Mental Fatigue
Conditions
Keywords
Postural control, Center of pressure, Spinal reflex excitability, H-reflex, Stroop task, Electromyography
Brief summary
This randomized crossover study investigates the effects of mental fatigue on postural control and spinal reflex excitability in healthy physically active adults aged 18-35 years. Participants will complete two experimental conditions: a mentally fatiguing Stroop task and a control condition involving passive documentary watching, separated by at least 48 hours. Postural control will be assessed using force plate measures of center of pressure displacement during bipedal and unipedal stance, with and without concurrent cognitive dual-tasking. In parallel, spinal reflex excitability will be evaluated using H-reflex recordings from the triceps surae muscles across sitting and standing postures. The primary aim is to determine whether mental fatigue increases postural sway, particularly in more challenging balance conditions such as single-leg stance. The secondary aim is to examine whether mental fatigue alters the normal modulation of spinal reflex excitability across progressively demanding postural tasks. Additional biomechanical and neuromuscular measures, including EMG activity and hip kinematics, will be recorded to provide insight into underlying control mechanisms. The study will include approximately 26 participants, with each serving as their own control. Data will contribute to understanding how cognitive fatigue influences balance control and spinal-level neuromuscular regulation.
Interventions
BEHAVIORALMental Fatigue Induction
Participants complete a 60-minute computerized Stroop color-word task designed to induce mental fatigue. The task consists of repeated incongruent stimuli requiring rapid and accurate responses, with difficulty individualized based on a prior maximal Stroop performance test. Performance (reaction time and accuracy) is continuously recorded. Subjective mental fatigue is assessed intermittently during the task using a visual analogue scale.
BEHAVIORALControl Condition
Participants watch a 60-minute neutral documentary of their choice. This condition is designed to match the mental fatigue intervention in duration and general sensory engagement without inducing cognitive fatigue. No cognitive task performance is required. Subjective mental fatigue is assessed at equivalent time points using a visual analogue scale.
Sponsors
Izmir Bakircay University
Vrije Universiteit Brussel
University of Franche-Comté
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
SINGLE (Subject)
Intervention model description
Randomized crossover design in which each participant completes both a mental fatigue condition and a control condition in counterbalanced order, separated by a washout period of at least 48 hours. Participants serve as their own control, and outcomes are measured pre- and post-intervention under identical testing conditions.
Eligibility
Sex/Gender
ALL
Age
18 Years to 35 Years
Healthy volunteers
Yes
Inclusion criteria
* Healthy participants aged between 18 and 35 years * Recreational active
Exclusion criteria
* Previous major lower limb injury (last 6 months) * Present neurological or musculoskeletal disorders * Involvement in another concurrent physical or cognitive intervention study
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Center of Pressure (CoP) Displacement (Postural Sway) | Pre-intervention and immediately post-intervention (each experimental session) | Postural sway will be assessed using center of pressure (CoP) displacement area and oscillation parameters measured during bipedal and unipedal stance on a force plate. Higher values indicate greater postural instability. Comparisons will be made between mental fatigue and control conditions, pre- and post-intervention. |
| Subjective Mental Fatigue | During intervention (every 15 minutes) and immediately post-intervention | Subjective mental fatigue will be assessed using a visual analog scale (VAS) ranging from 0 (no fatigue) to 100 (extreme fatigue). |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Spinal Reflex Excitability (H-reflex Modulation) | Pre-intervention and immediately post-intervention across sitting, bipedal stance, and unipedal stance conditions | Spinal reflex excitability will be assessed using H-reflex amplitude (H50 and Hmax), normalized to maximal M-wave (Mmax), recorded from the triceps surae muscles (soleus, medial gastrocnemius, lateral gastrocnemius) during sitting, bipedal stance, and unipedal stance. Changes will be compared between mental fatigue and control conditions. |
| Surface Electromyography (EMG) Activity of Postural Muscles | Continuous recording during postural tasks, pre-intervention and immediately post-intervention (each condition) | Muscle activation will be assessed using root mean square (RMS) electromyography (EMG) activity recorded from the soleus, medial gastrocnemius, lateral gastrocnemius, tibialis anterior, vastus medialis, and multifidus muscles, normalized to maximal M-wave (MMAX). |
| Hip / Leg Movement (IMU Angular Velocity) | Pre-intervention and immediately post-intervention during bipedal and unipedal stance | Hip and leg movements will be assessed using inertial measurement unit (IMU) sensors placed at the proximal femoral epicondyle. Outcome is the resultant angular velocity across movement axes during postural tasks. |
Countries
Belgium
Contacts
CONTACTSidney Grosprêtre, PhD
STUDY_DIRECTORBart Roelands, Professor
Vrije Universiteit Brussel
Outcome results
None listed