Effects of exercise on peripheral hypercapnic chemosensitivity during high altitude acclimatization

Area of Science:

• Physiology
• Altitude Medicine
• Respiratory Control

Background:

• Sustained high altitude (HA) exposure enhances peripheral chemoreceptor hypercapnic sensitivity.
• Exercise also increases peripheral hypercapnic chemosensitivity (PHC) independently of intensity.

Purpose of the Study:

• To investigate how hypobaric hypoxia at HA influences exercise-induced potentiation of PHC.
• To compare the effects of exercise on PHC at low altitude (LA) and HA.

Main Methods:

• Twenty-one healthy participants underwent maximal and submaximal exercise tests at LA (1,100 m) and HA (3,500 m).
• PHC was assessed at rest and during exercise using hypercapnic inspirates (10% CO2).
• PHC was quantified as the ventilatory (V̇I) over end-tidal PCO2 (PETCO2) response.

Main Results:

• HA resulted in greater resting V̇I and lower resting PETCO2 compared to LA.
• Resting PHC was significantly higher at HA than at LA.
• The exercise-induced increase in PHC was not significantly different between LA and HA.

Conclusions:

• Temporary residence at 3,500 m elevates resting peripheral hypercapnic chemosensitivity.
• Exercise potentiates peripheral hypercapnic chemosensitivity at both altitudes, with a similar magnitude of increase.
• Altitude exposure does not appear to affect the mechanism of exercise-induced PHC potentiation.