Aerobic exercise improves cognition and motor function poststroke

Abstract

Background: Cognitive deficits impede stroke recovery. Aerobic exercise (AEX) improves cognitive executive function (EF) processes in healthy individuals, although the learning benefits after stroke are unknown.

Objective: To understand AEX-induced improvements in EF, motor learning, and mobility poststroke.

Methods: Following cardiorespiratory testing, 38 chronic stroke survivors were randomized to 2 different groups that exercised 3 times a week (45-minute sessions) for 8 weeks. The AEX group (n = 19; 9 women; 10 men; 64.10 +/- 12.30 years) performed progressive resistive stationary bicycle training at 70% maximal heart rate, whereas the Stretching Exercise (SE) group (n = 19; 12 women; 7 men; 58.96 +/- 14.68 years) performed stretches at home. Between-group comparisons were performed on the change in performance at "Post" and "Retention" (8 weeks later) for neuropsychological and motor function measures.

Results: VO(2)max significantly improved at Post with AEX (P = .04). AEX also improved motor learning in the less-affected hand, with large effect sizes (Cohen's d calculation). Specifically, AEX significantly improved information processing speed on the serial reaction time task (SRTT; ie, "procedural motor learning") compared with the SE group at Post (P = .024), but not at Retention. Also, at Post (P = .038), AEX significantly improved predictive force accuracy for a precision grip task requiring attention and conditional motor learning of visual cues. Ambulation and sit-to-stand transfers were significantly faster in the AEX group at Post (P = .038), with balance control significantly improved at Retention (P = .041). EF measurements were not significantly different for the AEX group.

Conclusion: AEX improved mobility and selected cognitive domains related to motor learning, which enhances sensorimotor control after stroke.

Figure 1. Change in Serial Reaction Timed Task (SRRT) Performance Between Groups

Note: Using a blocked design, the colored circles appeared one at a time in either a randomized or repeated sequence. Once the colored circle appeared on the computer screen, participants were instructed to press the corresponding key as fast as possible (see inset). To index learning, the change in the mean response time was calculated for the random and also repeated sequences. Compared with the stretching exercise (SE) group, the aerobic exercise (AEX) group made significantly more change in the response time (ie, were faster; P = .024) at “Post” for the repeated sequence (sequence-specific learning) but not for the random sequence (nonspecific learning).

Figure 2. Change in Grip Force Accuracy (Predictive Grip Force Modulation [PGFM]) Between Groups

Note: The novel test object (top panel) has two 6-axis force plates that measure the horizontal grip force (GF), vertical lift force (LF), and anterior–posterior shear force (SF) applied to the object during precision grip. Prior to each lift, participants observed a colored weight (see inset) that was randomly inserted into the novel test object by the experimenter. Thus, the visual color cue indicated the weight of the object for the subsequent lift. Generating low predictive grip forces (prior to somatosensory feedback) to lift the object with the 500-g weight suggest that individuals learned the color–weight relationship. At “Post,” the aerobic exercise (AEX) group significantly decreased (P < .038) their predicted mean grip forces (measured at lift-off of the object) when lifting the object (500-g weight) compared with the stretching exercise (SE) group.