Sex-Differences in the Oxygenation Levels of Intercostal and Vastus Lateralis Muscles During Incremental Exercise
Maximiliano Espinosa‐Ramírez, Eduardo Moya, Felipe Araya-Román, Santiago Riquelme-Sánchez, Guido Rodriguez-García, W. Darlene Reid, Ginés Viscor, Oscar F. Araneda, Luigi Gabrielli, Felipe Contreras–Briceño
Abstract
This study aimed to examine sex differences in oxygen saturation in respiratory (SmO 2 - m.intercostales ) and locomotor muscles (SmO 2 - m.vastus lateralis ) while performing physical exercise. Twenty-five (12 women) healthy and physically active participants were evaluated during an incremental test with a cycle ergometer, while ventilatory variables [lung ventilation ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="INEQ2"><mml:mover accent="true"><mml:mtext>V</mml:mtext><mml:mo>.</mml:mo></mml:mover></mml:math> E), tidal volume (Vt), and respiratory rate (RR)] were acquired through the breath-by-breath method. SmO 2 was acquired using the MOXY ® devices on the m.intercostales and m.vastus lateralis . A two-way ANOVA (sex × time) indicated that women showed a greater significant decrease of SmO 2 - m.intercostales , and men showed a greater significant decrease of SmO 2 - m.vastus lateralis . Additionally, women reached a higher level of ΔSmO 2 - m.intercostales normalized to <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="INEQ3"><mml:mover accent="true"><mml:mtext>V</mml:mtext><mml:mo>.</mml:mo></mml:mover></mml:math> E (L⋅min –1 ) ( p &lt; 0.001), whereas men had a higher level of ΔSmO 2 - m.vastus lateralis normalized to peak workload-to-weight (watts⋅kg –1 , PtW) ( p = 0.049), as confirmed by Student’s t -test. During an incremental physical exercise, women experienced a greater cost of breathing, reflected by greater deoxygenation of the respiratory muscles, whereas men had a higher peripheral load, indicated by greater deoxygenation of the locomotor muscles.