Mental Fatigue Effects on Posture and Spinal Reflexes

NCT07650903 — Not applicable, Not yet recruiting, 26 participants, Izmir Bakircay University

ClinicalTrials Daily · Areas · Conditions · Drugs · Sponsors ·

Effects of Mental Fatigue on Posture and Spinal Reflexes Modulations

Registry	NCT07650903
Status	Not yet recruiting
Phase	Not applicable
Study type	Interventional; randomized, crossover, masking: single, basic science
Enrollment	26 (Estimated)
Sponsor	Izmir Bakircay University (Other); collaborators: Vrije Universiteit Brussel, University of Franche-Comté
Conditions	Mental Fatigue
Interventions	Mental Fatigue Induction, Control Condition (Behavioral)
Dates	start 2026-07-01 (estimated), primary completion 2026-09-01 (estimated), completion 2026-12-01 (estimated), first posted 2026-06-16, last updated 2026-06-16
Locations	1 site in Belgium

-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.

Expand all sections · Collapse all

+Arms and interventions

Arm	Type	Interventions	Description
Control Condition	Experimental	Behavioral: Control Condition	Participants watch a 60-minute neutral documentary of their choice. This condition is designed to control for time, visual input, and arousal without inducing mental fatigue. Postural control and spinal reflex excitability are assessed immediately before and after the task.
Mental Fatigue Condition	Experimental	Behavioral: Mental Fatigue Induction	Participants complete a 60-minute computerized Stroop task designed to induce mental fatigue. The task involves continuous performance of color-word interference trials adjusted to individual capacity. Postural control and spinal reflex excitability are assessed immediately before and after the task.

Mental Fatigue Induction (Behavioral): 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.
Control Condition (Behavioral): 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.

+Outcome measures

Primary outcomes

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 outcomes

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.

+Eligibility

Sex: All, ages: 18 Years to 35 Years, accepts healthy volunteers

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

+Locations (1)

Facility	City	Country	Status
Vrije Universiteit Brussel	Brussels, Pleinlaan 2	Belgium

+Investigators

Bart Roelands, Professor, Study director, Vrije Universiteit Brussel