Acute Mental Fatigue and Muscle Strength

NCT07846618 | Recruiting

• 1 other identifier: IRB-2026-0026
• Study Type: interventional
• Target: 50
• Locations: 1 country
• Sites: 1

Brief Summary

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.

Conditions

Mental Fatigue; Muscle Strength Dynamometer

Keywords

mental fatigue; muscle strength; limb symmetry; isokinetic dynamometry; electromyography

Outcome Measures

Primary Outcomes (2)

• Lower-Extremity Muscle Strength

  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.

  Baseline and immediately following the approximately 30-minute mental fatigue intervention, during a single study visit lasting up to 2 hours.

• Lower-Extremity Limb Symmetry

  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.

  Baseline and immediately following the approximately 30-minute mental fatigue intervention, during a single study visit lasting up to 2 hours.

Study Arms (1)

Mental Fatigue Intervention

EXPERIMENTAL

Participants will complete baseline lower-extremity muscle strength testing followed by approximately 30 minutes of standardized computer-based cognitive tasks designed to induce acute mental fatigue. Lower-extremity muscle strength testing will then be repeated immediately following the mental fatigue intervention.

Other: Computer-Based Mental Fatigue Protocol

Interventions

Computer-Based Mental Fatigue Protocol OTHER

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.

Mental Fatigue Intervention

Eligibility Criteria

• Age: 18 Years - 39 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• 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

You may not qualify if:

• 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

Sponsors & Collaborators

• Florida Institute for Human and Machine Cognition: lead

Study Sites (1)

Florida Institute for Human and Machine Cognition

Pensacola, Florida, 32502, United States

RECRUITING

MeSH Terms

Conditions

Mental Fatigue

Condition Hierarchy (Ancestors)

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

Study Officials

• Nicole K Rendos, PhD

  Florida Institute for Human and Machine Cognition

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Nicole K Rendos, PhD

CONTACT

850-202-4442; nrendos@ihmc.org

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NA
• Masking: NONE
• Purpose: BASIC SCIENCE
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Research Scientist

Model Details: Single Group, within-subject, pre-post repeated-measures study

Study Record Dates

• First Submitted: September 23, 2026
• First Posted: September 29, 2026
• Study Start: September 23, 2026
• Primary Completion (Estimated): December 31, 2027
• Study Completion (Estimated): December 31, 2027
• Last Updated: September 29, 2026

Record last verified: 2026-09

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL
• Time Frame: Data will be available beginning 12 months and ending 36 months following publication of the primary findings from this study.
• Access Criteria: De-identified data may be shared with scientific and clinical researchers for research purposes, including individual participant data meta-analyses. Requests for data should be directed to Dr. Nicole Rendos at nrendos@ihmc.org and may be submitted up to 36 months following publication of the primary findings from this study. Researchers requesting access will be required to provide an appropriate scientific rationale for the request and sign a data access agreement before receiving the data.

Locations

US (1)