The validity and reliability of a novel isotope ratio infrared spectrometer to quantify C enrichment of expired breath samples in exercise.

The traditional method to measure CO enrichment in breath involves isotope ratio mass spectrometry (IRMS), which has several limitations such as cost, extensive training, and large space requirements. Here, we present the validity and reliability data of an isotope ratio infrared spectrometer (IRIS)-based method developed to combat these limitations. Eight healthy male runners performed 105 min of continuous running on a motorized treadmill while ingesting various carbohydrate beverages enriched with C and expired breath samples were obtained every 15 min in triplicates.