Abstract
The effect of single-nanosized oxygen nanobubble water (NBO(2)W), an oxygen-enriched beverage, on exercise performance remains unclear. This double-blind, randomized, placebo-controlled crossover trial investigated whether NBO(2)W 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 NBO(2)W 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 (VO(2) and VCO(2)), 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 VO(2) 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 NBO(2)W intake than after PW intake (mean difference = 3.33 W, p = 0.03). The WR was not significantly different at peak VO(2) or at the onset of blood lactate accumulation. Furthermore, NBO(2)W 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 NBO(2)W consumption in three doses, including that on the day before exercise, did not affect the peak exercise capacity, but improved the WR at LT.