VELOCITY-DEPENDENT ONSET OF RECIPROCAL ARM SWING IN NORMAL GAIT: WHEN SHOULD NEUROFACILITATION BEGIN? Roger J. Allen*; Greg A. Harada; Courtney C. Horwath; Jackie M. Murphy Physical Therapy, University of Puget Sound, Tacoma, WA PURPOSE: The purpose of this study was to determine critical gait velocity for normal initiation of neurogenic reciprocal arm swing (RASCV), in an age stratified sample reflective of the age distribution of the CVA patient population in the United States. BACKGROUNDS/SIGNIFICANCE: Numerous neurorehabilitation therapies attempt to facilitate functional movement by assisting the patient in performance of normal movement patterns. Assisted RAS is often utilized in gait retraining, however, the patient may be ambulating below RASCV. Use of passive RAS at low gait velocities may be training an abnormal pattern, counterproductive to facilitation. Based on the results of this investigation, it is recommended that therapists refrain from introducing RAS into neurofacilitative gait rehabilitation until the patient is ambulating at a velocity that is at least the RASCV for his/her age group. SUBJECTS: Seventy-three normal adults, ranging in age from 28 to 74 years, unaffected by restrictions in extremity mobility, or pathology influencing gait mechanics or walking endurance. METHODS AND MATERIALS: Subjects walked uncued on a treadmill at speeds from 0.31 to 1.34 m/s, increasing in 0.04 m/s increments. Motion analysis of reciprocal arm swing (RAS) determined peak flexion/extension excursion of the glenohumeral joint. Excursion of the glenohumeral joint was plotted as a function of gait velocity. ANALYSES: Fourth-order polynomial equations were determined for the line of best fit of the resulting "S" curve for each subject and RASCV was determined by applying a second-derivative test. Critical velocities were determined individually for each subject and grouped into three age epochs. Variables potentially related to RASCV were measured, including customary walking speed, cadence and stride length, true leg and arm length, gender, age, height, and weight. These variables were correlated with RASCV to assess their individual usefulness of possible predictors of RASCV. RESULTS: Findings indicate that a passive RAS, observed primarily at the elbows, begins at approximately 0.40 m/s due to trunk counterrotation in relation to the pelvis. The neurogenic component of RASCV appears to be a function of individual subject factors, showing meaningful correlations with age (r= 0.52) and customary walking speed (r= -0.43). In the 21-44 year old group RASCV was found to average 0.64 m/s, in 45-64 year olds it averaged 0.80 m/s, and in the 65 year old group it averaged 1.03 m/s, with an overall mean for the sample of 0.86 m/s. CONCLUSIONS: These findings reveal that there is a minimum critical gait velocity for neurogenic involvement in normal RAS, which increases with subject age. A 40 year old patient would be ready for RAS introduction when he/she is able to walk a measured 5 meter distance in 7.8 seconds or less, a 50 year old patient in 6.2 seconds, or a 70 year old patient in 4.9 seconds. Therapists are encouraged to use knowledge of critical velocity during normal gait as a guide for determining when to introduce assisted reciprocal arm swing in neurorehabilitation settings. FUNDING SOURCE: University of Puget Sound University Enrichment Committee to fund travel for presentation of findings. KEYWORDS: Critical gait velocity, Reciprocal arm swing, neurofacilitation Copyright 2009 by the American Physical Therapy Association. Requests for reprints should be directed to the corresponding author of the article. Educators, students, and other academic customers may receive permission to reprint copyrighted material from Physical Therapy (ISSN 1538-6724) by contacting the Copyright Clearance Center Inc, 222 Rosewood Dr, Danvers, MA 01923. Other types of customers who want permission to reprint should contact the APTA Editorial Office, Attn: Physical Therapy.