1 Journal of Sport Rehabilitation, 2009, 18, 1-16 © 2009 Human Kinetics, Inc. Laboratory Gait Analysis in Patients With Low Back Pain Before and After a Pilates Intervention Juliana Limba da Fonseca, Marcio Magini, and Thais Helena de Freitas Objective: To evaluate the infuence of pain on vertical ground-reaction force (VGRF) in patients with low back problems and the effect of the Pilates method on the gait of these patients. Design: A single-blind randomized controlled trial. Participants: 28 individuals assigned to a control group (n = 11) and a low-back group (n = 17), the latter of which was subdivided into a Pilates group (n = 8) and a no-Pilates group (n = 9). Intervention: The Pilates group undertook 15 sessions of Pilates. Main Out- come Measures: The VGRF parameters were recorded during preferred and faster walking speeds. The data were collected before and after the intervention. Results: The weight-acceptance rate and push-off rate were signifcantly less in the right lower limb of low-back group than of the control group at preferred speed. Improvements were seen in the Pilates group postintervention, with increased middle-support force for the left lower limb at faster walking speed and decreased pain; this did not occur in the no-Pilates group. Conclusions: These results suggest that patients with low back pain use strategies to attenuate the amount of force imposed on their body. The Pilates method can improve weight discharge in gait and reduce pain compared with no intervention. Keywords: vertical ground-reaction force, exercise therapy, rehabili- tation Low back pain is the most common of all skeletal-muscle problems. It has been estimated that 80% of adults at least once in their lives will suffer an episode of back pain suffciently severe that it will make them stop working temporarily. 1 Two syndromes might be recognized: common low back pain and low back pain with referred leg pain. In common low back pain, no important irradiation occurs, but in low back pain with referred leg pain, the pain is spread to the buttocks, posterior face of the thigh, and the feet. 2 The etiology of low back pain is not clearly defnite because of multiple risk factors associated with the condition. Some of these factors are repetitive motion, curvature and torsion of the spine, pushing and pulling activities, stumbles, falls, and static or sitting work posture. 3 One important mechanical function of the lumbar spine is to support the upper body by transmitting compressive and shearing forces to the lower body Fonseca is with the Dept of Biomedical Engineering; Magini, the Research and Development Institute; and de Freitas, the Dept of Health Sciences, Paraíba Valley University, São José dos Campos, Brazil. JSR GALLEY PROOF