Cerebral Responses During Exercise in Hypoxia (CERVOX)

This study has been completed.
Sponsor:
Information provided by (Responsible Party):
University Hospital, Grenoble
ClinicalTrials.gov Identifier:
NCT01614119
First received: May 23, 2012
Last updated: June 4, 2012
Last verified: June 2012
  Purpose

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.


Condition Intervention
Brain Hypoxia
Hypoxia
Other: Hypoxic exposure

Study Type: Interventional
Study Design: Intervention Model: Single Group Assignment
Masking: Single Blind (Subject)
Primary Purpose: Basic Science
Official Title: Evaluation of the Cerebral Responses to Exercise in Hypoxia

Resource links provided by NLM:


Further study details as provided by University Hospital, Grenoble:

Primary Outcome Measures:
  • Change in voluntary activation [ Time Frame: Baseline and after 4h of exercise ] [ Designated as safety issue: No ]
    Maximum voluntary activation level measured using TMS


Secondary Outcome Measures:
  • Change in tissue oxygenation [ Time Frame: Baseline and after 4 hours of exercise ] [ Designated as safety issue: No ]
    Muscle and cerebral oxygenation measured with NIRS and fMRI


Enrollment: 30
Study Start Date: June 2010
Study Completion Date: July 2011
Primary Completion Date: July 2011 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: Sportsmen
One single group of active healthy subjects was investigated
Other: Hypoxic exposure
Subjects breath either normoxic or hypoxic (FiO2 = 12%) gas mixture
Other Name: Hypoxia (FiO2 = 12%)

Detailed Description:

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 (fMRI) will be used to evaluate cerebral activation, the perfusion imaging arterial spin labelling (ASL) nuclear magnetic resonance method will assess regional cerebral perfusion, near infrared spectroscopy (NIRS) will allow measurement of cerebral oxygenation, measurement of motor evoked potential in response to transcranial magnetic stimulation (TMS) will assess the cortical excitability, measurement of the level of central activation (assessed by TMS) and the electromyographic (EMG) signals will evaluate the motor command. Moreover, to account for the effect of the muscle mass involved during exercise and the duration of hypoxic exposure, brain adaptation to exercise in hypoxia will be assessed for motor task involving small (thumb adduction) or large (knee extension, cycle ergometry) muscle groups as well as for acute (<1 hour) or prolonged hypoxic exposure (several hours: 6 hours). This multi-technical approach will be possible through this collaborative project between three partners experts in brain function investigation and exercise physiology (Institut Fédératif de Recherche 'RMN Biomédical et Neurosciences' Joseph Fourier University and University Hospital, Grenoble; 'Exercise Physiology' Laboratory, University Hospital, St Etienne; 'Motor Efficiency and Deficiency Laboratory', Montpellier I University, Montpellier).

The investigators hypothesise that hypoxia would enhance the cerebral perturbation associated with a given fatiguing exercise, i.e. would induce greater reduction in cerebral blood and cerebral oxygenation, greater reduction in cortical excitability and central activation as well as larger reduction in central command, and this particularly when a large muscle mass is involved as well as when hypoxic exposure is prolonged.

This project aims to renew our vision of the limitation of human exercise performance as well as our understanding of exercise tolerance under hypoxemic conditions. The later is relevant for sport and altitude medicine dealing with exercise and altitude tolerance, as well as for diseases characterised by hypoxemia and exercise intolerance such as respiratory diseases like chronic obstructive pulmonary diseases for example.

  Eligibility

Ages Eligible for Study:   18 Years to 50 Years
Genders Eligible for Study:   Male
Accepts Healthy Volunteers:   Yes
Criteria

Inclusion Criteria:

  • Male
  • 18-50 yrs
  • No cardiovascular, respiratory or neuromuscular disorders

Exclusion Criteria:

  • Cardiovascular, respiratory or neuromuscular diseases
  • Contraindication for TMS and MRI
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT01614119

Locations
France
Grenoble University Hospital
Grenoble, France, 38042
Sponsors and Collaborators
University Hospital, Grenoble
Investigators
Principal Investigator: Bernard Wuyam, MD PhD University Hospital, Grenoble
  More Information

No publications provided

Responsible Party: University Hospital, Grenoble
ClinicalTrials.gov Identifier: NCT01614119     History of Changes
Other Study ID Numbers: 1002, 2010-A00121-38
Study First Received: May 23, 2012
Last Updated: June 4, 2012
Health Authority: France: Afssaps - Agence française de sécurité sanitaire des produits de santé (Saint-Denis)

Keywords provided by University Hospital, Grenoble:
Cerebral
Oxygenation
Performance
Exercise

Additional relevant MeSH terms:
Hypoxia, Brain
Brain Diseases
Central Nervous System Diseases
Nervous System Diseases

ClinicalTrials.gov processed this record on October 19, 2014