This study investigated whether trait mindfulness in athletes is associated with impairments in neurocognitive function and endurance performance resulting from mental fatigue.
Recent research suggests that mental fatigue by prolonged cognitive tasks would impair neurocognitive functions (e.g., executive functions, brain activity) and sports performance, especially inhibitory control and endurance performance. On the other hand, individuals with higher dispositional mindfulness have been linked to greater athletic performance and cognitive functions. Still, there is little known whether higher dispositional mindfulness counteracts the detrimental effects of mental fatigue on endurance performance and inhibitory control in athletes. Therefore, this study is conducted to investigate whether dispositional mindfulness mediates the effects of mental fatigue on neurocognitive functions and endurance performance in athletes. The qualified participants will visit the lab on two counterbalanced order occasions to complete either a modified incongruent Stroop task (mental fatigue condition, MF) or a modified congruent Stroop task (control condition, CON) for 30 minutes. Before and after each cognitive task, participants will be measured for their subjective mental fatigue by a visual analog scale (VAS). After each cognitive task, inhibitory control and endurance performance will be evaluated by a Flanker task and a graded exercise test (GXT), respectively. Furthermore, the general and athletic dispositional mindfulness will be measured using the Five Facet Mindfulness Questionnaire (FFMQ). Specifically, the targeted primary outcomes are neurocognitive functions (i.e., reaction time, accuracy and ERPs in Flanker task) and endurance performance (i.e., VO2max \& time to exhaustion in GXT); The secondary outcomes are subjective (i.e., VAS score)/objective (i.e., reaction time, accuracy in Stroop task) mental fatigue, motivation in tasks, mood (i.e., BRUMS-C).
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
SCREENING
Masking
NONE
Enrollment
90
In mental fatigue condition, the mental fatigue manipulation will use a modified Stroop task with complete incongruent trials, which is wildly used to induce a mentally fatigued state in previous studies. The Stroop task included four colored words presented in traditional Chinese (i.e., red, green, blue, and yellow), the color of the word will paint inconsistent with the semantic meaning of the word (e.g., red word printed in green). The task consisted of five 6-minute blocks and 1080 incongruent trials for each block. The total duration will be 30-min.
Similar to mental fatigue conditions, the modified Stroop task with complete congruent trials will be used, The Stroop task also included four colored words presented in traditional Chinese (i.e., red, green, blue, and yellow), but the color of the word will paint consistent with the semantic meaning of the word (e.g., red word printed in red) in order to set up the match condition of relative less cognitive demanding for participants. Same with the mental fatigue condition, the task consisted of five 6-minute blocks and 1080 congruent trials for each block. The total duration will be 30-min.
Department of Physical Education and Sport Sciences, National Taiwan Normal University
Taipei, Taiwan
Inhibitory Control: Reaction Time
Inhibitory control will be evaluated by a Flanker task in terms of reaction time in this study, and the types of trials are the congruent (i.e., \> \> \> \> \>) and incongruent (i.e., \< \< \> \< \<). In the Flanker task, participants were presented with five arrows and instructed to respond as quickly and accurately as possible to the direction where the middle arrow is pointing (i.e., left or right).
Time frame: From enrollment to the end of second intervention at 1 week. During Flanker task, up to 15 minutes.
Inhibitory Control: Accuracy
Inhibitory control will be evaluated by a Flanker task in terms of accuracy in this study, and the types of trials are the congruent (i.e., \> \> \> \> \>) and incongruent (i.e., \< \< \> \< \<). In the Flanker task, participants were presented with five arrows and instructed to respond as quickly and accurately as possible to the direction where the middle arrow is pointing (i.e., left or right).
Time frame: From enrollment to the end of second intervention at 1 week. During Flanker task, up to 15 minutes.
Endurance Performance: Time to Exhaustion
The endurance performance in terms of time to exhaustion (TTE) will be assessed by graded exercise test (GXT) with Bruce protocol on treadmill (h/p/cosmos pulsar 3p, Germany). The initial speed and grade of the GXT will be set at 2.74 km/hr with grade of 10% and increase speed and grade every 3 min until participants are volitionally exhausted.
Time frame: From enrollment to the end of second intervention at 1 week. During graded exercise test, up to 30 minutes
Endurance Performance: Maximum Oxygen Consumption
The maximal oxygen consumption (VO2max) throughout the whole GXT will be recorded by a computerized indirect calorimetry system (SensorMedics Vmax 29C, USA), and until the participants reached volitional exhaustion. The VO2max in the study will be defined as the highest 30-s average value of VO2 measured during GXT.
Time frame: From enrollment to the end of second intervention at 1 week. During graded exercise test, up to 30 minutes.
This platform is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional.
Changes in Neuroelectrical Activities
Neuroelectrical activity during the Flanker task was recorded using electroencephalography (EEG) with continuous data acquisition throughout task performance. Changes in neuroelectrical activity were operationalized as differences in event-related potential (ERP) amplitudes during the Flanker task (e.g., N2 and P3 components). The mean amplitudes of the N2 and P3 were quantified within predefined time windows of 250-350 ms and 350-550 ms, respectively, following stimulus onset.
Time frame: From enrollment to the end of second intervention at 1 week. During Flanker task, up to 15 minutes.
Subjective Mental Fatigue
Before, after Stroop task, and after Flanker task, changes in subjective mental fatigue was measured using a visual analog scale for mental fatigue (VAS-MF). Participants were asked the following questions "What is your mental fatigue level now?", and participants could indicate how mental fatigue on a scale from 0 (i.e., no mental fatigue at all) to 100 (i.e., completely mentally exhausted).
Time frame: From enrollment to the end of second intervention at 1 week. Before the Stroop task, immediately after Stroop task and immediately after the Flanker task.
Objective Mental Fatigue: Reaction Time in Stroop Task
During the intervention, the reaction time in both Stroop tasks was calculated as an index of objective mental fatigue.
Time frame: From enrollment to the end of second intervention at 1 week. During Stroop task, up to 30 minutes.
Objective Mental Fatigue: Accuracy in Stroop Task
During the intervention, the accuracy in both Stroop tasks was calculated as an index of objective mental fatigue.
Time frame: From enrollment to the end of second intervention at 1 week. During Stroop task, up to 30 minutes.
Mood State
Mood state was determined by the difference in scores on the Brunel Mood Scale-Chinese (BRUMS-C) between before (i.e., T0) and after (i.e., T1) Stroop task. The BRUMS-C consists of 23 items rated on a 5-point Likert scale and comprises six subscales: anger, confusion, depression, tension, fatigue, and vigor. Each subscale score is calculated as the mean of its corresponding items, with possible scores ranging from 0 to 4. Higher mean scores indicate greater intensity of the respective mood state.
Time frame: Two standardized time points within each experimental session at baseline and post-intervention: T0 (before the Stroop task) and T1 (after the Stroop task).
Motivation
The level of effort exerted by participants during the Flanker task and GXT was assessed using the VAS for motivation (VAS-M). Immediately after completing each task, participants were also asked to mark a 100mm line to rate their motivation to perform at their best (i.e., "How motivated are you to perform to the best of your ability in the task?") on a scale ranging from 0, indicating "not at all," to 100, indicating "extremely motivated."
Time frame: From enrollment to the end of second intervention at 1 week. Immediately after completing Flanker task and GXT.