The Effects of Physical and Mental Fatigue on Time Perception

The subjective perception of time holds a foundational significance within the realm of human psychology and our conceptualizations of reality and how we elucidate the chronological progression of events within our lives. While there have been some studies examining the effects of exercise on time perception during the exercise period, there are no studies investigating the effects of fatiguing exercise on time perception after the exercise intervention. This study aimed to investigate the effects of physical and mental fatigue on time estimates over 30-seconds (5-, 10-, 20-, and 30-seconds) immediately after exercise and 6-minutes after the post-test. Seventeen healthy and recreationally active volunteers (14 males, 3 females) were subjected to three conditions: physical fatigue, mental fatigue, and control. All participants completed a familiarization and three 30-minute experimental conditions (control, physical fatigue (cycling at 65% peak power output), and mental fatigue (Stroop task for 1100 trials) on separate days. Heart rate and body temperature were recorded at the pre-test, start, 5-, 10-, 20-, 30-seconds of the interventions, post-test, and 6-min follow-up. Rating of perceived exertion (RPE) was recorded four times during the intervention. Time perception was measured prospectively (at 5-, 10-, 20-, and 30-seconds) at the pre-test, post-test, and 6-minute follow-up. Physical fatigue significantly (p=0.001) underestimated time compared to mental fatigue and control conditions at the post-test and follow-up, with no significant differences between mental fatigue and control conditions. Heart rate, body temperature, and RPE were significantly (all p=0.001) higher with physical fatigue compared to mental fatigue and control conditions during the intervention and at the post-test. This study demonstrated that cycling-induced fatigue led to time underestimation compared to mental fatigue and control conditions. It is crucial to consider that physical fatigue has the potential to lengthen an individuals perception of time estimates in sports or work environments.