Effects of context and instruction on movement kinematics in adults with and without cerebrovascular accident

Successful participation in meaningful tasks and roles following a disabling event involves the interaction between a person's intrinsic strengths and impairments and the environmental context in which the performance of daily activities occurs. A central challenge for the rehabilitation therapist is to identify how contextual constraints influence performance, and to use that knowledge to enhance the effectiveness of intervention.;In Chapter 1, effects of materials-based vs. imagery-based occupation on motor organization were examined in the arm ipsilateral to the site of stroke lesion. Five persons with left CVA and five neurologically-intact participants performed functional tasks (e.g. slicing bread) under four conditions. During the materials-based condition, needed tools and objects were available. In the three imagery-based conditions, either the tool or object of the tool's action was present, or the participant simulated the task without objects. Movement in both groups was significantly faster, more direct, and less forceful during the materials-based condition. Participants appeared to modify their motor actions according to the affordances of the task objects.;Chapter 2 is a review and critique of empirical studies on instruction and motor action in neurologically-intact adults. This qualitative summary was strengthened by quantitative procedures commonly used in meta-analysis. Findings suggest that instruction is a control variable that strongly affects motor performance and learning in neurologically-intact adults. Implications for the therapeutic use of instruction in patients with and without neurological impairments are discussed.;In Chapter 3, a counter-balanced repeated-measures design was used to examine the effects of externally-focused (task related) vs. internally-focused (movement related) instruction on movement kinematics. Participants included sixteen persons with stroke who were able to use their affected arm to perform three functional reaching tasks (e.g. removing a can from a shelf). Movement time was significantly faster and peak velocity greater during the external-focus condition, compared to the internal-focus condition. The clinical implication is that internal-focus instruction can lead to reaching movements that are less efficient (slower) and less forceful in adults with and without CVA. This research reinforces the need for therapists to consider instructions when assessing environmental factors that affect a patient's motor performance.