title: Repeated apneas do not affect the hypercapnic ventilatory response in the short term.
abstract: Long-term training of breath-hold diving reduces the hypercapnic ventilatory response (HCVR), an index of the CO(2) sensitivity. The aim of the present study was to elucidate whether also short-term apnea training (repeating apneas with short intervals) reduces the HCVR, thereby being one contributing factor explaining the progressively increasing breath-holding time (BHT) with repetition of apneas. Fourteen healthy volunteers performed a series of five maximal-duration apneas with face immersion and two measurements of the HCVR, using the Read rebreathing method. The BHT increased by 43% during the series of apneas (P < 0.001). However, the slope of the HCVR test was not affected by the series of apneas, being 2.52 (SD 1.27) and 2.24 (SD 1.14) l min(-1) mmHg(-1) in the control test and in the test performed within 2 min after the last apnea of the series, respectively (NS). Thus, a change in the HCVR cannot explain the observed short-term training effect on BHT.
authors.affiliation: Department of Cell and Organism Biology, Lund University, Helgonav. 3B, 223 62 Lund, Sweden. johan.andersson@cob.lu.se
authors.forename: Johan P A
authors.initials: JP
authors.lastname: Andersson
authors.forename: Erika
authors.initials: E
authors.lastname: Schagatay
mesh_terms: D000328:Adult; D001049:Apnea / Q000378:metabolism / Q000503:physiopathology*; D002245:Carbon Dioxide / Q000378:metabolism; D005260:Female; D006801:Humans; D006935:Hypercapnia / Q000378:metabolism / Q000503:physiopathology*; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D012123:Pulmonary Ventilation; D015656:Respiratory Mechanics
chemical_list: D002245:Carbon Dioxide