Mental Fatigue
Conditions
Keywords
Mental fatigue, Fatigue, Cognitive Fatigue
Brief summary
The goal of this study is to comprehend how mental fatigue could affect human gait. The main questions to answer are: * Does mental fatigue change how people walk? * How long does it take for walking patterns to return to normal after mental fatigue sets in? * What role do constructs like boredom, sleepiness, and motivation play in this relationship? To achieve this, participants will take part in the experiment, split into two sessions: Day 1 (online, about 25 minutes): Practice session. Participants will practice a computer task that will be used to induce mental fatigue in the next session. Day 2 (in-person, about 1.5 to 2 hours): Participants will wear several wearable sensors: motion sensors on their legs, feet, and back, sensor insoles in their shoes, a cap that measures brain activity, and glasses that track eye movement. After sensor placement, participants will walk in a straight line for 10 meters to measure their normal walking pattern. They will then complete a 32-minute computer task designed to induce mental fatigue. Afterward, participants will walk in a straight line for 10 meters again, rest for 3 minutes, and repeat this walk-and-rest cycle 3 more times. Participants will also answer short questions about how tired, bored, and alert they feel throughout the session.
Detailed description
Background: Most prior research on mental fatigue and gait has examined concurrent dual-task walking, in which a cognitive task and walking occur simultaneously. It remains unclear whether gait is altered following (rather than during) a mentally fatiguing task. This study addresses that gap using TloadDback, an adaptive N-back paradigm (Borragán et al., 2016) that individually calibrates cognitive demand to maintain consistent task difficulty across participants, as the mental fatigue induction method. Design: This is a within-subject, repeated-measures design. All primary analyses will be conducted on data collected during the in-person session. Sample size (up to 30 enrolled, target N = 24) was determined via a power analysis using pilot data (N = 5; within-subject design, α = 0.05, power = 0.90). Mental Fatigue Induction Task: TloadDback is administered as a single continuous 32-minute block. Participants view a continuous sequence of number-letter-number stimuli and respond via keypress (odd/even number), when seeing a number, or spacebar (letter repeat), when seeing a letter. Stimulus-presentation speed is individually calibrated during the practice session to the maximum speed at which the participant maintains greater than 85% accuracy, ensuring standardized cognitive demand across participants during the main session. Sensor: Inertial measurement units (IMUs): 8 units, placed at the shanks (2), thighs (2), feet (2), upper spine (1), and lower back (1), capturing spatiotemporal and kinematic gait parameters. Pressure-sensing insoles: worn inside participants' shoes to detect gait events (heel strike, toe-off), complementing IMU-derived timing data. Eye tracker: recording pupil diameter, blink rate, and fixation duration. EEG cap: records brain's electrical voltage fluctuaction to obtain metrics such as frequency band analysis and neural signals related. IMUs and insoles are used primarily to obtain gait parameters, whereas eye tracking and EEG are used only during the mental fatigue-inducing computer task, serving as physiological metrics to corroborate fatigue. Procedures Practice session (remote, online via PsychoPy/Pavlovia): Participants complete a familiarization run of TloadDback for individual speed calibration In-person session pipeline: Demographic questionnaire. Sensor placement: IMUs and insoles Baseline gait trial (10-meter straight-line walk). A 3-minute Psychomotor Vigilance Task (PVT), in which participants respond as quickly as possible by pressing the spacebar each time a visual stimulus (a dot) appears at random inter-stimulus intervals. Sensor placement: Eye tracker and EEG. TloadDback task (32 minutes continuous). Repeat the 3-minute Psychomotor Vigilance Task (PVT). Take off the Eye Tracker and EEG. Post-task gait and recovery assessment: repeated cycles of a straight-line walk trial followed by a 3-minute rest, for a total of 4 post-task walk assessments. Visual Analog Scale (VAS) ratings (fatigue, boredom) are collected at multiple points across the session to track the time course of fatigue and alertness.
Interventions
OTHERMental fatigue
Participants will undergo a mental fatigue induction protocol to examine its effects on gait parameters.
