The effect of performing mental exertion during cycling endurance exercise on fatigue indices: sex dependent differences

Abstract

Introduction: Men and women have different performance abilities, where women have greater tolerance for fatigue in long-distance exercise. Part of this greater tolerance may be due, in part, differences in men's and women's mental fatigue capacity during exercise. Thus, the aim of this study was to examine the effect of cycling endurance exercise, along with mental fatigue, on the sex dependent differences in exercise tolerance.

Methods: Twenty-five (15 women and 10 men) cyclists in a randomized, controlled, and crossover protocol performed three experimental sessions. In the first session, the cycling peak power output (PPO) was determined and 65% of PPO was used for intensity of the experimental sessions. In sessions 2 and 3, participants performed Cycling + Mental Exertion (ME) (cycling endurance exercise with a ME-stroop task) and Cycling + Movie (cycling endurance exercise while watching a movie). Serum cortisol concentration and a psychomotor vigilance task (PVT) were measured pre- and post-sessions. During the experimental sessions rate of perceived exertion (RPE) and heart rate (HR) were recorded every 10 min and participants completed the NASA-TLX questionnaire directly following the post- PVT.

Results: Performing Cycling + ME was associated with a longer time to exhaustion (p < 0.05) and higher RPE following 40-70 min in women than men (p < 0.05). Cycling + ME increased HR following 40-70 min in women (p < 0.05). For both men and women cortisol concentration level was higher pre- to post-Cycling + ME with no difference between sexes. Women exhibited faster reaction times compared to men in both pre- and post-sessions.

Discussion: Performing mental exertion with cycling endurance exercise impairs endurance performance. While our findings align with some previous research, we suggest that men may be more prone to mental fatigue; however, further research needed to confirm this.

Keywords: exhaustion; mental fatigue; rate of perceived exertion; stroop task; women cyclists.

FIGURE 1

Overview of experimental protocol.

FIGURE 2

The effects of Cycling + ME and Cycling + Movie on time to exhaustion for Men (white bar) and Women (Grey bar). The asterisk (*) and hash (#) symbols indicate a significant within-subjects contrasts effect for session (p < 0.05). The dollar ($) symbol represents a significant (p < 0.05) difference between sex for Cycling + ME.

FIGURE 3

The effects of Cycling + ME (solid line) and Cycling + Movie (dashed line) on RPE for Men (A) and Women (B). Regardless of session, RPE increased (p < 0.05) both men (represented by a single asterisk) and women (represented by an asterisk and double asterisk). The hash (#) and double hash (##) symbols indicate a significant within-subjects effect for session (p < 0.05). (C, D) indicate the effect of Cycling + ME and Cycling + Movie on RPE for men (solid line) vs. women (dashed line). The dollar ($) symbol represents a significant (p < 0.05) difference between sex from 40 to 70 min during the Cycling + ME session only.

FIGURE 4

The effects of Cycling + ME (solid line) and Cycling + Movie (dashed line) on HR for Men (A) and Women (B). Regardless of session, both men (represented by a single asterisk) and women (represented by a double asterisk) HR increased (p < 0.05). Double hash (##) symbols indicate a significant within-subjects effect for women in Cycling + ME compared to Cycling + Movie (p < 0.05).

FIGURE 5

The effects of Cycling + ME (A) and Cycling + Movie (B) on cortisol concentration for men (white bar) and women (black bar). The asterisk (*) and the double asterisk (**) symbols indicate pre-post significant differences in Cycling + ME and Cycling + Movie for men and women, respectively (p < 0.05).