Abstract
Neurophysiological data suggest that a very high number of movement repetitions are required to induce the neuroplastic changes that lead to behavioural improvements in therapy. The volume of repetitions can be thought of as the therapy "dosage". Little is known about the relationship between dosage and magnitude of recovery. We used meta-analytic regression to explore dose-response relationships in physical therapy for adults with stroke. We conducted a systematic review of randomized controlled trials (databases: PubMed, PsychINFO, Google Scholar). 28 RCTs were identified that manipulated time in therapy between treatment and control groups. Meta-regression was used to predict standardized mean differences between treatment and control groups based on additional therapy time and time from stroke onset to treatment. Additional therapy time led to improved treatment outcomes, but this effect was moderated by time post-stroke. In early stages of stroke (0-3 mo.) this effect was attenuated (β = 0.005, se = 0.02). For moderate time post-stroke (3-12 mo.) the strength of this effect increased (β = 0.055, se = 0.02). The effect also increased for longer times post-stroke (>12 mo.; β = 0.039, se = 0.02), but longer times post stroke also had a significant negative effect (β = -0.254, se = 0.18) on the intercept (β = 0.346, se = 0.10). All times post-stroke benefited from additional time in therapy, but additional time had a larger effect after 3 months post-stroke. Theoretical implications of these data are discussed as are important suggestions for future research.
