Influence of Resistance Training Experience and Mental Imagery on Corticospinal Excitability and Inhibition

This study will utilize transcranial magnetic stimulation (TMS) to examine the effects of mental imagery in resistance-trained versus untrained men and women. In randomized order, each participant will perform a mental imagery task or a control condition as TMS is used to study corticospinal excitability.

Kinesthetic mental imagery is a technique that has previously been utilized to modulate neural signaling to the limbs in the absence of any mechanical movement of the limb. Kinesthetic imagery tasks require an individual to imagine they are maximally contracting a target muscle group. Previous investigations have shown mental imagery tasks to increase maximal strength of the limb and even attenuate strength loss during periods of immobilization. Similarly, corticospinal excitability, which indicates the ease in which the cortex can stimulate muscular contraction, has also been shown to increase during mental imagery tasks. These adaptations have been attributed to the role of the cortex as a critical determinant of strength and the potent cortical stimulus posed by mental imagery.

Mental imagery and resistance training have both shown to provide a positive impact on muscle strength. However, the interplay between a mental imagery task and resistance training experience has yet to be fully investigated in terms of their impact on corticospinal excitability and inhibition. To our knowledge, no study has examined the effect of resistance training experience on corticospinal excitability and inhibition during a mental imagery task. Thus, the purpose of this study is to determine if resistance trained and untrained participants experience differences in corticospinal excitability and inhibition during kinesthetic mental imagery.

Eligibility Criteria:
Inclusion Criteria:

* Over the previous six months, participant has performed at least three resistance training sessions per week or
* Over the previous six months, participant has refrained from resistance training entirely.

Exclusion Criteria:

* Do not meet the resistance training experience requirements of either group
* Neuromuscular disease (e.g. Parkinson's, MS, ALS)
* Metabolic disease (e.g. diabetes, thyroid disorder, metabolic syndrome)
* Arthritis in the upper limbs (hands, arms, shoulders)
* Trouble using or controlling one's muscles
* History of cancer
* History of stroke
* History of heart attack
* Use of an assistive walking device or other mobility aids
* Physician mandated contraindication to exercise within the last 6 months
* Epilepsy or history of convulsions/seizures
* History of fainting or syncope
* History of head trauma that was diagnosed as concussion or was associated with loss of consciousness
* History of hearing problems or tinnitus
* Cochlear implants
* Implanted metal in the brain, skull, or elsewhere in the body
* Implanted neurotransmitter
* Cardiac pacemaker or intracardiac lines
* Medication infusion device
* Past problems with brain stimulation
* Past problems with MRI
* Use of muscle relaxants or benzodiazepines
* Allergy to rubbing alcohol
* Any other health related illnesses that would prohibit a participant from physical performance testing
* Lack of transportation to and from the laboratory
* Any permanent / non-removable jewelry or metal fixtures