Estimation of Task Practice Intensity in Individuals with Mild Traumatic Brain Injury

Abstract

<h3>Research Objectives</h3> To investigate the minimal number of repetitions to achieve a plateau (i.e. asymptote) in performance of an UL pointing task in individuals with mild TBI (mTBI). <h3>Design</h3> Cross-sectional study. <h3>Setting</h3> Research Laboratory based in an Academic Institution. <h3>Participants</h3> Ten individuals with mTBI and 7 age-matched controls participated in this study. <h3>Interventions</h3> Both groups of participants were seated. Eight reflective markers were placed at the following Anatomical landmarks, Right and left acromion processes, sternal notch, lateral epicondyle of the elbow, radial styloid process, index finger tip, greater trochanter and on the target. They pointed repeatedly to a target placed in front of them at a distance equal to the length of their upper limb (measured from acromion process to the index fingertip). We aligned the target to their sternal notch and placed it at a height of 90° of shoulder flexion. The trial duration was 3 to 5 seconds and recording frequency was 100 Hz. <h3>Main Outcome Measures</h3> The primary outcome was the number of trials necessary to achieve an asymptote in the endpoint error during pointing movements. The root mean squared error between the endpoint position and the center of the target at the end of the movement quantified the endpoint error. We also quantified movement speed and straightness. The amplitude of the endpoint velocity vector helped calculate movement speed. Movement straightness was quantified using the Index of straightness (IC) based upon the distance covered by the end point. ICs of a straight line and semicircle are 1 and 1.57 respectively. <h3>Results</h3> Individuals with mTBI needed more trials (mean±SD: 32±6.2) to achieve an asymptote compared to healthy controls (16±1.7; p < 0.05). Individuals with mTBI in addition moved slower and had more curved movements compared to healthy controls (p < 0.05). <h3>Conclusions</h3> Information on the number of repetitions can help guide future rehabilitation strategies for individuals with mTBI. <h3>Author(s) Disclosures</h3> This project was funded by a pilot grant from the School of health Professions, UT Health San Antonio. The authors have no other conflicts of interest to declare.