Effect of motor imagery on the neurological activation of the immobilized soleus muscle

Injuries to the lower leg occur often in the physically active population and immobilization of a short time is used as part of the treatment protocol. However, immobilization has been found to alter the neurological system of the lower extremity. This study seeks to investigate whether the use of motor imagery can attenuate any detrimental effects of immobilization. Participants were healthy with a moderate physical activity level as well as moderate imagery ability. Fifteen individuals were divided into two groups: an imagery (4 males, 3 females) and control group (6 males, 2 females). All participants were immobilized in a walking boot for 5 days and the H-reflex was measured. The imagery group underwent imagery training three times a day whereas the control group received no intervention. A 2 x 3 RM-ANOVA was used to investigate the effect of motor imagery on motoneuron pool excitability during immobilization. The H-reflex was the dependent variable and time (baseline, day 3 and day 5) and group (imagery, control) the independent variables with significance set at 0.05. No significant interaction was found, suggesting no change in motoneuron pool excitability with the use of imagery compared to the control group. Therefore, the use of imagery had no influence on the neurological activity of the lower leg as measured by the H-Reflex in this study. The absence of a time effect indicated that immobilization did not have the expected effect on the H-reflex. Participant responses were highly variable and several measurement issues may have affected the results. A majority of the imagery were able to stabilize their H-reflex with imagery over 5 days. The results of this study enhance understanding of the neurological mechanisms and changes occurring during immobilization and the role motor imagery plays. Furthermore, this study serves as a base to build upon for future research.