Mirror Illusion Training and Cross-education

Mirror Illusion Training to Improve Contralateral Arm Strength

Cross-education describes the transfer of motor performance to the opposite limb following unilateral training and is primarily explained by adaptations within the brain. The mirror training hypothesis suggests that illusionary mirror visual feedback may augment the cross-education of strength to the untrained, contralateral limb. The purpose of this project is to examine how the use of illusionary mirror visual feedback shapes the neuromuscular adaptations that occur for both limbs during unilateral (single-limb) strength training. Our hypothesis is that mirror training will augment the level of cross-education for the untrained arm.

Study Overview

• Status: Enrolling by invitation
• Conditions: Exercise Therapy; Weight Lifting
• Intervention / Treatment: Other: Unilateral resistance training; Other: Illusionary mirror visual feedback

Detailed Description

Recent empirical evidence shows a heightened level of strength transfer with the use of illusionary mirror visual feedback, but this was shown for the small muscles of the wrist during isokinetic training. It is unknown if larger, multi-joint muscles respond favorably to mirror training in practical settings. A randomized controlled study design will allocate approximately 20 participants into two groups. One group will perform unilateral strength training with illusionary mirror visual feedback (Mirror) and the other will perform the same unilateral strength training but without a mirror (No-Mirror). The intervention will involve four weeks of unilateral strength training performed twice weekly at high intensities (>80%1RM).

• Study Type: Interventional
• Enrollment (Anticipated): 20
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Texas
    • Fort Worth, Texas, United States, 76126
      • TCU Neuromuscular Physiology Laboratory
    • Fort Worth, Texas, United States, 76126
      • TCU RIC

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 35 years (Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• right-hand dominance
• no previous strength training of upper body last 3 months
• no injuries or recent surgeries of the upper limbs
• willingness to adhere to the strength training requirements of the study

Exclusion Criteria:

• current use of hormone replacement therapy
• pregnancy/breastfeeding

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Resistance training control group; The resistance training control group will perform unilateral resistance training on their dominant arm. The training will be performed twice per week for four weeks totaling eight training sessions.	Other: Unilateral resistance training; Unilateral resistance training of the elbow flexors
Experimental: Resistance training with mirror illusion group; The resistance training with mirror illusion group will perform unilateral resistance training on their dominant arm. During training, they will view a mirror illusion of their exercising arm over their opposite, non-exercising arm. The training will be performed twice per week for four weeks totaling eight training sessions.	Other: Unilateral resistance training; Unilateral resistance training of the elbow flexors; Other: Illusionary mirror visual feedback; Modified Ramachandran's mirror box

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in dynamic muscle strength for the trained and untrained arm	Dynamic 1-repetition maximum (lbs)	Baseline (week 0) post-training (week 5)
Change in isometric muscle strength for the trained and untrained arm	Isometric maximal voluntary contraction	Baseline (week 0) post-training (week 5)
Change in lean mass for the trained and untrained arm	DEXA (g)	Baseline (week 0), mid-training (week 2), post-training (week 5)
Change in muscle thickness for the trained and untrained arm	Ultrasound muscle thickness (cm)	Baseline (week 0), mid-training (week 2), post-training (week 5)
Change in muscle activation for the trained and untrained arm	Electromyographic amplitude (volts)	Baseline (week 0) post-training (week 5)

Collaborators and Investigators

• Sponsor: Texas Christian University
• Investigators: Principal Investigator: Joshua C Carr, Texas Christian University

Study record dates

Study Major Dates

• Study Start (Actual): July 19, 2021
• Primary Completion (Anticipated): August 19, 2023
• Study Completion (Anticipated): August 19, 2023

Study Registration Dates

• First Submitted: October 7, 2021
• First Submitted That Met QC Criteria: October 7, 2021
• First Posted (Actual): October 20, 2021

Study Record Updates

• Last Update Posted (Actual): October 20, 2021
• Last Update Submitted That Met QC Criteria: October 7, 2021
• Last Verified: October 1, 2021

More Information

Terms related to this study

• Keywords: Strength training; Mirror visual feedback
• Additional Relevant MeSH Terms: Nervous System Diseases; Neurologic Manifestations; Neurobehavioral Manifestations; Perceptual Disorders; Illusions
• Other Study ID Numbers: 2021-102

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No