Positive effects of single-nanosized oxygen nanobubble water on exercise tolerance: A randomized crossover trial

The effect of single-nanosized oxygen nanobubble water (NBO₂W), an oxygen-enriched beverage, on exercise performance remains unclear. This double-blind, randomized, placebo-controlled crossover trial investigated whether NBO₂W intake influences lactate threshold (LT), a key indicator of aerobic exercise performance. The participants (n = 20; age, 47.4 ± 5.0 years; female, 12) consumed either NBO₂W or placebo water (PW) immediately followed by an incremental exercise test on an ergometer for symptom-limited exhaustion. During the test, the heart rate, respiratory gas analysis (VO₂ and VCO₂), tissue oxygen index (TOI), and blood lactate level were continuously monitored. The first administered beverage was randomly selected, with both participants and investigators blinded to the beverages. A washout period of minimum seven days was implemented between the two tests. The mean peak VO₂ was 26.13 ± 5.05 mL/min/kg. Eighteen (90 %) participants exercised less than four times per week, indicating limited exercise habits. The average washout period was 9.7 ± 5.0 days. The work rate (WR) at LT was significantly higher after NBO₂W intake than after PW intake (mean difference = 3.33 W, p = 0.03). The WR was not significantly different at peak VO₂ or at the onset of blood lactate accumulation. Furthermore, NBO₂W intake significantly increased the lactate levels 5 min post-exercise (mean difference = 0.88, p = 0.01) and decreased the TOI (mean difference = -3.8, p = 0.01). Short-term NBO₂W consumption in three doses, including that on the day before exercise, did not affect the peak exercise capacity, but improved the WR at LT.