Thesis Defence: The Effect of Motor Imagery Training Ability on Force Steadiness in Old and Young Females

Cori Calkins, supervised by Dr. Jennifer Jakobi, will defend their thesis titled “The Effect of Motor Imagery Training Ability on Force Steadiness in Old and Young Females” in partial fulfillment of the requirements for the degree of Master of Science in Health and Exercise Sciences.

An abstract for Cori Calkins’ thesis is included below.

Defences are open to all members of the campus community as well as the general public. Registration is not required for in person defences.

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ABSTRACT

Motor imagery training (MIT) is the mental rehearsal of a motor task with no overt movement and it increases neural drive. Improvements in force steadiness (FS) are related to adaptations in neural excitability, and in older adults FS is related to performance of functional ability. Age-related decline in functional ability is greater in females compared to males. Purpose: To determine if one session of MIT influences corticospinal excitability and improves FS of isometric elbow flexion contractions in young and old female adults. Hypotheses: MIT would increase corticospinal excitability and improve isometric elbow flexion FS, and the enhancement would be greater in older females compared to younger females Methods: Young (19-35 years old) and old (65-90 years old) participants were randomly assigned to a MIT group or control group that were tested in a similar block fashion. Participants performed isometric elbow flexion contractions at 10% maximal voluntary contraction prior to and following MIT (training group) or no training (control group; viewed documentary for similar time). Elbow flexion contractions were performed in blocks 1,3 and 5. MIT or documentary viewing was performed in blocks 2 and 4. Motor evoked potentials (MEP) elicited by transcranial magnetic stimulation were collected within the last five seconds of each submaximal contraction. Results: 13 old (n=7 MIT) and 22 young participants (n=11 MIT) completed the study. The MIT group had a higher CV of force than the control group in block one (p=0.02), and FS improved in the old group with MIT in block three (p=0.008). There were no significant findings for MEPs (p>0.05). For visual (p=0.05) and global (p=0.04) motor imagery (MI) ratings from the MIT blocks, young had higher MI ratings than old. There was a significant negative relationship in old adults between global (r=-0.715, r2=0.5, p=0.035) and visual (r=-0.773, r2=0.60, p=0.021) MI ratings in the first training block (block 2) and CV of force in the block subsequent to training (block 3), suggesting a higher global and visual MI score was associated with increased ability to produce steady contraction in old adults. Conclusion: Old adults have the ability to undertake MIT and improves FS.