Sponsors
State University of New York at Buffalo
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
TREATMENT
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to 60 Years
Healthy volunteers
Yes
Inclusion criteria
* Adults aged 18-60 years. * Neurotypical individuals with no self-reported history of neurological or cognitive disorders. * Able to walk independently, without an assistive device. * Fluent in English. * Recruitment will aim for gender balance across the sample. * For Day 2, participants must arrive with clean, dry hair, free of styling products (e.g., gels, oils), to ensure adequate EEG electrode contact.
Exclusion criteria
* Outside the age range of 18-60 years. * Self-reported history of neurological or cognitive disorders (e.g., epilepsy, multiple sclerosis, stroke/traumatic brain injury). * Any musculoskeletal condition or injury affecting normal gait. * Use of an assistive device for walking (e.g., cane, walker, brace). * Self-reported photosensitive epilepsy or seizure disorder triggered by screen/visual stimuli. * Non-English speaking. * Day 2 restrictions: less than 6 hours of sleep the night before; caffeine within 2 hours of the session; alcohol within 24 hours of the session.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Subjective fatigue (VAS fatigue rating) | Right at the beginning of the experiment and right after the 32-minutes TloadDback task | Change in self-reported mental fatigue from baseline (PRE) to immediately after the mental fatigue induction task (POST), measured using the Visual Analog Scale for Fatigue (VAS). The VAS is a single-item, self-report scale ranging from 0 to 10, where 0 indicates "not tired at all" and 10 indicates "extremely tired." Higher scores indicate greater self-reported mental fatigue. |
| Change in Mean Reaction Time of the Psychomotor Vigilance Task (PVT) | Right at the beginning and right after the 32-minute TloadDback cognitive task. | Change in mean reaction time on the Psychomotor Vigilance Task from PRE to POST TloadDback, used as a behavioral indicator of mental fatigue-related vigilance decrement. Slower reaction time in the POST, compared to PRE, means more mentally fatigued. |
| Change in Gait Velocity | Right at the beginning and right after the 32-minute TloadDback cognitive task. | Change in gait velocity (meters/second), comparing baseline (PRE) walking trials to post-task (POST) walking trials, measured using inertial measurement units and pressure-sensing insoles. Here, there is no clear pattern; however, we expect participants to slow their gait spede after the fatigue intervention. |
| Change in Gait Cadence | Immediately before and immediately after the 32-minute TloadDback task | Change in gait cadence (steps/minute), comparing baseline (PRE) walking trials to post-task (POST) walking trials, measured using inertial measurement units and pressure-sensing insoles. There is no clear pattern here; however, we are expecting the cadence (steps/minute) to decrease after the fatigue intervention. |
| Change in Stance and Swing Phase Duration | Immediately before and immediately after the 32-minute TloadDback task | Change in stance phase duration and swing phase duration, each expressed as a percentage of the gait cycle, comparing baseline (PRE) walking trials to post-task (POST) walking trials, measured using inertial measurement units and pressure-sensing insoles. Stance phase refers to the portion of the gait cycle when the foot is in contact with the ground, while swing phase refers to the portion when the foot is off the ground and advancing forward. An increase in stance phase duration (with a corresponding decrease in swing phase duration) is generally associated with a more cautious, conservative gait pattern. A decrease in stance phase duration (with a corresponding increase in swing phase) may reflect a faster, less guarded walking pattern. |
