Faster treadmill walking facilitates a more normal walking pattern after stroke, without concomitant increases in common gait compensations, such as circumduction. The improvements in gait deviations were observed with small increases in walking speed.

Tyrell CM, Helm E, Reisman DS. Learning the spatial features of a locomotor task is slowed after stroke. J Neurophysiol 112: 480 -489, 2014. First published April 30, 2014 doi:10.1152/jn.00486.2013The capacity for humans to learn a new walking pattern has been explored with a split-belt treadmill during single sessions of adaptation, but the split-belt treadmill can also be used to study longer-term motor learning. Although the literature provides some information about motor learning after stroke, existing studies have primarily involved the upper extremity and the results are mixed. The purpose of this study was to characterize learning of a novel locomotor task in stroke survivors. We hypothesized that the presence of neurological dysfunction from stroke would result in slower learning of a locomotor task and decreased retention of what was learned and that these deficits would be related to level of sensorimotor impairment. Sixteen participants with stroke and sixteen neurologically intact participants walked on a split-belt treadmill for 15 min on 5 consecutive days and during a retention test.Step length and limb phase were measured to capture learning of the spatial and temporal aspects of walking. Learning the spatial pattern of split-belt treadmill walking was slowed after stroke compared with neurologically intact subjects, whereas there were no differences between these two groups in learning the temporal pattern. During the retention test, poststroke participants demonstrated equal retention of the split-belt treadmill walking pattern compared with those who were neurologically intact. The results suggest that although stroke survivors are slower to learn a new spatial pattern of gait, if given sufficient time they are able to do so to the same extent as those who are neurologically intact. stroke; locomotion; learning; adaptation MOTOR LEARNING is traditionally defined as a persistent change in a movement that occurs over long-term practice and experience and that results in stable performance (Schmidt 1988;Schmidt and Wrisberg 2000). The process of learning begins with exposure to the task, followed by consolidation, which is a set of processes that involve changes in the central nervous system leading to a long-term memory that is resistant to disruption or interference by other motor activity (Krakauer and Shadmehr 2006;Stickgold and Walker 2007). These processes ultimately lead to the ability to recall the newly learned motor skill in the appropriate context or environment.The capacity for humans to learn a new walking pattern has been explored with a split-belt treadmill (Malone et al. 2011) and a rotating treadmill (Earhart et al. 2001). During walking on a rotating treadmill, subjects adapt their walking pattern while walking in place on the perimeter of a rotating disk. After ϳ30 min of exposure, when the subjects are blindfolded and asked to walk under normal conditions they demonstrate an involuntary and significant curvature of their walking trajectory. The split-belt treadmill is a trea...

Independently, aging and stroke each have a significant negative impact on skeletal muscle, but the potential cumulative effects of aging and stroke have not been explored. Optimal interventions for individuals post-stroke may include those that specifically target skeletal muscle. Addressing changes in muscles may minimize activity limitations and enhance participation post-stroke. This paper reviews the impact of aging and stroke on muscle morphology and composition, including fiber atrophy, reductions in muscle cross-sectional area, changes in muscle fiber distributions, and increases in intramuscular fat. Relationships between changes in muscle structure, muscle function, and physical mobility are reviewed. Clinical recommendations that preserve and enhance skeletal muscle in the aging adult and individuals post-stroke are discussed. Future research directions that include systematic comparison of the differences in skeletal muscle between younger and older adults who have sustained a stroke are suggested.

Stroke survivors without cerebellar involvement retain the ability to adapt to the split-belt treadmill, however it has been suggested that their rate of adaptation may be slowed compared to those who are neurologically intact. Depending on limb placement, the split-belt treadmill can be configured to either exaggerate baseline asymmetry, or reduce it, which may affect the behavior of adaptation or de-adaptation. The objectives of this study were to characterize the rate and magnitude of locomotor (de)adaptation in chronic stroke survivors compared to healthy matched subjects, and to evaluate whether exaggeration or reduction of baseline asymmetry impact the responses. Seventeen stroke survivors and healthy subjects completed 10 minutes of split-belt treadmill walking, then 5 minutes of tied-belt walking. Stroke survivors completed this once with each leg on the fast belt. Magnitude and rate of (de)adaptation were evaluated for step length and limb phase asymmetry. There were no differences between the groups with the exception of the reduced step length asymmetry configuration, in which case there was a significantly reduced magnitude (p=<0.000) and rate (p=0.011) of adaptation when compared to controls. There was a similar trend observed during post-adaptation for the exaggerated asymmetry group. The rate and magnitude of locomotor (de)adaptation is similar between chronic stroke survivors and neurologically intact controls, except when the adaptation or de-adaptation response would take the stroke survivors away from a symmetric step length pattern. This suggests that there may be some benefit to symmetry that is recognized by the system.

Induction of neural plasticity through motor learning has been demonstrated in animals and humans. Brain derived neurotrophic factor (BDNF), a member of the neurotrophin family of growth factors, is thought to play an integral role in modulation of central nervous system plasticity during learning and motor skill recovery. Thirty percent of humans possess a single nucleotide polymorphism on the BDNF gene (Val66Met), which has been linked to decreased activity dependent release of BDNF. Presence of the polymorphism has been associated with altered cortical activation, short term plasticity and altered skill acquisition, and learning in healthy humans. The impact of the Val66Met polymorphism on motor learning post-stroke has not been explored. The purpose of this study was to examine the impact of the Val66Met polymorphism in learning of a novel locomotor task in subjects with chronic stroke. It was hypothesized that subjects with the polymorphism would have an altered rate and magnitude of adaptation to a novel locomotor walking paradigm (the split-belt treadmill), compared to those without the polymorphism. The rate of adaptation was evaluated as the reduction in gait asymmetry during the first 30 (early adaptation) and last 100 (late adaptation) strides. Twenty-seven individuals with chronic stroke participated in a single session of split-belt treadmill walking and tested for the polymorphism. Step length and limb phase were measured to assess adaptation of spatial and temporal parameters of walking. The rate of adaptation of step length asymmetry differed significantly between those with and without the polymorphism, while the amount of total adaptation did not. These results suggest that chronic stroke survivors, regardless of presence or absence of the polymorphism, are able to adapt their walking pattern over a period of trial and error practice, however the presence of the polymorphism influences the rate at which this is achieved.