Muscle Reflex Inhibition in Hypoxic Exercise
Summary
The goal of this interventional study is to compare muscle reflex function under settings of normoxia (normal oxygen level), acute hypoxia (brief oxygen-lack) and chronic hypoxia (long-duration exposure to oxygen-lack). The main question is: Does the muscle reflex adapt to chronic hypoxia? Young, healthy participants will complete light-to-high intensity cycling exercise with and without suppression of the muscle reflex. Suppression of the muscle reflex will be via spinal administration of the opioid Fentanyl. In the control condition, saline will be administered into the spinal space. Participants will complete control (saline) and experimental (Fentanyl) exercise conditions at sea-level (Kelowna, BC, Canada) breathing room air and whilst breathing a lower fraction of oxygen (acute hypoxia). Thereafter, participants will complete the exercise test after living at high altitude (White Mountain, CA, USA) for 2 weeks whilst breathing room air (chronic hypoxia) and breathing a higher fraction of oxygen (restored normoxia).
Timeline
- Start
- 2023-06
- Primary completion
- 2023-12
- Completion
- 2024-06
Publications
- Results Amann M, Proctor LT, Sebranek JJ, Pegelow DF, Dempsey JA. Opioid-mediated muscle afferents inhibit central motor drive and limit peripheral muscle fatigue development in humans. J Physiol. 2009 Jan 15;587(1):271-83. doi: 10.1113/jphysiol.2008.163303. Epub 2008 Nov 17.
- Results Wan HY, Weavil JC, Thurston TS, Georgescu VP, Bledsoe AD, Jessop JE, Buys MJ, Richardson RS, Amann M. The muscle reflex and chemoreflex interaction: ventilatory implications for the exercising human. J Appl Physiol (1985). 2020 Oct 1;129(4):691-700. doi: 10.1152/japplphysiol.00449.2020. Epub 2020 Aug 20.
Drugs
| Evaluation | Drug | Modality | Dose | Route |
|---|---|---|---|---|
| Subject | Fentanyl | Other / unclassified | 0.25 ml | Intrathecal |
Indications
No indication recorded.