Features of glossopharyngeal breathing in breath-hold divers
One technique employed by competitive breath-hold divers to increase diving depth is to hyperinflate the lungs with glossopharyngeal breathing (GPB). Our aim was to assess the relationship between measured volume and pressure changes due to GPB. Seven healthy male breath-hold divers, age 33 ( 8 ) [mean (SD)] years were recruited. Subjects performed baseline body plethysmography (TLCPRE). Plethysmography and mouth relaxation pressure were recorded immediately following a maximal GPB maneuver at total lung capacity (TLC) (TLCGPB) and within 5 min after the final GPB maneuver (TLCPOST). Mean TLC increased from TLCPRE to TLCGPB by 1.95 (0.66) liters and vital capacity (VC) by 1.92 (0.56) liters ( P < 0.0001), with no change in residual volume. There was an increase in TLCPOST compared with TLCPRE of 0.16 liters (0.14) ( P < 0.02). Mean mouth relaxation pressure at TLCGPB was 65 (19) cmH2O and was highly correlated with the percent increase in TLC ( R = 0.96). Breath-hold divers achieve substantial increases in measured lung volumes using GPB primarily from increasing VC. Approximately one-third of the additional air was accommodated by air compression.