Barbosa, Juliana Peroni Abrahão, de Vargas, Wandriane, Del Rosso, Sebastián, Ravagnani, Christiane Coelho, Boullosa, Daniel A., and de Tarso Muller, Paulo (2025) Increased Ventilatory Efficiency in Supramaximal Compared to Graded Exercise in Athletes. Research Quarterly for Exercise and Sport, 96 (2). pp. 265-272.

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Abstract

Background: Supramaximal constant work rate tests (CWR) elicit intense hyperventilation, thus potentially up-shifting ventilation (⩒<inf>E</inf>)-to-carbon dioxide (CO<inf>2</inf>) responses when compared to graded exercise tests (GXT) in athletes. We predicted higher ventilatory efficiency on supramaximal CWR using a new method, challenging the classic orthodox interpretation of an increased ⩒E-⩒CO2> as ventilatory inefficiency. This misinterpretation could make difficult to differentiate between physiological hyperventilation from heart disease conditions in athletes.

Methods: On different days, a GXT and a CWR at 110% of the maximal velocity achieved in the GXT were performed. Twenty-seven athletes completed the two tests and were compared for usual (linear regression) and log-transformed new variables for ventilatory efficiency through paired t-Student statistics.

Results: The ⩒E-⩒CO2 slope (31.4 ± 4.9 vs. 26.2 ± 3.4, p <.001), ⩒/⩒CO2 intercept (7.2 ± 7.5 vs. 2.8 ± 4.2, p <.007), ⩒E/⩒CO/inf nadir (33.0 ± 3.6 vs. 25.4 ± 2.2, p <.001), ⩒CO2-log⩒E slope (10.8 ± 2.9 vs. 6.9 ± 2.2 L*logL−1, p <.001), and η⩒E (36.0 ± 12 vs. 22.8 ± 8.1%, p <.001) values were all significantly higher in the CWR compared to the GXT. We registered a bi-modal nadir response for ⩒E/⩒CO<inf>2 on CWR for 22 out of 27 subjects for the first time. A weak association was observed between ⩒E/⩒CO2 nadir (coefficient of determination ~ 27%) and time to exhaustion.

Conclusions: The new method allows us to improve the quantification and interpretation of ventilatory efficiency in athletes, avoiding misinterpretation due to the up-shifting elicited by the usual ⩒E-⩒CO2 slope and ⩒E/⩒CO2 nadir indices, which may be confounded with ventilatory inefficiency. This study suggests that ventilatory changes underpin better ventilatory efficiency during CWR.

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