Interlimb Influences on Paretic Leg Function in Poststroke Hemiparesis

• Published in: Journal of neurophysiology Vol. 93; no. 5; pp. 2460 - 2473
• Main Authors: Kautz, S. A, Patten, C
• Format: Journal Article
• Language: English
• Published: United States Am Phys Soc 01-05-2005
• Subjects: Aged; Aged, 80 and over; Bicycling - physiology; Biomechanical Phenomena; Electromyography - methods; Female; Functional Laterality - physiology; Humans; Isometric Contraction - physiology; Leg - physiology; Male; Middle Aged; Motor Skills; Movement; Muscle, Skeletal - innervation; Muscle, Skeletal - physiopathology; Paresis - physiopathology; Stroke - physiopathology; Task Performance and Analysis
• ISSN: 0022-3077; 1522-1598
• DOI: 10.1152/jn.00963.2004

1 Brain Rehabilitation Research Center, Malcom Randall Veterans Affairs Medical Center, Gainesville, Florida; 2 Rehabilitation Research and Development Center, Veterans Affairs Palo Alto Health Care System, Palo Alto, California; 3 Department of Physical Therapy and 4 Brooks Center for Rehabilitation Studies, University of Florida, Gainesville, Florida; and 5 Department of Orthopaedic Surgery, Stanford University Medical School, Stanford, California
Submitted 15 September 2004;
accepted in final form 3 December 2004
After stroke, paretic leg motor impairment is typically viewed as a unilateral control deficit. However, much of the neural circuitry controlling normal leg function is organized bilaterally to produce coordinated, task-specific activity in the two legs. Thus, as a result of contralesional neural control processes, paretic leg motor pattern generation may be substantially influenced by the nonparetic leg sensorimotor state during bilateral lower limb tasks. Accordingly, we investigated whether different paretic leg motor patterns are observed during mechanically equivalent bilateral and unilateral tasks and, if so, whether nonparetic leg participation improved or exacerbated paretic leg coordination deficits. A pedaling apparatus that mechanically decoupled the legs was used to present subjects with increasingly complex bi- and unilateral motor tasks: isometric force generation, discrete movement, and pedaling. Bilateral electromyographic and pedal force data were collected from 21 persons with chronic poststroke hemiparesis and 11 similarly aged controls. During isometric force generation and discrete movements, nonparetic leg influences on paretic leg coordination were similar and not markedly different from interlimb influences in controls. In bilateral pedaling, however, interlimb influences differed from controls such that paretic leg coordination deficits were exacerbated. During pedaling movements, the suppression of interlimb influences similar to those observed in isometric and discrete movement may occur in controls but may be disrupted in hemiparesis. We suggest that the coupling of pattern generation between the two legs may result in greater, albeit more impaired, paretic leg motor output during bilateral pedaling than during unilateral pedaling.
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 )