EFFECTS OF CARRYING BACKPACKS ON GAIT VELOCITY IN CHILDREN WITH JUVENILE ARTHRITIS. Doreen M. Stiskal*1; Jeannette Elliott1; Elizabeth C. Chalom2 1. Graduate Programs in Health Sciences, Seton Hall University, South Orange, NJ; 2. Pediatric Rheumatology, St. Barnabas Health Care System, Livingston, NJ PURPOSE: Over 40 million students in the United States carry school backpacks. While the effects of load carrying and walking has been investigated in healthy children, no known studies appear concerning load carrying in children with movement disorders such as juvenile arthritis (JA). The purpose of this pilot study was to investigate the changes in gait velocity of school-aged children with JA while carrying a loaded backpack. BACKGROUNDS/SIGNIFICANCE: Understanding the influences that loaded backpacks have on gait parameters will enable physical therapists and physicians to help students with JA and their parents make better decisions about modifying this common activity of daily living. SUBJECTS: Twelve subjects (mean age: 12.6 years, range: 9 to 17 years; mean weight: 119.7 pounds, range: 64 to 242 pounds) diagnosed with JA affecting one or more joints in either lower extremity participated in the study. METHODS AND MATERIALS: Subjects ambulated with a standard backpack under six testing conditions that varied load (empty, 7.5 lbs, 15 lbs) and carrying conditions (two shoulder straps, one shoulder strap on the right). Each subject began and ended by walking with the backpack empty, while the other four testing conditions were randomized. Gait velocity was measured with a pressure sensitive computerized walkway for 5 trials each of the 6 conditions. ANALYSES: Velocity data were averaged for each subject from the five trails of each task condition. To determine if gait velocity changed between the loaded walking conditions, a Repeated Measures ANOVA was employed, with a p < .05. Post hoc analyses for pair-wise comparisons between all conditions were performed using paired samples t-tests with a Bonferroni corrected alpha of .01. RESULTS: Walking velocities significantly slowed for all loaded conditions when compared with unloaded walking (F = 2.763, p = .039). Specifically, when intermediate loading conditions of 7.5 lbs were presented, the mean velocity significantly lowered despite how the backpack was carried (two straps: t = 3.355, p = .006 and one strap: t = 3.179, p = .009). Although not significantly different, the full load of 15 pounds carried on one strap approached significance (t = 1.933.355, p = .079). No differences were found between baseline walking and full load with two straps. Additionally, both of the unloaded backpack conditions occurring at the beginning and the end of the study were not significantly different. CONCLUSIONS: Gait velocities decreased from the initial baseline trials under all loaded and strapped conditions and rates increased closer to initial levels when the packs were again unloaded. Carrying the loaded backpack with one or two straps did not appear to affect gait parameters. Surprisingly, the significant reductions in velocity occurred when walking with the intermediate load only. In healthy children, a loaded backpack should not weigh no more than 15% (about 1/6) of a student's body weight. Our data suggest that in the presence of lower extremity arthritis walking is negatively influenced when carrying backpacks of loads much less than this percentage. Further research is needed for the development of adequate guidelines for carrying backpacks in this population. FUNDING SOURCE: none KEYWORDS: gait, children, backpack, juvenile arthritis, velocity 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.