Abstract
Objective: Cognitive control exertion increases mental fatigue and impairs subsequent physical performance.
Few studies have investigated intervention strategies to attenuate the effects of mental fatigue on exercise behavior.
This study examined heart rate (HR) biofeedback as a moderator of the effects of mental fatigue on
vigorous-intensity exercise performance.
Design: Within-subjects, crossover design.
Methods: Participants (N=36) completed four 20-min sessions of self-paced, cycling exercise. Exercise was
preceded by 10-min high or low cognitive control manipulations crossed with HR biofeedback or no feedback
during exercise in a 2 (high vs. low cognitive control) X 2 (biofeedback vs. no feedback) factorial arrangement.
Participants rated their intended rating of perceived exertion (RPE) and goal commitment prior to and following
the cognitive control manipulations. HR and total work were recorded during each exercise session.
Results: Mental fatigue was significantly greater following high cognitive control exertion, which corresponded
with significant reductions in intended RPE and goal commitment. Participants exercised at a lower average HR
and performed less work in the high cognitive control/no feedback condition, however, with HR biofeedback
following high cognitive control exertion participants attained similar HRs and total work performed to the low
cognitive control conditions, which did not differ.
Conclusions: HR biofeedback improves self-regulation of exercise behavior in a mentally fatigued state. Without
biofeedback, fatigued people may down-regulate exercise intensity. Findings have implications for the use of HR monitoring
devices to improve intensity-based exercise prescription adherence when confronted with barriers
such as mental fatigue.
