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  • Author: Matthew J. Barlow x
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Matthew J. Barlow, Antonis Elia, Oliver M. Shannon, Angeliki Zacharogianni and Angelica Lodin-Sundstrom

Introduction: The purpose of the present study was to assess the effects of acute nitrate (NO3)-rich beetroot juice (BRJ) supplementation on peripheral oxygen saturation (SpO2), heart rate (HR), and pulmonary gas exchange during submaximal static and dynamic apnea. Methods: Nine (six males and three females) trained apneists (age: 39.6 ± 8.2 years, stature: 170.4 ± 11.5 cm, and body mass: 72.0 ± 11.5 kg) performed three submaximal static apneas at 60%, 70%, and 80% of the participant’s current reported personal best time, followed by three submaximal (∼75% or personal best distance) dynamic apneas following the consumption of either a 70-ml concentrated BRJ (7.7 mmol NO3) or a NO3-depleted placebo (PLA; 0.1 mmol NO3) in double-blind randomized manner. HR and SpO2 were measured via fingertip pulse oximetry at the nadir, and online gas analysis was used to assess pulmonary oxygen uptake (V˙O2) during recovery following breath-holds. Results: There were no differences (p < .05) among conditions for HR (PLA = 59 ± 11 bpm and BRJ = 61 ± 12 bpm), SpO2 (PLA = 83% ± 14% and BRJ = 84% ±9%), or V˙O2 (PLA = 1.00 ± 0.22 L/min and BRJ = 0.97 ± 0.27 L/min). Conclusion: The consumption of 7.7 mmol of beetroot juice supplementation prior to a series of submaximal static and dynamic apneas did not induce a significant change in SpO2, HR, and V˙O2 when compared with placebo. Therefore, there is no apparent physiological response that may benefit free divers as a result of the supplementation.