Maximum effort breath-hold times for males and females of similar pulmonary capacities during sudden face-only immersion at water temperatures from 0 to 33°C

For non breath-hold-trained males and females matched for pulmonary capacity and body size, the effects of sex, water temperature, and end-tidal gas tensions were studied for their potential influences on breath-holding ability. Maximum breath-hold time (BHTmax) was measured a total of 546 times in 13 males and 13 females, each repeating 3 trials of sudden face immersion (i.e., no prior hyperventilation) in water at 0, 5, 10, 15, 20, and 33 degrees C and in an air control condition (AIR). End-tidal carbon dioxide (PETCO2) and oxygen (PETO2) gas tensions were measured before and after breath-holding in a subset of 11 males and 11 females. For BHTmax there was no main effect of sex (p = 0.20), but there was a main effect of immersion condition (p < 0.001). Relative to pre-immersion rest values, end-tidal gas tensions were significantly higher in males than in females (p <= 0.05) and significantly lower at decreased water temperatures relative to AIR (p <= 0.05). In conclusion, for these matched groups (i) sex did not influence BHTmax; (ii) irrespective of sex, decreases in water temperature at 0, 5, 10, and 15 degrees C gave proportionate decreases of BHTmax; (iii) significantly greater deviations in both PETCO2 and PETO2 following breath-holding were evident in males relative to females; and (iv) irrespective of sex, there were significantly smaller changes in both PETCO2 and PETO2 at lower water temperatures relative to AIR, with or without removing the variance due to breath holding.