Mirror Illusion Training and Cross-education

Not Applicable

• Conditions: Weight Lifting; Exercise Therapy
• Interventions: Other: Unilateral resistance training; Other: Illusionary mirror visual feedback

• Registration Number: NCT05084690
• Lead Sponsor: Texas Christian University

Brief Summary

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.

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 Timeline

• Study Start: 2021-07-19
• Status Verified: 2021-10
• Study First Submitted: 2021-10-07
• Study First Submitted QC: 2021-10-07
• Last Update Submitted: 2021-10-07
• Study First Posted: 2021-10-20
• Last Update Posted: 2021-10-20
• Primary Completion: 2023-08-19
• Study Completion: 2023-08-19

Recruitment & Eligibility

• Status: UNKNOWN
• Sex: All
• Target Recruitment: 20

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 & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Resistance training with mirror illusion group	Illusionary mirror visual feedback	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.
Resistance training control group	Unilateral resistance training	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.
Resistance training with mirror illusion group	Unilateral resistance training	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.

Primary Outcome Measures

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

Trial Locations

Locations (2)

TCU RIC; 🇺🇸 Fort Worth, Texas, United States

TCU Neuromuscular Physiology Laboratory; 🇺🇸 Fort Worth, Texas, United States