Does Unilateral Pedaling Activate a Rhythmic Locomotor Pattern in the Nonpedaling Leg in Post-Stroke Hemiparesis?

• Published in: Journal of neurophysiology Vol. 95; no. 5; pp. 3154 - 3163
• Main Authors: Kautz, S. A, Patten, C, Neptune, R. R
• Format: Journal Article
• Language: English
• Published: United States Am Phys Soc 01-05-2006
• Subjects: Aged; Electromyography - methods; Female; Functional Laterality - physiology; Humans; Leg - innervation; Leg - physiopathology; Male; Middle Aged; Movement - physiology; Muscle, Skeletal - physiopathology; Paresis - etiology; Paresis - physiopathology; Periodicity; Stroke - complications; Walking - physiology
• ISSN: 0022-3077; 1522-1598
• DOI: 10.1152/jn.00951.2005

1 Brain Rehabilitation Research Center, Malcom Randall Veterans Affairs Medical Center, Gainesville, Florida; 2 Department of Physical Therapy and 3 Brooks Center for Rehabilitation Studies, University of Florida, Gainesville, Florida; 4 Rehabilitation Research and Development Center, Veterans Affairs Palo Alto Health Care System, Palo Alto, California; 5 Department of Orthopaedic Surgery, Stanford University School of Medicine, Stanford, California; and 6 Department of Mechanical Engineering, University of Texas, Austin, Texas
Submitted 8 September 2005;
accepted in final form 25 January 2006
Recent investigation in persons with clinically complete spinal cord injury has revealed that locomotor activity in one limb can activate rhythmic locomotor activity in the opposite limb. Although our previous research has demonstrated profound influences of the nonparetic limb on paretic limb motor activity poststroke, the potency of interlimb pathways for increasing recruitment of the paretic limb motor pattern is unknown. This experiment tested whether there is an increased propensity for rhythmic motor activity in one limb (pedaling limb) to induce rhythmic motor activity in the opposite limb (test limb) in persons poststroke. Forty-nine subjects with chronic poststroke hemiparesis and twenty controls pedaled against a constant mechanical load with their pedaling leg while we recorded EMG and pedal forces from the test leg. For the experimental conditions, subjects were instructed to either pedal with their test leg (bilateral pedaling) or rest their test leg while it was either stationary or moved anti-phased (unilateral pedaling). In persons poststroke, unilateral pedaling activated a complete pattern of rhythmic alternating muscle activity in the nonpedaling, test leg. This effect was most clearly demonstrated in the most severely impaired individuals. In most of the control subjects, unilateral pedaling activated some muscles in the nonpedaling leg weakly, if at all. We propose that, ipsilateral excitatory pathways associated with contralateral pedaling in control subjects are increasingly up-regulated in both legs in persons with hemiparesis as a function of increased hemiparetic severity. This enhancement of interlimb pathways may be of functional importance since contralateral pedaling induced a complete motor pattern of similar amplitude to the bilateral pattern in both the paretic and nonparetic leg of the subjects with severe hemiparesis.
Address for reprint requests and other correspondence: S. A. Kautz, Brain Rehabilitation Research Center, Malcom Randall VA Medical Center (151A), 1601 SW Archer Rd., Gainesville, FL 32608-1197 (E-mail: skautz{at}phhp.ufl.edu )