Frame: Baseline and after 4h of exercise ]

Original Primary Outcome: Same as current

Current Secondary Outcome: Change in tissue oxygenation [ Time Frame: Baseline and after 4 hours of exercise ]

Original Secondary Outcome: Same as current

Information By: University Hospital, Grenoble

Dates:
Date Received: May 23, 2012
Date Started: June 2010
Date Completion:
Last Updated: June 4, 2012
Last Verified: June 2012