Supplemental Oxygen Does Not Influence Self-selected Work Rate at Moderate Altitude

Introduction It is well known that supplemental oxygen can increase aerobic power output during high-intensity and/or maximal efforts at moderate altitude, yet the effects on self-selected work rate during lower-intensity, submaximal exercise are unknown. We reasoned that if the degree of arterial oxygen saturation (SaO2) influences teleoanticipatory regulation of power output, supplemental oxygen given at moderate altitude would increase average power output during exercise performed at self-selected work rates corresponding to RPE 9 (very light) and 13 (somewhat hard). Methods Twenty-three subjects (17 males, 6 females) completed one familiarization [fraction of inspired O2 (FIO2)=0.209] and two blinded, experimental trials (FIO2=0.209 and FIO2=0.267). In each trial, subjects self-regulated their work rate on a cycle ergometer to maintain RPE 9 for 5 min and RPE 13 for 10 min, before performing an incremental step test to exhaustion (25 W/min). Oxygen consumption (VO2) and SaO2 via pulse oximetry (SpO2) were continuously monitored. Subjects were asked to guess the experimental condition after each stage of the protocol. Results Supplemental oxygen increased SpO2 throughout exercise (~4%; P0.14). Conclusions Small increases in inspired oxygen concentration at moderate altitude are imperceptible and do not appear to influence selection of submaximal work rates at RPE ≤ 13. Corresponding Address: Andrew W. Subudhi, Department of Biology, 1420 Austin Bluffs Parkway, Colorado Springs, CO 80918, Phone: 719-255-3938, Email: asubudhi@uccs.edu This project was internally funded by the UCCS Department of Biology. The data presented represent clear, honest, original work without fabrication, falsification, or manipulation. The results of the study and viewpoints presented do not constitute endorsement by the American College of Sports Medicine. CONFLICTS OF INSTEREST: The authors report no conflicts of interest between this work and others. Accepted for Publication: 3 October 2018 © 2018 American College of Sports Medicine

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