NCT07846618 · Florida Institute for Human and Machine Cognition
Acute Mental Fatigue and Muscle Strength
What this study is about
This study will investigate the acute effects of mental fatigue on lower-extremity muscle strength and limb symmetry in healthy young adults. Participants will complete lower-extremity strength testing before and after a standardized computer-based mental fatigue protocol involving tasks of attention, reaction time, concentration, and working memory.
View original scientific description
This study will investigate the acute effects of mental fatigue on lower-extremity muscle strength and limb symmetry in healthy young adults. Participants will complete lower-extremity strength testing before and after a standardized computer-based mental fatigue protocol involving tasks of attention, reaction time, concentration, and working memory. Muscle strength and limb symmetry will be assessed using isokinetic dynamometry, with muscle activity measured using surface electromyography. Participants will also complete subjective measures of mental fatigue, sleepiness, mental effort, and perceived physical exertion. Heart rate will be monitored throughout the study, and brain activity may be assessed during cognitive tasks. The study will determine whether acute mental fatigue is associated with changes in muscle strength, limb symmetry, and neuromuscular performance.
Interventions
OTHER
Computer-Based Mental Fatigue Protocol
Participants will complete approximately 30 minutes of standardized computer-based cognitive tasks designed to induce acute mental fatigue. The tasks require sustained attention, concentration, reaction time, working memory, and mental effort and may include the Psychomotor Vigilance Task (PVT), incongruent Stroop task, and n-back task. Participants will complete the mental fatigue protocol after baseline strength testing and before the post-intervention strength assessment. Subjective mental fatigue and sleepiness will be assessed before and after the intervention, and perceived mental effort will be assessed following the intervention.
Primary outcome measures
Lower-Extremity Muscle Strength
Time frame: Baseline and immediately following the approximately 30-minute mental fatigue intervention, during a single study visit lasting up to 2 hours.
Lower-extremity muscle strength will be assessed using a Biodex isokinetic dynamometer during bilateral knee extension and flexion at three different movement speeds. Peak torque will be recorded as the primary measure of muscle strength. Changes in peak torque from baseline to immediately following the computer-based mental fatigue intervention will be evaluated.
Lower-Extremity Limb Symmetry
Time frame: Baseline and immediately following the approximately 30-minute mental fatigue intervention, during a single study visit lasting up to 2 hours.
Limb symmetry will be assessed using peak torque measurements obtained from both lower extremities during isokinetic knee extension and flexion testing. A Limb Symmetry Index (LSI) will be calculated to quantify the similarity in muscle strength between the two lower extremities. Changes in LSI from baseline to immediately following the computer-based mental fatigue intervention will be evaluated.
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- Age 18-39 years
- Able to produce maximal force against Biodex protocol
- Able to perform required lower extremity movements through range of motion necessary for Biodex protocol
- No known cognitive impairment
- Sufficient musculoskeletal health to complete the tasks
Exclusion criteria
- History of a neurological disorder, disease, or cognitive impairment that may affect cognition, motor control, reaction time, or force production
- History of musculoskeletal injury affecting the lower extremities within the past 6 months
- History of lower extremity surgery affecting force production of the hip, knee, or ankle
- Color-vision impairment
- Significant visual or hearing impairment
- History of migraine headaches
- Current significant sleep disturbances or sleep deprivation
- Head injury that may affect cognitive function
- Medical condition affecting ability to produce maximal force safely
- Allergy to adhesive tape, parabens, or propylene glycol
- Scalp lacerations, open wounds, or sutures on the scalp
- Cranial surgery or skull defects
- History of unexplained dizziness or fainting in the past 6 months
- Individuals who are pregnant, prisoners, or not yet adults
- Inability to communicate with investigators
- Inability to provide written informed consent
Where
- Pensacola, Florida
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Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Sep 29, 2026 · Source of record for eligibility and locations