title: Breath-hold diving: respiratory function on the longer term.
abstract: OBJECTIVE
  Extensive breath-hold (BH) diving imposes high pulmonary stress by performing voluntary lung hyperinflation maneuvers (glossopharyngeal insufflation, GI), hyperinflating the lung up to 50% of total lung capacity. Breath-hold durations of up to 10 min without oxygen support may also presume cerebral alterations of respiratory drive. Little is known about the long-term effects of GI onto the pulmonary parenchyma and respiratory adaptation processes in this popular extreme sport.
  
  
  METHODS
  Lung function assessments and subsequent measures of pulmonary static compliance were obtained for 5 min after GI in 12 elite competitive breath-hold divers (BHD) with a mean apnea diving performance of 6.6 yr. Three-year follow-up measurements were performed in 4 BHD. Respiratory drive was assessed in steady-state measurements for 6% and 9% CO2 in ambient air.
  
  
  RESULTS
  Short-term pulmonary stress effects for static compliance during GI (13.75 L·kPa) could be confirmed in these 12 divers without exhibiting permanent changes to the lungs' distensibility (7.41 L·kPa) or lung function parameters as confirmed by the follow-up measurements and for 4 BHD after 3 yr (P>0.05). Respiratory drive was significantly reduced in these BHD revealing a characteristic breathing pattern with a significant increase in VE and mouth occlusion pressure (P0.1) between free breathing and 6% CO2, as well as between 6% CO2 and 9% CO2 (all P<0.001).
  
  
  CONCLUSIONS
  BH diving with performance of GI does not permanently alter pulmonary distensibility or impair ventilatory flows and volumes. A blunted response to elevated CO2 concentrations could be demonstrated, which was supportive of the hypothesis that CO2 tolerance is a training effect due to BH diving rather than being an inherited phenomenon.
authors.affiliation: Department of Pneumology, University Hospital Freiburg, Freiburg, Germany. stephan.walterspacher@uniklinik-freiburg.de
authors.forename: Stephan
authors.initials: S
authors.lastname: Walterspacher
authors.forename: Tobias
authors.initials: T
authors.lastname: Scholz
authors.forename: Kay
authors.initials: K
authors.lastname: Tetzlaff
authors.forename: Stephan
authors.initials: S
authors.lastname: Sorichter
mesh_terms: D000328:Adult; D001049:Apnea / Q000503:physiopathology*; D004242:Diving / Q000009:adverse effects*; D006801:Humans; D008168:Lung / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D012129:Respiratory Function Tests; D015656:Respiratory Mechanics / Q000502:physiology