Perceived Exertion Is Elevated By A Dual-task Of Cognitive Performance And Aerobic Exercise

Abstract

In many sports (e.g., football, lacrosse, rugby, etc.), the need to perform a dual-task (e.g., decision-making during exercise) is unavoidable. Purpose: Given that prolonged continuous performance of a cognitively demanding task increases mental fatigue, we hypothesized that a sustained cognitive effort superimposed during aerobic exercise would compound the increased rating of perceived exertion (RPE). Methods: Twenty-one healthy, young males (aged 22 ± 2 yrs; VO2 peak = 46 ± 5 ml/kg/min) performed two trials [i.e., exercise-cognition (EX-Cog) and exercise-only (EX)] in a randomised-crossover design. In EX-Cog trial, participants performed 50-min moderate-intensity (60% peak oxygen uptake) cycling exercise and sustained 50-min Stroop task, simultaneously. In EX trial, participants performed 50-min moderate-intensity cycling exercise. RPE was assessed via the Borg scale during the final 10 seconds of exercise in both conditions. Mental fatigue (visual analog scale) and heart rate (HR; HR monitor) in response to exercise were also recorded. RPE was analyzed using Wilcoxon signed-rank test. Changes in mental fatigue and HR in response to exercise were analyzed using a two-way (trial × time) repeated-measures analysis of variance. Results: The elevations in mental fatigue and HR were identical during both trials (both P < 0.05). In contrast, RPE was higher during EX-Cog (EX-Cog median 15; IQR 15.0 to 17.0 vs. EX median 15; IQR 14.0 to 16.5, P = 0.012). Conclusions: These findings indicate that dual-tasking increases perceived exertion yet fails to incur additional mental fatigue or cardiovascular demand which may have implications for decision-making during sport.