Dietary nitrate increases middle cerebral artery mean velocity (MCA Vmean) during aerobic exercise but it remains unclear if this is true with the simultaneous inclusion of a cognitively demanding task. Therefore, our aim was to investigate whether nitrate supplementation would influence exercise-induced changes in MCA Vmean, and cognitive performance. In a double blind randomized crossover design, 12 healthy adults consumed two 70 ml doses of either beetroot juice or placebo two hours prior to exercise. Subjects then completed four 8-min workloads of exercise set to elicit 30%, 50%, 70%, and 85% of heart rate reserve (HRR) on a cycle ergometer. Reaction time and accuracy was assessed during a modified version of the color Stroop task, with simple and complex (incongruent) response types, in the last 3 min of each workload. MCA Vmean (Transcranial Doppler) was monitored throughout. MCA Vmean displayed a typical relationship with exercise intensity, but was significantly elevated with beetroot, especially during the complex Stroop task, at 70% (p=0.001, d=0.47) and 85% HRR (p=0.027, d=0.74). Reaction time was not statistically different between conditions regardless of the difficulty level. However, beetroot may have contributed to increased accuracy in the complex task (p=0.059) whilst cycling. These preliminary results suggest that dietary nitrate elevates MCA Vmean during a combined exercise and cognitive challenge, which may be related to improved accuracy during the most demanding tasks.
|Number of pages||4|
|Publication status||Published - 1 Jan 2015|
|Event||Experimental Biology 2015 - Boston Convention and Exhibition Center, Boston, United States|
Duration: 28 Mar 2015 → 1 Apr 2015