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This Article Full Text Full Text (PDF) All Versions of this Article: 102/5/2856    most recent 00211.2009v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Alibiglou, L. Articles by Brown, D. A. PubMed PubMed Citation Articles by Alibiglou, L. Articles by Brown, D. A.

RESEARCH-ARTICLE

Bilateral Limb Phase Relationship and Its Potential to Alter Muscle Activity Phasing During Locomotion

¹Department of Physical Therapy and Human Movement Sciences, ²Interdepartmental Neuroscience Program (NUIN), and ³Department of Physical Medicine and Rehabilitation, Feinberg School of Medicine, Northwestern University; ⁴Department of Kinesiology and Nutrition, University Of Illinois, Chicago, Illinois; and ⁵Department of Physical Therapy, Governors State University, University Park, Illinois

Submitted 11 March 2009; accepted in final form 3 September 2009

ABSTRACT

It is well established that the sensorimotor state of one limb can influence another limb and therefore bilateral somatosensory inputs make an important contribution to interlimb coordination patterns. However, the relative contribution of interlimb pathways for modifying muscle activation patterns in terms of phasing is less clear. Here we studied adaptation of muscle activity phasing to the relative angular positions of limbs using a split-crank ergometer, where the cranks could be decoupled to allow different spatial angular position relationships. Twenty neurologically healthy individuals performed the specified pedaling tasks at different relative angular positions while surface electromyographic (EMG) signals were recorded bilaterally from eight lower extremity muscles. During each experiment, the relative angular crank positions were altered by increasing or decreasing their difference by randomly ordered increments of 30° over the complete cycle [0° (in phase pedaling); 30, 60, 90, 120, 150, and 180° (standard pedaling); and 210, 240, 270, 300, and 330° out of phase pedaling]. We found that manipulating the relative angular positions of limbs in a pedaling task caused muscle activity phasing changes that were either delayed or advanced, dependent on the relative spatial position of the two cranks and this relationship is well-explained by a sine curve. Further, we observed that the magnitude of phasing changes in biarticular muscles (like rectus femoris) was significantly greater than those of uniarticular muscles (like vastus medialis). These results are important because they provide new evidence that muscle phasing can be systematically influenced by interlimb pathways.