How Many Minutes of Imagery per Day Is an Optimal Dose?
Researchers from the University of Cincinnati Academic Medical Center evaluated and compared the efficacy of 20-, 40-, and 60-minute mental practice (guided imagery) sessions on affected upper extremity impairment and functional limitation, using a randomized, controlled study with a multiple baseline design.
Twenty-nine subjects with chronic stroke, exhibiting stable, mild hemiparesis (weakness on one side), were given 30-minute rehabilitative sessions, 3 days/week for 10 weeks, emphasizing affected upper extremity use during valued activities.
Directly after these sessions, randomly selected subjects were given audiotaped mental practice for 20, 40, or 60 minutes. Subjects assigned to a control group received the same therapy as the mental practice groups, and an audiotaped sham intervention directly after therapy sessions.
Main outcome measures were assessed by the Fugl-Meyer (FM) motor assessment and the Action Research Arm Test (ARAT).
No pre-existing differences were found between groups on any demographic variable or movement scale. On the FM, mental practice duration significantly predicted positive change (P = 0.05), with increasing duration related to larger FM score increases (5.4 point score increase for the 60-minute duration group). On the ARAT, a non-significant trend was seen (P = 0.78), favoring the 20-minute dosing condition (4.5 point increase).
Importantly, regardless of dosing condition, subjects who used mental practice exhibited markedly larger score changes on both the FM and ARAT than subjects not receiving mental practice.
The investigators conclude that 60 minutes of mental practice appears to most significantly reduce affected arm impairment. However, with functional limitation, there was a trend favoring the shortest (20 minutes) duration. Results suggest that a stroke rehabilitative regimen augmented by mental practice renders a greater functional impact than therapy only.
Citation: Page SJ, Dunning K, Hermann V, Leonard A, Levine P. Longer versus shorter mental practice sessions for affected upper extremity movement after stroke: a randomized controlled trial. Clinical Rehabilitation. 2011 Jul;25(7):627-37. Epub 2011 Mar 22. [email protected]