Endurance Exercise Performance is Reduced after 6-Hour Dives at 1.35 ATA when Breathing 100% Oxygen Compared to Air

Abstract

ABSTRACT Introduction Long-duration dives on consecutive days reduces muscular performance, potentially impacting military personnel. However, a paucity of data exists on how breathing gases affect endurance performance. This study examined the influence of long-duration diving with different breathing gases on aerobic endurance and handgrip performance. Methods Twenty-three military divers completed a single six-hour dive (SD) and five six-hour dives over consecutive days (DW) with 30-minute cycling intervals using air (AIR, n = 13) or 100% oxygen (OXY, n = 10). Before and after SD and DW, subjects completed a maximum handgrip strength test, handgrip endurance test at 40% maximal strength, and a time to exhaustion run. Results Handgrip endurance decreased after DW in OXY (SD: 1.9 ± 0.0 min vs 1.4 ± 0.3 min) compared to AIR (1.8 ± 0.0 min vs 1.8 ± 0.2 min) (p < 0.001). Run time decreased after SD (Pre: 20.7 ± 10.4 min; Post: 16.6 ± 7.6 min, p = 0.039) and DW (Pre: 21.6 ± 9.0 min; Post: 11.2 ± 4.0 min, p < 0.001) in OXY and after overall diving in AIR (Pre: 26.5 ± 10.2 min; Post: 22.3 ± 7.5 min, p = 0.025). V̇O2 decreased after diving only in AIR (Pre: 42.6 ± 3.4 ml/kg/min; Post: 40.4 ± 3.7 ml/kg/min, p = 0.010). There were no other significant effects. Conclusions Breathing 100% oxygen during long duration dives on consecutive days may exacerbate decreases in aerobic endurance, and impairs handgrip endurance compared to air. Additional research is needed to elucidate mechanisms of action and possible mitigation strategies.