Repeated apneas and hypercapnic ventilatory response before and after apnea training

Area of Science:

• Physiology
• Respiratory Control
• Exercise Physiology

Background:

• Habitual exposure to carbon dioxide (CO2) is theorized to reduce ventilatory sensitivity.
• Hypercapnic ventilatory response (HCVR), measured by CO2 sensitivity (ΔVE/ΔPetCO2), may be blunted by such exposure.
• This study investigated the impact of apnea training on HCVR.

Purpose of the Study:

• To test the hypothesis that HCVR decreases after repeated breath-hold maximal efforts (RBHE) and apnea training.
• To compare changes in HCVR between a control breath-hold (CBH) group and a novice breath-hold (NBH) group.
• To determine if short-term apnea training affects ventilatory response to CO2.

Main Methods:

• Two groups (CBH and NBH) underwent four laboratory visits.
• HCVR tests were performed before and after RBHE sessions.
• The NBH group engaged in 14 days of daily RBHE training.
• Breath-hold time (BHT) and CO2 sensitivity were measured.

Main Results:

• Apnea training significantly increased BHT by approximately 46% in the NBH group.
• No significant differences in CO2 sensitivity slopes were observed among experimental conditions or between groups.
• Measured CO2 sensitivity values remained consistent throughout the study.

Conclusions:

• HCVR was not reduced after RBHE or 14 days of apnea training, despite increased BHT.
• The development of hypercapnic ventilatory dullness appears to be a complex process requiring more than 14 days of training.
• Short-term apnea training does not impair the immediate ventilatory response to CO2.