Hi Ilker

Colleagues of mine (Dr's Brook Galna and Lisa Alcock) have examined obstacle crossed and foot clearance with 3D motion analysis and GaitRite - you might want to send them a private message for their guidance. Specifically they might be helpful with regards gait characteristics as (proxy) measures for postural control, e.g. step width and step width variability, which stem from a conceptual model of gait that we use consistently within our work.

Cheers

Alan

Ilker,

I believe you are asking whether APAs are present during more functional locomotor activities. Compared to unobstructed, overground locomotion, we know that the individuals alter a variety of gait parameters and the trajectory of the swing limb as they approach the obstacle (see some of the work from Shirley Rietdyk, Aftab Patla, and others). Changes to posture necessarily occur prior to the transition from dual to single limb stance and serve to maintain the center-of-gravity within the base-of-support of the stance limb and rotate the body over the stance ankle to maintain forward momentum. If APAs are considered compensatory muscle activity (e.g., co-contraction) or limb movement occurring prior to the execution of a focal or goal-directed behavior, then I would presume that you would observe altered muscle activation patterns of the limbs and/or axial segments in the steps preceding and following the obstacle. In order to get at your question, you could perhaps compare the kinematic, kinetic, and electromyographic variables (whichever ones suit your question) during unobstructed and obstructed walking to examine movement alterations that occur in response to this environmental challenge. However, in my opinion, dichotomous perspectives of motor control that treat "postural" and "goal-directed" movements as fundamentally different are unnecessary. Movement dynamics are consistently altered with respect to environmental manipulations in a manner that supports the completion of higher order behavioral goals.

Best of luck with your work!

Josh

Interesting subject.

Perhaps APA and CPA's can be used to train the CNS to be more adaptable and/or responsive to retraining and biofeedback after injury and/or biomedical engineering of the lower extremity?

Dennis

Here some interesting article about APA.