Hindawi Publishing Corporation Parkinson’s Disease Volume 2013, Article ID 572134, 9 pages http://dx.doi.org/10.1155/2013/572134 Research Article Exploring Outcome Measures for Exercise Intervention in People with Parkinson’s Disease L. A. King, 1,2 A. Salarian, 1 M. Mancini, 1 K. C. Priest, 1 J. Nutt, 1 A. Serdar, 3 J. Wilhelm, 3 J. Schlimgen, 3 M. Smith, 3 and F. B. Horak 1 1 Department of Neurology, Oregon Health and Science University, Portland, OR 97239-3098, USA 2 Parkinson Center of Oregon, OP32, 3181 S.W. Sam Jackson Park Road, Portland, OR 97239-3098, USA 3 Department of Rehabilitation Services, Oregon Health and Science University, Portland, OR 97239-3098, USA Correspondence should be addressed to L. A. King; kingla@ohsu.edu Received 12 February 2013; Accepted 28 March 2013 Academic Editor: Terry Ellis Copyright © 2013 L. A. King et al. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Background. It is widely believed that exercise improves mobility in people with Parkinson’s disease (PD). However, it is diicult to determine whether a speciic type of exercise is the most efective. he purpose of this study was to determine which outcome measures were sensitive to exercise intervention and to explore the efects of two diferent exercise programs for improving mobility in patients with PD. Methods. Participants were randomized into either the Agility Boot Camp (ABC) or treadmill training; 4x/week for 4 weeks. Outcome measures were grouped by the International Classiication of Function/Disability (ICF). To determine the responsiveness to exercise, we calculated the standardized response means. -tests were used to compare the relative beneits of each exercise program. Results. Four of ive variables at the structure/function level changed ater exercise: turn duration ( = 0.03), stride velocity ( = 0.001), peak arm speed ( = 0.001), and horizontal trunk ROM during gait ( = 0.02). Most measures improved similarly for both interventions. he only variable that detected a diference between groups was postural sway in ABC group ( = 4.95;  = 0.03). Conclusion. Outcome measures at ICF body structure/function level were most efective at detecting change ater exercise and revealing diferences in improvement between interventions. 1. Introduction he progression of Parkinson’s disease (PD) inevitably results in problems of balance, contributing to injuries, loss of mob- ility, increased health costs, and decline in quality of life. Delaying and minimizing these inevitable complications of PD with physical therapy exercise would have a major impact on patients and their families’ quality of life, healthcare sys- tems, and possibly even the course of disease progression. Exercise has received much attention in the past decade as a way to delay the onset of mobility disability and there are a steadily increasing number of randomized controlled trials demonstrating that varying types of exercise improve some aspects of balance or gait [1–12]. However, it is diicult to determine whether a speciic type of exercise program is more efective than another. One recurring obstacle, which makes it diicult to compare treatment approaches, is that studies use diferent types of outcome measures [13]. In addition, exercise studies almost always compare their favored type of intervention with a placebo or no intervention, rather than a head-to-head comparison of diferent types of exercise programs. he diiculty in comparing 2 potentially efective rehabilitation interventions is the need for very sensitive tests of change and a large number of subjects to diferentiate exercise programs. Although there is evidence from the animal literature that diferent exercise protocols result in diferent efects on synaptic and structural proteins in the brain, diferentiat- ing functional improvements in humans ater diferent types of exercise has been more diicult to demonstrate [14]. For example, studies in rodents made Parkinsonian from 6- hydroxydopamine show that aerobic exercise on a treadmill results in increased angiogenesis whereas agility exercise that provides a mental challenge results in more synaptic plast- icity [15]. However, a recent meta-analysis of human exercise studies could not distinguish relative beneits among the