Trained distance runners combine lower ventilatory equivalents with a deeper, slower breathing pattern and a markedly longer isocapnic buffering phase, so buffering duration may index the ventilatory strategy adopted during progressive exercise.
Key Findings
Results
Trained runners had lower minimum ventilatory equivalents for oxygen and carbon dioxide than recreationally trained runners.
Minimum ventilatory equivalent for oxygen: 24.70 ± 2.37 in trained vs 28.58 ± 1.73 in recreationally trained runners (P < 0.001).
Minimum ventilatory equivalent for carbon dioxide: 28.06 ± 2.24 vs 31.39 ± 2.38 (P = 0.002).
Sample was 24 1500-m runners (12 trained, 12 recreationally trained; six men and six women per group) who completed a continuous incremental treadmill ramp test to volitional exhaustion (0.5 km·h⁻¹ increase every 30 s) with breath-by-breath gas exchange.
Results
The slope of the ventilatory equivalent for carbon dioxide did not differ between trained and recreationally trained runners.
The abstract reports P = 0.609 for the group difference in the ventilatory equivalent for carbon dioxide slope.
Results
End-tidal oxygen pressure was lower and end-tidal carbon dioxide pressure higher in trained runners at the gas exchange threshold, respiratory compensation point, and a third exercise stage.
Both group differences were P < 0.001 across all three stages.
Stages were compared across the gas exchange threshold, the respiratory compensation point, and peak exercise.
Results
The magnitude of the end-tidal carbon dioxide difference between groups varied by sex and exercise stage.
The abstract reports an interaction with P < 0.001.
Each group included six men and six women.
Results
The isocapnic buffering phase lasted markedly longer in trained than in recreationally trained runners.
Duration was 3.46 ± 0.46 min in trained vs 1.79 ± 0.39 min in recreationally trained runners (P < 0.001).
Effect size was large (partial η² = 0.82).
Results
Isocapnic buffering duration was strongly positively associated with mean tidal volume and strongly inversely associated with mean breathing frequency.
Correlation with mean tidal volume: r = 0.981.
Correlation with mean breathing frequency: r = -0.905.
Both correlations had P < 0.001.
Conclusions
Trained runners adopted a deeper, slower breathing pattern with greater ventilatory economy.
Trained runners combined lower ventilatory equivalents with a deeper, slower breathing pattern at peak exercise.
The authors suggest buffering duration may index the ventilatory strategy used during progressive exercise.
What This Means
This study compared how two groups of 1500-m runners, 12 well-trained and 12 recreationally trained (equal numbers of men and women), breathed while running on a treadmill that got gradually faster until they could not continue. Researchers measured the gases they breathed in and out to see how efficiently they breathed and how long they could keep their blood carbon dioxide level steady during rising exercise intensity (the 'isocapnic buffering' phase).
Trained runners needed less air for the same oxygen use and carbon dioxide output, meaning they breathed more economically. They also held their carbon dioxide level steady for much longer: about 3.5 minutes versus about 1.8 minutes in recreational runners. Longer steady periods were closely linked to taking deeper, slower breaths. The rate at which breathing rose relative to carbon dioxide output did not differ between groups.
This research suggests that the length of this steady phase may reflect a breathing strategy that distance training promotes, namely deeper and slower breaths. Because the study was a cross-sectional comparison of a small group, it cannot show that training caused these differences.
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Shahidi S, Seyrek E, Metin G. (2026). Prolonged isocapnic buffering and economical breathing in trained distance runners.. Respiratory physiology & neurobiology. https://doi.org/10.1016/j.resp.2026.104657