ORIGINAL ARTICLE The Influence of Applying Additional Weight to the Affected Leg on Gait Patterns During Aquatic Treadmill Walking in People Poststroke Taeyou Jung, PhD, ATC, DoKyeong Lee, MS, Charalambos Charalambous, MS, Konstantinos Vrongistinos, PhD ABSTRACT. Jung T, Lee D, Charalambous C, Vrongistinos K. The influence of applying additional weight to the affected leg on gait patterns during aquatic treadmill walking in people poststroke. Arch Phys Med Rehabil 2010;91:129-36. Objective: To investigate how the application of additional weights to the affected leg influences gait patterns of people poststroke during aquatic treadmill walking. Design: Comparative gait analysis. Setting: University-based aquatic therapy center. Participants: Community-dwelling volunteers (n=22) with chronic hemiparesis caused by stroke. Interventions: Not applicable. Main Outcome Measures: Spatiotemporal and kinematic gait parameters. Results: The use of an ankle weight showed an increase in the stance phase percentage of gait cycle (3%, P=.015) when compared with no weight. However, the difference was not significant after a Bonferroni adjustment was applied for a more stringent statistical analysis. No significant differences were found in cadence and stride length. The use of an ankle weight showed a significant decrease of the peak hip flexion (7.9%, P=.001) of the affected limb as compared with no weight condition. This decrease was marked as the reduction of unwanted limb flotation because people poststroke typically show excessive hip flexion of the paretic leg in the late swing phase followed by fluctuating hip movements during aquatic treadmill walking. The frontal and transverse plane hip motions did not show any significant differences but displayed a trend of a decrease in the peak hip abduction during the swing phase with additional weights. The use of additional weight did not alter sagittal plane kinematics of the knee and ankle joints. Conclusions: The use of applied weight on the affected limb can reduce unwanted limb flotation on the paretic side during aquatic treadmill walking. It can also assist the stance stability by increasing the stance phase percentage closer to 60% of gait cycle. Both findings can contribute to the development of more efficient motor patterns in gait training for people poststroke. The use of a cuff weight does not seem to reduce the limb circumduction during aquatic treadmill walking. Key Words: Exercise therapy; Gait; Hemiparesis; Rehabil- itation; Stroke. © 2010 by the American Congress of Rehabilitation Medicine S TROKE IS THE THIRD leading cause of death and one of the most common medical conditions that yield long-term disabilities among adults in the United States. 1 Stroke survivors show various neurologic deficits including motor, sensory, cognitive, perceptual, emotional, and speech-language impair- ments. The primary motor impairments involve paresis, altered muscle tone, lack of selective motor control, abnormal reflexes, and poor balance. 2 A combination of these motor characteris- tics often compromises gait. The majority of people poststroke (50%– 80%) typically recover their ability to walk, whereas approximately 20% of stroke survivors remain primarily wheelchair users. 3 Even though they may recover mobility, many encounter various difficulties with their gait, such as slow walking speed, inefficient energy expenditure, altered gait kinematics, limited gait endurance, and poor gait stability, when compared with healthy adults. 4-8 The most common gait pattern found after a stroke is hemiparetic gait, which is asso- ciated with asymmetric spatiotemporal and kinematic gait char- acteristics. The paretic limb of people poststroke shows altered step length, decreased single-limb support time, reduced hip and knee joint angles, and increased ankle plantarflexion an- gle. 4,9-14 In addition, compensatory motor patterns are often observed during the hemiparetic gait, such as circumduction, vaulting, and pelvic hike. 2,15,16 Overground, treadmill, and treadmill with BWS are com- monly used modes for stroke gait rehabilitation. Although a treadmill is traditionally used for an exercise mode among healthy individuals, it is clinically used for locomotor rehabil- itation in individuals with mobility impairment. Research- ers 17-19 found that people poststroke decreased step length and increased cadence, stance phase percentage, single-limb support phase, and stance/swing ratio on the affected limb while walking on a treadmill as compared with overground. The changes in their gait patterns during treadmill ambulation are often associated with the improvement of gait symmetry. 18 The effects of treadmill-based gait training have been well From Center of Achievement, Department of Kinesiology, California State Uni- versity, Northridge, Northridge, CA (Jung, Vrongistinos); Center for Human Motor Research, Division of Kinesiology, University of Michigan, Ann Arbor, MI (Lee); and the Motor Behavior and Neurorehabilitation Laboratory, Division of Biokinesi- ology and Physical Therapy, University of Southern California, Los Angeles, CA (Charalambous). Presented in part to the American College of Sports Medicine, May 29, 2008, Indianapolis, IN. Supported by the Graduate Thesis Support Grant Program, California State Uni- versity, Northridge, CA (grant no. E2134). No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit on the authors or on any organi- zation with which the authors are associated. Correspondence to Taeyou Jung, PhD, ATC, Dept of Kinesiology, California State University, Northridge, 18111 Nordhoff St, Redwood Hall, Northridge, CA 91330, e-mail: taeyou.jung@csun.edu. Reprints are not available from the author. 0003-9993/10/9101-00386$36.00/0 doi:10.1016/j.apmr.2009.09.012 List of Abbreviations ANOVA analysis of variance BWS body weight support CI confidence interval 3-D 3-dimensional 129 Arch Phys Med Rehabil Vol 91, January 2010