Does the Improvement of Position Sense Following Motor Imagery Practice Vary as a Function of Age and Time of Day?

The effectiveness of motor imagery practice is known to depend on age and on the ability to form motor images. In the same individual, motor imagery quality changes during the day, being better late in the morning for older adults and in the afternoon for younger adults. Does this mean that motor imagery practice should be done at specific time of the day depending on the age of participants to maximize motor learning? To examine whether the effect of motor imagery practice varies as a function of time of day and age, the authors used an arm configuration reproduction task and measured position sense accuracy before and after 135 kinesthetic motor imagery trials. Younger and older participants were randomly assigned to either a morning or an afternoon session. Data showed that the accuracy for reproducing arm configurations improved following imagery practice regardless of time of day for both younger and older adults. Moreover, the authors observed that the position sense was less accurate in the afternoon than in the morning in older participants (before and after motor imagery practice), while performance did not change during the day in younger participants. These results may have practical implications in motor learning and functional rehabilitation programs. They highlight the effectiveness of motor imagery practice for movement accuracy in both younger and older adults regardless of time of day. By contrast, they reveal that the assessment of position sense requires that the time of day be taken into account when practitioners want to report on the older patients' progress without making any mistakes.