Treadmill training with harness support: selection of parameters for individuals with poststroke hemiparesis.

Locomotor training with a treadmill and harness support is a promising, task-oriented approach to restoring gait function in individuals with poststroke hemiparesis. However, a scientific basis for the proper selection of training parameters is lacking. Considerable latitude exists in the application of locomotor training, and training protocols vary widely between experimenters and clinical settings. Recent studies indicate that the prescription of certain parameters, including body-weight support (BWS) and treadmill speed, can affect treatment outcome in hemiparetic individuals. As an initial step toward developing a basis for selection of parameters, we reviewed the literature for studies that quantified the immediate (i.e., within session) biomechanical effects of adjusting BWS, treadmill speed, support stiffness, and handrail hold during treadmill walking in hemiparetic and nondisabled subjects. We then summarized results from personal investigations of these parameters. Based on the currently available evidence, we discuss the scientific rationale for selecting certain training parameters for individuals with poststroke hemiparesis and outline future directions for research. Key words: biomechanics, body-weight support, cerebrovascular accident, gait, handrail hold, hemiparesis, rehabilitation, speed, support stiffness, treadmill. INTRODUCTION More than three-quarters of a million Americans suffer a first-ever stroke each year, and the survivor cohort now approaches three million persons [1]. Following stroke, many individuals are left with neurological and functional deficits, including hemiparesis, which impair their ability to walk. Approximately two-thirds of acute hospitalized stroke patients cannot walk independently at admission [2]. Of those who recover the ability to walk during acute rehabilitation, many are still handicapped by slow walking speed and limited endurance. These impairments restrict their independent mobility and autonomy and severely impact their quality of life. Locomotor training with a treadmill and harness support is a promising, task-oriented approach to restoring gait function in individuals with poststroke hemiparesis [3-5]. During locomotor training, hemiparetic individuals exhibit a more symmetrical gait [6-8], with more normal kinematics and timing of muscle activity [7]. One or more therapists typically provide manual assistance to guide the trunk and legs through a normal gait trajectory. Improvements in functional locomotor ability, as reflected by increased ambulatory status or overground walking speed, have been demonstrated after locomotor training in individuals in both the subacute and chronic stages of hemiparesis [3-5,9-10]. However, no objective basis currently exists for the proper selection of locomotor training parameters for hemiparetic persons following stroke. Considerable variability exists in the current application of poststroke locomotor training. This variability, along with emerging evidence that the selection of training parameters can affect treatment outcomes [4-5,10], strongly indicates that a scientific basis for the proper selection of locomotor training parameters is overdue. Ultimately, we need to address the entire ensemble of factors that can affect the locomotor training paradigm, including immediate biomechanical effects, key elements of the perceptual environment, cognition, and physiological adaptations to training intensity and duration (heart and respiratory rate, etc.). In this focused review, we summarize the current approaches taken by experimenters in prescribing locomotor training parameters for persons with poststroke hemiparesis. Next, as an initial step toward developing a scientific basis for parameter selection, we reviewed the literature for studies that quantified the immediate (i.e., within session) biomechanical effects of adjusting body-weight support (BWS), speed, support stiffness, and handrail hold during treadmill walking in both hemiparetic and nondisabled subjects. …