Elizabeth Rogers1, Cassandra Beattie1, Britton Scheuermann1, Halle Brin1, Jennifer Murphy2, Carl Ade1 and Katie Heinrich1

1Kansas State University, Manhattan, KS

2Technological University – Dublin, Dublin, Ireland

Background: This study replicated Salam et al. (2018), investigating the effect of mental fatigue (MF) on power asymptote (critical power [CP]) and curvature constant (W') of the power-duration relationship, which dictate tolerance to severe-intensity exercise. We tested the original authors’ hypothesis that a mentally fatiguing task would decrease CP and/or the W' during cycling exercise.

Methods: Trained cyclists recruited for the present study initially completed an incremental cycling test for determination of the gas exchange threshold (GET) and peak power output. Over four sessions, participants completed one of two 30-min mental tasks: control (i.e., sat and waited quietly) or a mentally fatiguing task (i.e., modified Stroop test where participants were shown one of four words – red, green, blue, yellow – in a different color and had to press a corresponding key for the word color, not the word meaning). In each condition, four separate severe-intensity exercise bouts to exhaustion, either 40, 60, 80, or 100% of the difference between GET and peak power, were performed. To determine CP and W’, the work rate for each intensity and the corresponding time-to-fatigue within each participant were fit to a hyperbolic and linear regression (1/time) model.

Results: Ten trained male cyclists (age 40.2 +-12 years) completed an incremental cycling test and subsequent visits to determine CP and W’. CP was not significantly different between the control condition (256.1 + 11.24 W) and the Stoop condition (251.2 + 10.48 W; p > 0.1). Similarly, W’ showed no significant difference between conditions (control: 16018 + 1607 J vs Stroop: 15370 + 964.7 J; p > 0.5).

Conclusion: The current findings demonstrate that CP and W’ are not impaired with a prior mental fatiguing task. These results partially align with the original findings, in that CP was not altered. However, findings of the present study contrast with the original findings, which suggested that W’ was altered by physiological factors.

Acknowledgments: This study was funded by a Kansas State University College of Human Ecology Undergraduate Research Award and Office of Undergraduate Research and Creative Inquiry Research Award.

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