Head movement kinematics during rapid aiming task performance in healthy and neck-pain participants: the importance of optimal task difficulty.

BACKGROUND: Head repositioning tasks have been used in different experimental and clinical contexts but have yet to offer insight as to the task performance strategy. The purpose of this study was to explore the kinematics from a head aiming task that encompasses a Fitts' task in neck pain patients and healthy control subjects.
METHODS: Chronic neck pain patients and healthy individuals were compared in a head aiming task. Participants were asked to move their head as quickly, and precisely as possible to a target under 4 different experimental conditions. Dependent variables included movement time, movement time variability, acceleration phase duration, deceleration phase duration and absolute positioning error.
RESULTS: The chronic neck pain patients, when compared to healthy participants showed a significant increase in movement time and deceleration phase duration for the small target/large movement amplitude condition. No group difference was observed for movement time variability, acceleration phase duration and absolute positioning errors.
CONCLUSIONS: Decreased motor performance was observed in chronic neck pain patients during the most challenging cervical pointing task condition. These results may imply that in order for a performance based outcome measure to yield observable differences conditions that meet or exceed the optimum challenge point of the population tested should be employed. Copyright 2010 Elsevier Ltd. All rights reserved.