Nonlinear mixed-effects model reveals a distinction between learning and performance in intensive reach training post-stroke

Background: we recently showed that individuals with chronic stroke who completed two sessions of intensive unassisted arm reach training exhibited improvements in movement times up to one month post-training. here,we study whether changes in movement times during training can predict long-term changes. methods: sixteen participants with chronic stroke and ten non-disabled age-matched participants performed two sessions of reach training with 600 movements per session. movement time data during training were fitted to a nonlinear mixed-effects model consisting of a decreasing exponential term to model improvements of performance due to learning and an increasing linear term to model worsening of performance due to activity-dependent fatigability and/or other factors unrelated to learning. results: for non-disabled age-matched participants,movement times gradually decreased overall during training and overall changes in movement times during training predicted long-term changes. in contrast,for participants post-stroke,movement times often worsened near the end of training. as a result,overall changes in movement times during training did not predict long-term changes in movement times in the stroke group. however,improvements in movement times due to training,as estimated by the exponential term of the model,predicted long-term changes in movement times. conclusion: participants post-stroke showed a distinction between learning and performance in unassisted intensive arm reach training. despite worsening of performance in later trials,extended training was beneficial for long-term gains. © 2017 the author(s).