Peltonen, J. E., Paterson, D. H., Shoemaker, J. K., DeLorey, D. S., duManoir, G. R., Petrella, R. J., & Kowalschuk, J. M. (2008). Effect of supplemental O2 on cerebral and muscle deoxygenation during severe exercise. ACSM 55th Annual Meeting Indianapolis, Presentation Number 1014.

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This study assessed if supplemental O2 (Sup-O2) introduced during normoxic exercise reduces cerebral and muscle tissue deoxygenation and improves exercise performance. Physically active men (N = 8) performed ramp incremental protocols (30 W/min) after a 10-minute warm-up (20 W) on a cycle ergometer to volitional fatigue (T1). The test was repeated (T2) on another day, but the increment in work rate was stopped and held at 30 W below the peak work rate achieved in the first trial while Sup-O2 was initiated. After one minute, the work rate was increased and held at the first trial work rate and the S continued to exercise until volitional fatigue while still breathing Sup-O2. Frontal cerebral cortex and m. vastus lateralis concentration changes from warm-up in deoxyhemoglobin and tissue oxygenation index were determined.

During Sup-O2 in T2, Ss exercised at first trial work rate with improved endurance in seven of eight Ss. Based on individual data, Ss having a lower SpO2% at the end of the ramp phase in T2 experienced a larger increase in total work with Sup-O2. Immediately after its initiation, Sup-O2 increased the cerebral and muscle tissue oxygenation index and reduced muscle deoxyhemoglobin. At fatigue, cerebral deoxyhemoglobin and tissue oxygenation index were similar in T1 and T2, respectively. In muscle, deoxyhemoglobin was similar but tissue oxygenation index was greater in T2. An increased total work in T2 was associated with an attenuated increase in cerebral deoxyhemoglobin from the end of ramp phase to volitional fatigue.

Implication. Sup-O2 reduces cerebral and muscle deoxygenation at least transiently during severe exercise and the length of its effect appears to be tissue specific. Ss who exhibit the largest reduction in SpO2% during incremental exercise have the largest improvement in exercise performance while breathing Sup-O2.

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