AUTHOR=Castagna Olivier , Blatteau Jean-Eric , Druelle Arnaud , Amara Jordan , Lacour Jean-René 

TITLE=Oxygen uptake (V˙ O2) and pulmonary ventilation (V˙ E) during military surface fin swimming in a swimming flume: Effects of surface immersion

JOURNAL=Frontiers in Physiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2023.1145204

DOI=10.3389/fphys.2023.1145204

ISSN=1664-042X

ABSTRACT=<p><bold>Introduction</bold>: During military fin swimming, we suspected that oxygen uptake (<inline-formula id="inf3"><mml:math id="m3" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover accent="true"><mml:mi mathvariant="normal">V</mml:mi><mml:mo>˙</mml:mo></mml:mover></mml:mrow></mml:math></inline-formula> O<sub>2</sub>) and pulmonary ventilation (<inline-formula id="inf4"><mml:math id="m4" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover accent="true"><mml:mi mathvariant="normal">V</mml:mi><mml:mo>˙</mml:mo></mml:mover></mml:mrow></mml:math></inline-formula> E) might be much higher than expected. In this framework, we compared these variables in the responses of trained military divers during land cycling and snorkeling exercises.</p><p><bold>Methods</bold>: Eighteen male military divers (32.3 ± 4.2 years; 178.0 ± 5.0 cm; 76.4 ± 3.4 kg; 24.1 ± 2.1 kg m<sup>-2</sup>) participated in this study. They performed two test exercises on two separate days: a maximal incremental cycle test (<italic>land</italic> condition), and an incremental fin swimming (<italic>fin</italic> condition) in a motorized swimming flume.</p><p><bold>Results</bold>: The respective <italic>fin</italic> and <italic>land</italic><inline-formula id="inf5"><mml:math id="m5" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover accent="true"><mml:mi mathvariant="normal">V</mml:mi><mml:mo>˙</mml:mo></mml:mover></mml:mrow></mml:math></inline-formula> O<sub>2max</sub> were 3,701 ± 39 mL min<sup>-1</sup> and 4,029 ± 63 mL min<sup>-1</sup> (<italic>p</italic> = 0.07), these values were strongly correlated (<italic>r</italic><sup>2</sup> = 0.78 <italic>p</italic> &lt; 0.01). Differences in <inline-formula id="inf6"><mml:math id="m6" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover accent="true"><mml:mi mathvariant="normal">V</mml:mi><mml:mo>˙</mml:mo></mml:mover></mml:mrow></mml:math></inline-formula> O<sub>2<italic>max</italic></sub> between conditions increased relative to <italic>l;</italic><inline-formula id="inf7"><mml:math id="m7" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover accent="true"><mml:mi mathvariant="normal">V</mml:mi><mml:mo>˙</mml:mo></mml:mover></mml:mrow></mml:math></inline-formula> O<sub>2max</sub> (<italic>r</italic><sup>2</sup> = 0.4 <italic>p</italic> = 0.01). <italic>Fin</italic><inline-formula id="inf8"><mml:math id="m8" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover accent="true"><mml:mi mathvariant="normal">V</mml:mi><mml:mo>˙</mml:mo></mml:mover></mml:mrow></mml:math></inline-formula> E<sub><italic>max</italic></sub> values were significantly lower than <italic>land</italic><inline-formula id="inf9"><mml:math id="m9" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover accent="true"><mml:mi mathvariant="normal">V</mml:mi><mml:mo>˙</mml:mo></mml:mover></mml:mrow></mml:math></inline-formula> E<sub><italic>max</italic></sub> values (<italic>p</italic> = 0.01). This result was related to both the significantly lower <italic>fin</italic> Vt and <italic>f</italic> (<italic>p</italic> &lt; 0.01 and &lt;0.04, respectively). Consequently, the <italic>fin</italic><inline-formula id="inf10"><mml:math id="m10" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover accent="true"><mml:mi mathvariant="normal">V</mml:mi><mml:mo>˙</mml:mo></mml:mover></mml:mrow></mml:math></inline-formula> E<sub><italic>max</italic></sub>/<inline-formula id="inf11"><mml:math id="m11" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover accent="true"><mml:mi mathvariant="normal">V</mml:mi><mml:mo>˙</mml:mo></mml:mover></mml:mrow></mml:math></inline-formula> O<sub>2<italic>max</italic></sub> ratios were significantly lower than the corresponding ratios for <italic>land</italic> values (<italic>p</italic> &lt; 0.01), and the <italic>fin</italic> and <italic>land</italic><inline-formula id="inf12"><mml:math id="m12" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover accent="true"><mml:mi mathvariant="normal">V</mml:mi><mml:mo>˙</mml:mo></mml:mover></mml:mrow></mml:math></inline-formula> E<sub><italic>max</italic></sub> were not correlated. Other parameters measured at exhaustion—PaO<sub>2</sub>, PaCO<sub>2</sub>, and SO<sub>2</sub> - were similar in <italic>fin</italic> and <italic>land</italic> conditions. Furthermore, no significant differences between <italic>land</italic> and <italic>fin</italic> conditions were observed for peak values for heart rate, blood lactate concentration, and respiratory exchange ratio R.</p><p><bold>Conclusion:</bold> Surface immersion did not significantly reduce the <inline-formula id="inf13"><mml:math id="m13" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover accent="true"><mml:mi mathvariant="normal">V</mml:mi><mml:mo>˙</mml:mo></mml:mover></mml:mrow></mml:math></inline-formula> O<sub>2<italic>max</italic></sub> in trained divers relative to <italic>land</italic> conditions. As long as <inline-formula id="inf14"><mml:math id="m14" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover accent="true"><mml:mi mathvariant="normal">V</mml:mi><mml:mo>˙</mml:mo></mml:mover></mml:mrow></mml:math></inline-formula> O<sub>2</sub> remained below <inline-formula id="inf15"><mml:math id="m15" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover accent="true"><mml:mi mathvariant="normal">V</mml:mi><mml:mo>˙</mml:mo></mml:mover></mml:mrow></mml:math></inline-formula> O<sub>2<italic>max</italic></sub>, the <inline-formula id="inf16"><mml:math id="m16" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover accent="true"><mml:mi mathvariant="normal">V</mml:mi><mml:mo>˙</mml:mo></mml:mover></mml:mrow></mml:math></inline-formula> E values were identical in the two conditions. Only at <inline-formula id="inf17"><mml:math id="m17" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover accent="true"><mml:mi mathvariant="normal">V</mml:mi><mml:mo>˙</mml:mo></mml:mover></mml:mrow></mml:math></inline-formula> O<sub>2<italic>max</italic></sub> was <inline-formula id="inf18"><mml:math id="m18" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover accent="true"><mml:mi mathvariant="normal">V</mml:mi><mml:mo>˙</mml:mo></mml:mover></mml:mrow></mml:math></inline-formula> E higher on land. Although reduced by immersion, <inline-formula id="inf19"><mml:math id="m19" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover accent="true"><mml:mi mathvariant="normal">V</mml:mi><mml:mo>˙</mml:mo></mml:mover></mml:mrow></mml:math></inline-formula> E<sub><italic>max</italic></sub> provided adequate pulmonary gas exchange during maximal fin swimming.</p>