Respiratory Muscle O2 Uptake and Deoxygenation During Incremental Exercise to Fatigue: Is There a "Steal"?

To examine RM deoxygenation using near-infrared spectroscopy (NIRS) during incremental RM-specific exercise to fatigue (IE sub(RM)) and compare deoxygenation changes to those seen with incremental leg cycling exercise to fatigue (IE sub(LC)). Healthy men (n, 6; age, 29 + or - 6 yrs (mean + or - SD); ht, 184 + or - 9 cm; mass, 89 + or - 10 kg) performed 4 IE sub(RM) and 1 IE sub(LC). The IE sub(RM) was performed seated, at a breathing frequency of 15 br/min; after 5-min breathing without resistance, inspiratory resistance increased by 50 g every 2-min until the subject was unable to generate the required inspiratory pressure to overcome the added resistance. Peak VO sub(2) in IE sub(RM) was 1.06 L/min ( Delta = 0.58 L/min) and in IE sub(LC) was 4.3 L/min ( Delta = 3.6 L/min). Compared to baseline (BL), peak V sub(E) decreased (p