Physiological and cognitive responses to hyperoxic exercise in full water submersion

Area of Science:

• Exercise Physiology
• Hyperbaric Medicine
• Cognitive Neuroscience

Background:

• Combined hyperoxia and exercise benefits are known in laboratory settings.
• Underwater environments (e.g., SCUBA diving) present unique conditions that may modify these effects.
• Understanding these interactions is crucial for safety and performance in diving scenarios.

Purpose of the Study:

• To investigate the effects of varying inspiratory oxygen partial pressures (P_IO₂) during underwater fin-swimming at different exercise intensities.
• To assess the impact on physiological parameters like ventilation (V̇_E) and blood lactate ([Lac^-]).
• To evaluate cognitive functions, specifically inhibitory control, under these conditions.

Main Methods:

• Fifteen participants performed underwater fin-swimming at 25%, 45%, and 75% heart rate reserve (HRR).
• Tests were conducted under three different inspiratory oxygen partial pressures (29 kPa, 56 kPa, 140 kPa).
• Measurements included continuous V̇_E, post-exercise gas analysis, blood lactate, and Eriksen Flanker tasks for cognitive assessment.

Main Results:

• Higher P_IO₂ (140 kPa and 56 kPa) significantly reduced V̇_E during moderate and vigorous exercise compared to normobaric conditions (29 kPa).
• Blood lactate, post-exercise V̇CO₂, and swimming velocity remained unaffected by P_IO₂.
• Vigorous exercise (75% HRR) led to faster reaction times but reduced accuracy in inhibitory control tasks, independent of P_IO₂.

Conclusions:

• Underwater hyperoxia can reduce ventilation during exercise, potentially due to altered chemoreceptor sensitivity.
• Cognitive effects observed underwater differ from laboratory findings, highlighting the role of sport-specific environmental factors.
• P_IO₂ did not influence cognitive performance or key physiological markers like lactate, suggesting exercise intensity is a primary driver of these outcomes.