Stuart Goodall1, Rosie Twomey2, Markus Amann3. 1. Faculty of Health and Life Sciences, Northumbria University, Newcastle, UK. 2. School of Sport and Service Management, University of Brighton, Eastbourne, UK. 3. Department of Medicine, University of Utah, Salt Lake City, UT, USA.
Abstract
PURPOSE: To outline how hypoxia profoundly affects neuronal functionality and thus compromise exercise-performance. METHODS: Investigations using electroencephalography (EEG) and transcranial magnetic stimulation (TMS) detecting neuronal changes at rest and those studying fatiguing effects on whole-body exercise performance in acute (AH) and chronic hypoxia (CH) were evaluated. RESULTS: At rest during very early hypoxia (<1-h), slowing of cerebral neuronal activity is evident despite no change in corticospinal excitability. As time in hypoxia progresses (3-h), increased corticospinal excitability becomes evident; however, changes in neuronal activity are unknown. Prolonged exposure (3-5 d) causes a respiratory alkalosis which modulates Na+ channels, potentially explaining reduced neuronal excitability. Locomotor exercise in AH exacerbates the development of peripheral-fatigue; as the severity of hypoxia increases, mechanisms of peripheral-fatigue become less dominant and CNS hypoxia becomes the predominant factor. The greatest central-fatigue in AH occurs when SaO2 is ≤75%, a level that coincides with increasing impairments in neuronal activity. CH does not improve the level of peripheral-fatigue observed in AH; however, it attenuates the development of central-fatigue paralleling increases in cerebral O2 availability and corticospinal excitability. CONCLUSIONS: The attenuated development of central-fatigue in CH might explain, the improvements in locomotor exercise-performance commonly observed after acclimatisation to high altitude.
PURPOSE: To outline how hypoxia profoundly affects neuronal functionality and thus compromise exercise-performance. METHODS: Investigations using electroencephalography (EEG) and transcranial magnetic stimulation (TMS) detecting neuronal changes at rest and those studying fatiguing effects on whole-body exercise performance in acute (AH) and chronic hypoxia (CH) were evaluated. RESULTS: At rest during very early hypoxia (<1-h), slowing of cerebral neuronal activity is evident despite no change in corticospinal excitability. As time in hypoxia progresses (3-h), increased corticospinal excitability becomes evident; however, changes in neuronal activity are unknown. Prolonged exposure (3-5 d) causes a respiratory alkalosis which modulates Na+ channels, potentially explaining reduced neuronal excitability. Locomotor exercise in AH exacerbates the development of peripheral-fatigue; as the severity of hypoxia increases, mechanisms of peripheral-fatigue become less dominant and CNS hypoxia becomes the predominant factor. The greatest central-fatigue in AH occurs when SaO2 is ≤75%, a level that coincides with increasing impairments in neuronal activity. CH does not improve the level of peripheral-fatigue observed in AH; however, it attenuates the development of central-fatigue paralleling increases in cerebral O2 availability and corticospinal excitability. CONCLUSIONS: The attenuated development of central-fatigue in CH might explain, the improvements in locomotor exercise-performance commonly observed after acclimatisation to high altitude.
Authors: S D Sandiford; H J Green; T A Duhamel; J D Schertzer; J D Perco; J Ouyang Journal: Am J Physiol Regul Integr Comp Physiol Date: 2005-04-28 Impact factor: 3.619
Authors: Simranjit K Sidhu; Joshua C Weavil; Tyler S Mangum; Jacob E Jessop; Russell S Richardson; David E Morgan; Markus Amann Journal: Clin Neurophysiol Date: 2016-10-26 Impact factor: 3.708
Authors: Bhargavi Natarajan; Vikas Arige; Abrar A Khan; S Santosh Reddy; Manoj K Barthwal; Nitish R Mahapatra Journal: Hypertens Res Date: 2020-09-11 Impact factor: 3.872
Authors: Jeffrey W F Aldous; Bryna C R Chrismas; Ibrahim Akubat; Ben Dascombe; Grant Abt; Lee Taylor Journal: Front Physiol Date: 2016-01-12 Impact factor: 4.566