Cerebral Oxygenation Dynamics During Incremental Exercise: Comparison of Arm Cranking and Leg Cycling.

Abstract

This study aimed to compare cerebral oxyhemoglobin (O2Hb) levels during incremental exercise by cycling vs. arm cranking in 12 healthy adult men aged 20.8±0.2years old. O2Hb was measured by near-infrared spectroscopy. Regions of interest included the left and right prefrontal cortices (LtPFC and RtPFC, respectively), the left and right premotor cortices (LtPMC and RtPMC, respectively), and the supplementary motor area (SMA) bilaterally. After 4 min of rest, 4 min of warm-up was performed by using ergometer followed by incremental exercise (increasing work rate by 5W/min for arm cranking and 20W/min for cycling exercise). All values were averaged every tenth of the participant's exercise time period from beginning of incremental exercise to end point. At the middle exercise intensity (50% exercise time), the averaged O2Hb values obtained at all regions of interest seemed to be higher during arm cranking exercise as compared to cycling; however, there were no significant differences between two types of exercise. At the end point of incremental exercise (100% exercise time), the O2Hb obtained at all regions of interest was significantly higher during arm cranking exercise compared to cycling (LtPFC 0.081±0.019 vs. -0.001±0.013mM·cm, RtPFC 0.076±0.021 vs. 0.018±0.015mM·cm, SMA 0.012±0.040 vs. 0.040±0.016mM·cm; arm cranking vs. cycling; p<0.05, respectively). We conclude that exercise-induced cerebral oxygenation is greater with arm cranking than with leg cycling.