Monitoring the Effect of Mental Fatigue on Physical Performance Using Wearable Sensors and Physiological Parameters

Condition(s) studied

Investigational drug(s) / intervention(s)

Mental Fatigue: Mental fatigue (MF) is a psychobiological state characterized by feelings of tiredness and/or a measurable decline in performance following prolonged or intense cognitive activity.

Study summary

Mental fatigue (MF) negatively affects both cognitive and physical performance, increasing the risk of errors in high-stakes environments such as sports and surgery. Traditional methods to assess MF rely on subjective self-report scales, which are prone to bias, or on complex brain measurements (e.g. EEG) that are impractical outside laboratory settings. This study aims to develop a real-time, objective monitoring method for MF using wearable physiological sensors. The study will recruit healthy, trained runners (18-35 years old) who will complete both an MF-inducing cognitive task (Stroop test) and a control condition (watching a documentary) in a randomized, counterbalanced, crossover design. Heart rate variability, respiration rate, and pupil metrics will be continuously recorded using wearable devices. Machine learning models will be used to predict MF-level as well as the effect of MF on physical performance (5-km time trial on a treadmill) using the physiological data as input.

Eligibility

Primary outcome measure(s)

• Heart rate variability time-domain parameters — Continuously during the cognitive intervention and control condition on the study day (approximately 75 minutes).
  Root mean square of successive differences \[RMSSD\], standard deviation of normal-to-normal intervals \[SDNN\] in milliseconds.
• Heart rate variability frequency-domain parameters — Continuously during the cognitive intervention and control condition on the study day (approximately 75 minutes).
  Low-frequency (LF), High-frequency (HF) in milliseconds squared (ms²) and Low/high-frequency ratio \[LF/HF\]
• Respiration rate — Continuously during the cognitive intervention and control condition on the study day (approximately 75 minutes).
  Respiration rate (RR) will be measured as the number of breaths per minute (breaths/min)
• Pupil diameter — Continuously during the cognitive intervention and control condition on the study day (approximately 75 minutes).
  Pupil diameter (PD) will be measured in millimeters (mm) as an index of autonomic nervous system activity.
• Blinking rate — Continuously during the cognitive intervention and control condition on the study day (approximately 75 minutes).
  Blinking rate (BR) will be measured as the number of spontaneous blinks per minute (blinks/min)
• Eyelid opening — Continuously during the cognitive intervention and control condition on the study day (approximately 75 minutes).
  Eyelid opening (EO) will be measured as the vertical distance between the upper and lower eyelid in millimeters (mm).
• Cognitive Performance Accuracy — At baseline (pre-intervention), during the 60-minute cognitive intervention, and immediately after completion of the intervention on the study day (approximately 70 minutes total).
  Cognitive performance will be evaluated using a Go/No-Go task. The task begins with a general instruction screen, followed by the simultaneous presentation of two types of stimuli: a Go or No-Go signal and a left or right directional indicator. This results in four possible combinations: GoRight, GoLeft, NoGoRight, and NoGoLeft. When a Go signal appears, participants must respond by pressing the arrow key corresponding to the left or right direction. In contrast, when a No-Go signal is displayed, participants must withhold any response, regardless of the directional cue. This paradigm is designed to assess attention, response inhibition, working memory, and executive functions, all of which are known to be negatively affected by MF. Accuracy in percentage (%) of correct answers on this Go/No-Go task as well as accuracy during the Stroop intervention task will be measured.
• Cognitive Performance Reaction Time — At baseline (pre-intervention), during the 60-minute cognitive intervention, and immediately after completion of the intervention on the study day (approximately 70 minutes total).
  Cognitive performance will be evaluated using a Go/No-Go task. The task begins with a general instruction screen, followed by the simultaneous presentation of two types of stimuli: a Go or No-Go signal and a left or right directional indicator. This results in four possible combinations: GoRight, GoLeft, NoGoRight, and NoGoLeft. When a Go signal appears, participants must respond by pressing the arrow key corresponding to the left or right direction. In contrast, when a No-Go signal is displayed, participants must withhold any response, regardless of the directional cue. This paradigm is designed to assess attention, response inhibition, working memory, and executive functions, all of which are known to be negatively affected by MF. Reaction time (RT) will be measured in milliseconds (ms) as the latency between stimulus onset and the participant's behavioral response (button press) on the Go/No-Go task and during the Stroop intervention task.
• Physical performance: Time to Completion — Immediately after completion of the 60-minute cognitive intervention, during a single 5-km treadmill time trial on the study day (approximately 20 minutes).
  Participants will perform a 5-km running time trial on a treadmill to assess endurance performance under MF. The treadmill will be set at a 1% gradient, following established protocols to replicate outdoor running conditions. Before beginning the time trial, participants will complete a standardized warm-up for 5 minutes. To maintain self-paced running conditions, participants will receive real-time feedback on the distance covered but will not be provided with information about running speed or elapsed time. Researchers will remain present but will not offer verbal encouragement or pacing cues to ensure that the effort remains internally regulated. Once the 5-km distance is completed, participants will immediately stop running and step onto the treadmill's side platforms. The total time elapsed will be recorded.

Trial sites (1)

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