Short-Duration and Intensive Training Improves Long-Term Reaching Performance in Individuals With Chronic Stroke

Abstract

Previous studies have shown that multiple sessions of reach training lead to long-term improvements in movement time and smoothness in individuals post-stroke. Yet such long-term training regimens are often difficult to implement in actual clinical settings. In this study, we evaluated the long-term and generalization effects of short-duration and intensive reach training in 16 individuals with chronic stroke and mild to moderate impairments. Participants performed 2 sessions of unassisted intensive reach training, with 600 movements per session, and with display of performance-based feedback after each movement. The participants' trunks were restrained with a belt to avoid compensatory movements. Training resulted in significant and durable (1 month) improvements in movement time (20.4% on average) and movement smoothness (22.7% on average). The largest improvements occurred in individuals with the largest initial motor impairments. In addition, training induced generalization to nontrained targets, which persisted in 1-day and in 1-month retention tests. Finally, there was a significant improvement in the Box and Block test from baseline to 1-month retention test (23% on average). Thus, short-duration and intensive reach training can lead to generalized and durable benefits in individuals with chronic stroke and mild to moderate impairments.

Keywords: arm movements; generalization; long-term retention; reach training; stroke rehabilitation.

Conflict of interest statement

Declaration of Conflicting Interests

The authors declared no conflicts of interest with respect to the authorship and/or publication of this article.

© The Author(s) 2015.

Figures

Figure 1

Experimental design and the Arm Reach Training (ART) system. A: Diagram showing the timing of the five visits over a 6-week period for the stroke group. B: Left: ART system: the home-position is identified by the green circle and a target by the white circle. For each trial, participants were instructed to reach to the target with their index fingertip (of more affected hand in stroke group and dominant hand in control group) as quickly as possible. Right: Diagram showing the location of the 35 test targets in the two dimensional workspace. The five targets at 25 cm (black circles) are the training targets. C: Illustration of the five possible types of visuo-auditory feedback cues at the end of a training trial based on comparison of MTon-line to the mean and standard deviation of the movement time (mean MTon-line and std) computed in 20 previous trials (except for the first block: see method).

Figure 2

Examples of hand paths and tangential hand velocities before and after training for two subjects post-stroke (Subject 10 and Subject 5 from Table 1) in Pre1-test and in 1-day and 1-month retention tests. First row: Hand path. Second row: Tangential velocities and number of peaks (indicated with filled symbols: circle for Pre1-test, diamond for 1-day retention test, and square for 1-month retention test). Notice how the subject 10 on the left, with relatively high severity score (FM = 30/66), shows a large decrease in movement time and number of peaks compared with the subject 5 on the right with a lesser severity score (FM = 51/66).

Figure 3

A: Mean movement time in the stroke group across the test sessions. B: Mean movement time in the control group. C: Overall movement time before, during, and after training in the stroke group shows a significant and long-lasting (1 month) reduction of MT following training. D: Regression coefficient of target distance (Test × D) in each test in the mixed regression model shows a long-lasting reduction of the effect of distance on MT in the stroke group. E: Regression coefficient of target angle (Test × cos(150-q)) in each test in the mixed regression model shows a long-lasting reduction in the effect of angle on MT in the stroke group. * p

Figure 4

A: Mean number of peak in the stroke group across test sessions (results for the control group are not shown because the mean number of peaks is very close to one for all movements). B: Overall number of peaks before, during, and after training shows a significant and long-lasting (1 month) reduction in the number of peaks following training. C: Regression coefficient of target distance (Test × D) in each test in the mixed regression model shows a long-lasting reduction of the effect of distance on number of peak in the stroke group. D: Regression coefficient of target angle (Test × cos(150-q)) in each test in the mixed regression model shows a long-lasting reduction in the effect of angle on number of peak in the stroke group. ** p

Figure 5

Relationship between initial performance and change in performance between Pre1-test and 1-day retention test in stroke group. A: Linear relationship was significant between initial MT and ΔMT. B: Linear relationship was significant between initial number of peaks and Δpeaks.