Oxygenation of respiratory and locomotor muscles during maximal exercise in two marathon runners

Abstract

A high work of breathing (WOB) associated with pulmonary hyperventilation during physical exercise, may limit sports performance in long-distance runners (e.g. marathon). The assessment of changes in WOB during maximal oxygen consumption test (V̇O2-máx.) allows knowing the intensity of exercise at which the higher WOB limits the delivery of nutrients and oxygen in muscles involved during locomotion. The non-invasive assessment of muscle oxygenation (SmO2) by the interpretation of wavelengths of near-infrared range (Near-Infrared Spectroscopy, NIRS) is a useful and new method to quantify muscle work, used at intercostal muscles (SmO2-m. intercostales) to the WOB, and at locomotor muscles (SmO2-m.vastus laterallis) to external load. Thus, as the intensity of exercise increases, a higher decrease in SmO2 is showed. However, until now is unknown how the ventilatory strategy used to achieve pulmonary hyperventilation affects the SmO2 of these muscle groups, whose muscle work affects them reciprocally through the metabolic reflex. As a report-case, we present the changes in SmO2-m.intercostales (WOB) and peripheral (SmO2-m.vastus laterallis) during the V̇O2-máx. test. in two competitive marathon runners with similar anthropometric characteristics, physical performance, training regimen and sports history. The objective is to give new information for identifying that the ventilatory strategy used during exercise can affect the local oxygenation in muscles with high demand during exercise. To evaluate this aspect, helping to coach improving the exercise performance in their athletes.