Authors
Tomas Venckunas, Justas Achramavicius, Hakan Westerblad, Viktorija Maconyte, Ilona Judita Zuoziene, Inga Pravdinskiene, Carsten Lundby, Arvydas Stasiulis
Published in
European journal of applied physiology. Jul 03, 2026. Epub Jul 03, 2026.
Abstract
Performance in endurance sports is generally linked to aerobic capacity, but this link is less clear in swimming due to its technical complexity and constricted breathing periods. Here, we studied the effect of a moderate acute reduction in blood oxygen transport capacity on middle-distance swimming performance.
In a double-blind, randomized crossover design, national-level swimmers (6 men, 6 women; 20 ± 2 years; FINA score 604 ± 105) completed two 200 m front crawl swimming time-trials (TT) on average six days apart, either 30 min after rebreathing moderate (men: 1.5 ml·kg- 1, women: 1.2 ml·kg- 1; CO) or small (SHAM) CO dose. Capillary blood lactate and hemoglobin CO binding (%HbCO) were measured before and after the TT.
HbCO was ~ 9% in CO and ~ 3% in SHAM. Analysis at the group level showed 1.5 ± 1.6% longer TT times in CO than in SHAM in men (136.6 ± 6.5 vs. 134.5 ± 6.2 s; p = 0.018), whereas there was no significant difference in women. The average increase in blood lactate during TT (10.5-13.5 mmol·l- 1) did not differ between conditions. Analysis at the individual level showed longer swimming TT times in the CO than in the SHAM condition (range: 1.1 to 5.0 s) in eight of the twelve participants.
We observed a small negative effect of moderate acute hypoxemia on middle-distance swimming speed in male national-level swimmers, which will have a limited impact on a population basis but can be highly important for an individual competitive swimmer.
PMID:
42397570
Bibliographic data and abstract were imported from PubMed on 03 Jul 2026.
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