Differences in muscle performance during fatigue may explain the differences in motoneurone excitability between acute and chronic hypoxia
Letter to the Editor
Blackwell Publishing Ltd
School of Medical and Health Sciences
We have with great interest read the paper by Ruggiero and colleagues, which explored the effects of acclimatization to hypoxia on motoneurone excitability during fatigue(Ruggiero et al. 2018). Cervicomedullary evoked potentials (CMEPs), an index of motoneurone excitability, were reported during fatiguing submaximal contractions in normoxia, acute hypoxia (environmental chamber), and after 7–14 days of chronic hypoxic exposure at altitude in Nepal. The study shows that the normal decline in CMEPs that occurs during fatigue of the elbow ﬂexor muscles does not occur after chronic exposure to hypoxia. The paper suggests that after acclimatization, there is heightened motoneurone responsiveness during fatiguing exercise, particularly when compared to acute hypoxia. The authors attributed the heightened motoneurone responsiveness to increased noradrenaline release.