| Change in Lower Extremity Joint Angles (Hip, Knee, Ankle) | Immediately before and immediately after the 32-minute TloadDback task | Change in peak hip, knee, and ankle joint angles (degrees) during walking, comparing baseline (PRE) walking trials to post-task (Post) walking trials, measured using inertial measurement units. Joint angles reflect the range of motion at each joint during the gait cycle. A reduction in joint angle range (i.e., smaller peak flexion/extension excursions) is commonly interpreted in the literature as a more restricted or cautious movement strategy, sometimes associated with reduced motor control. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Gait Velocity During Post-Task Recovery | 3, 6, 9, and 12 minutes after the 32-minute TloadDback task | Gait velocity (meters/second), measured at 3, 6, 9, and 12 minutes after the TloadDback task, where participants will rest for 3 minutes, walk 10 meters, and repeat this cycle 4 times. The idea is to examine whether and how walking speed changes as participants rest and recover from mental fatigue. Values will be reported separately for each timepoint. We will be expecting the gait velocity to increase after resting. |
| Gait Cadence During Post-Task Recovery | 3, 6, 9, and 12 minutes after the 32-minute TloadDback task | Gait cadence (steps/minute), measured at 3, 6, 9, and 12 minutes after the TloadDback task, where participants will rest for 3 minutes, walk 10 meters, and repeat this cycle 4 times. The idea is to examine whether and how stepping rate changes as participants rest and recover from mental fatigue. Values will be reported separately for each time point. |
| Stance and Swing Phase Duration During Post-Task Recovery | 3, 6, 9, and 12 minutes after the 32-minute TloadDback task | Stance phase duration and swing phase duration, each expressed as a percentage of the gait cycle, measured at 3, 6, 9, and 12 minutes after the TloadDback task, where participants will rest for 3 minutes, walk 10 meters, and repeat this cycle 4 times. The idea is to examine whether and how the distribution of gait phases changes as participants rest and recover from mental fatigue. Values will be reported separately for stance and swing phase at each timepoint. Stance phase is the gait phase where the foot is on the ground, while swing phase is the gait phase where the foot is moving forward (off the ground). |
| Lower Extremity Joint Angles During Post-Task Recovery (Hip/Knee/Ankle) | 3, 6, 9, and 12 minutes after the 32-minute TloadDback task | Peak hip, knee, and ankle joint angles (degrees) during walking, measured at 3, 6, 9, and 12 minutes after the TloadDback task, where participants will rest for 3 minutes, walk 10 meters, and repeat this cycle 4 times. The idea is to examine whether and how the joint range of motion changes as participants rest and recover from mental fatigue. Values will be reported separately for hip, knee, and ankle at each time point. |
| Self-Reported Mental Fatigue During Post-Task Recovery | 3, 6, 9, and 12 minutes after the 32-minute TloadDback task | Self-reported mental fatigue, measured using the Visual Analog Scale for Fatigue (VAS), at 3, 6, 9, and 12 minutes after the TloadDback task, where participants will rest for 3 minutes, walk 10 meters, and repeat this cycle 4 times. The idea is to examine whether and how perceived fatigue changes as participants rest and recover. The VAS ranges from 0 to 10, where 0 indicates "not tired at all" and 10 indicates "extremely tired"; higher scores indicate greater fatigue. Values will be reported separately for each time point. |
| Change in electroencephalography (EEG) Band Spectral Power | During the 32-minute TloadDback task | Change in relative electroencephalography (EEG) spectral power (%) in theta and alpha frequency bands, recorded during the TloadDback task, providing physiological confirmation of mental fatigue induction. Increases in theta and alpha power, particularly over central and posterior regions, are commonly reported in the literature as indicators of cognitive fatigue accumulation. Values will be reported separately for each frequency band. |
| Change in Pupil Diameter | During the 32-minute TloadDback task | Change in pupil diameter (millimeters), recorded during the TloadDback task using eye-tracking, providing physiological confirmation of mental fatigue induction. A decrease in pupil diameter over the course of the task is commonly reported in the literature as an indicator of increasing mental fatigue. |
| Change in Blink Rate | During the 32-minute TloadDback task | Change in blink rate (blinks per minute), recorded during the TloadDback task using eye-tracking, providing physiological confirmation of mental fatigue induction. An increase in blink rate over the course of the task is commonly reported in the literature as an indicator of increasing mental fatigue. |
Contacts
CONTACTAlexis M Gomez Hernandez
STUDY_CHAIRLora Cavuoto, PhD
University at Buffalo
Outcome results
None listed