AUTHOR=Takei Naoya , Muraki Ryuji , Girard Olivier , Hatta Hideo 

TITLE=Inter-individual variability in peripheral oxygen saturation and repeated sprint performance in hypoxia: an observational study of highly-trained subjects

JOURNAL=Frontiers in Sports and Active Living

VOLUME=6

YEAR=2024

URL=https://www.frontiersin.org/journals/sports-and-active-living/articles/10.3389/fspor.2024.1452541

DOI=10.3389/fspor.2024.1452541

ISSN=2624-9367

ABSTRACT=<p>Individual variations in peripheral oxygen saturation (SpO<sub>2</sub>) during repeated sprints in hypoxia and their impact on exercise performance remain unclear despite fixed external hypoxic stimuli (inspired oxygen fraction: FiO<sub>2</sub>). This study examined SpO<sub>2</sub> individual variations during repeated sprints in hypoxia and their impact on exercise performance. Thirteen highly-trained sprint runners performed 10 × 10-s cycle sprints with 30-s passive recoveries in normobaric hypoxia (FiO<sub>2</sub>: 0.150). Mean power output (MPO), post-sprint SpO<sub>2</sub>, and heart rate for each sprint were assessed. Sprint decrement score (S<sub>dec</sub>), evaluating fatigue development, was calculated using MPO variables. Participants were categorized into a high saturation group (HiSat, <italic>n</italic> = 7) or a low saturation group (LowSat, <italic>n</italic> = 6) based on their mean post-sprint SpO<sub>2</sub> (measured 10–15 s after each sprint). Individual mean post-sprint SpO<sub>2</sub> ranged from 91.6% to 82.2%. Mean post-sprint SpO<sub>2</sub> was significantly higher (<italic>P</italic> &lt; 0.001, <italic>d</italic> = 1.54) in HiSat (89.1% ± 1.5%) than LowSat (84.7% ± 1.6%). A significantly larger decrease in S<sub>dec</sub> (<italic>P</italic> = 0.008, <italic>d</italic> = 1.68) occurred in LowSat (−22.3% ± 2.3%) compared to HiSat (−17.9% ± 2.5%). MPO (<italic>P</italic> = 0.342 <italic>d</italic> = 0.55) and heart rate (<italic>P</italic> = 0.225 <italic>d</italic> = 0.67) did not differ between groups. There was a significant correlation (<italic>r</italic> = 0.61; <italic>P</italic> = 0.028) between SpO<sub>2</sub> and S<sub>dec</sub>. In highly-trained sprint runners, individual responses to hypoxia varied widely and significantly affected repeated sprint ability, with greater decreases in SpO<sub>2</sub> associated with larger performance alterations (i.e., larger decrease in S<sub>dec</sub>).</p>