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.
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
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
SINGLE
Enrollment
20
Unilateral resistance training of the elbow flexors
Modified Ramachandran's mirror box
TCU Neuromuscular Physiology Laboratory
Fort Worth, Texas, United States
TCU RIC
Fort Worth, Texas, United States
Change in dynamic muscle strength for the trained and untrained arm
Dynamic 1-repetition maximum (lbs)
Time frame: Baseline (week 0) post-training (week 5)
Change in isometric muscle strength for the trained and untrained arm
Isometric maximal voluntary contraction
Time frame: Baseline (week 0) post-training (week 5)
Change in lean mass for the trained and untrained arm
DEXA (g)
Time frame: 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)
Time frame: Baseline (week 0), mid-training (week 2), post-training (week 5)
Change in muscle activation for the trained and untrained arm
Electromyographic amplitude (volts)
Time frame: Baseline (week 0) post-training (week 5)
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