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NCT Number: NCT07650903

Mental Fatigue Effects on Posture and Spinal Reflexes

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.

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Key information

Conditions

Mental Fatigue Behavior Behavioral Symptoms Fatigue Pathological Conditions, Signs and Symptoms Signs and Symptoms

Age range

18 year–35 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

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

Treatment and study plan

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.

Primary outcomes

  1. Center of Pressure (CoP) Displacement (Postural Sway)

    Time frame: 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.

  2. Subjective Mental Fatigue

    Time frame: 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

  1. Spinal Reflex Excitability (H-reflex Modulation)

    Time frame: 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.

  2. Surface Electromyography (EMG) Activity of Postural Muscles

    Time frame: 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).

  3. Hip / Leg Movement (IMU Angular Velocity)

    Time frame: 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.

Study contacts

Contact information is provided by the study sponsor or research team.

Sidney Grosprêtre, PhD

CONTACT

[email protected]

+32 (0)2 629 22 22

Sponsors and collaborators

Lead sponsor

Izmir Bakircay University

Other

Collaborators

  • University of Franche-Comté
  • Vrije Universiteit Brussel

Registry information

Official study title

Effects of Mental Fatigue on Posture and Spinal Reflexes Modulations

Important dates

Study start
2026
Primary completion
2026
Study completion
2026
First posted
Jun 16, 2026
Registry last updated
Jun 16, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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