Impacts of Concurrent Cognitive Challenge on Aerobic Performance During Graded Exercise
Authors: Trent Jacob A. , Stone Brandon L. , Ashley John D. , Sun Jongjoo , Shelley Joseph H. , Beneda-Bender Madison , McCollum Duncan L. , Fuenzalida Eugenia , Kellawan J. Mikhail 
Published: April 2020

IntroductionBoth sport and tactical performance relies on one’s ability to complete high levels of physical exercise simultaneously engaging in complex cognitive tasks (e.g. executive function). Several studies have found that combined cognitive tasks and muscle contractions can induce an earlier onset of fatigue and impair performance. However, it remains unclear if cognitive stress attenuates whole body dynamic exercise performance.PurposeTo determine if the addition of a cognitive task would limit maximal whole‐body exercise performance.Methods16 healthy Reserve Officer Training Corp cadets (19.6 ± 2 yrs, 5 Female) completed 3 graded exercise tests (GxT) separated by ≥ 24 hrs. The first GxT began at 3.5 mph, 0% grade increasing 2% every 2‐min until 16%, where speed increased by 0.5 mph every 2‐min until volitional fatigue. The next two GxTs (EFET, executive function exercise test) were identical to the first GxT while simultaneously completing an executive function test (Cedar Operator Workload Assessment Tool) on an iPad fixed to the treadmill. Heart rate (HR), respiration rate (RR), arterial blood saturation (SpO2) (Equivital Life monitoring system) and cerebral oxygenation (calculated tissue saturation index, TSI) using Near infrared spectroscopy was recorded throughout each test. Performance was determined by the number of stages completed. All data during the two EFET tests were averaged to form a singular response.ResultsData are mean ± SD, effect size calculated as Ω2. Concurrent executive function test and exercise did not significantly affect the number of stages completed when compared to the GxT (Stages completed, GxT= 8.6 ± 1.3, EFET= 8.5± 1.2, p= 0.2). However, 5 of 16 subjects completed fewer stages during EFET compared to GxT (Stages completed, GxT= 9.2± 1.3, EFET= 8.5± 1.1, p<0.01) were labelled Non‐Resilient (NR). The other 11 subjects who completed the same or more stages during the EFET were labeled Resilient (R) (Stages completed, GxT= 8.4± 1.3, EFET= 8.5± 1.2, p= 0.10). The R group had similar TSI responses between trials (p= 0.3, Ω2 = 0.01) while the NR group had a greater decay in TSI at the highest intensities during EFET compared to GxT (p<0.01, Ω2 = 0.11). Post hoc was unable to identify disparities at specific intensities (90% 61.9± 1.7 vs 63.7± 1.3 d=1.2 p>0.05, 100% 59.9± 1.7 vs 62.1± 1.3 d= 1.4 p>0.05, EFET vs. GxT, respectively). No difference in HR during EFET trials compared to GxT for NR (p=0.9, Ω2= 0.02) or R (p=0.5, Ω2 = 0.06) groups. No other variables differed between trials and groups.ConclusionConcurrent cognitive task does not impact graded exercise performance. However, our data suggests inter‐individual responses exist, where that some individuals maintain performance, while others cannot. The large effect size indicates NR were unable to sustain TSI during EFET. Therefore, maintenance of exercise performance with cognitive task seems to be related to one’s ability to preserve brain oxygenation during high intensity exercise.