| The treadmill has recently gained increased attention as a method for gait training and analysis. It is necessary to understand the relationship between overground (OG) and treadmill (TM) walking, in order to validate the clinical use of TM for individuals with neuromuscular disabilities. The primary purpose of this study was to examine biomechanical differences between OG and TM walking in children with and without cerebral palsy (CP) by comparing gait variables at an identical walking velocity. Perceptional differences were also assessed by comparing self-selected walking velocity between OG and TM. Group interactions with walking conditions were examined to determine which group had greater differences. This study involved 20 children with ambulatory spastic diplegic CP (age 10.75 ± 3.27, males: females = 10:10) and 20 children without CP (age 11.35 ± 2.91), matched on age and gender. All subjects performed both OG and TM walking three times at an identical comfortable walking velocity. They also completed three probe trials for each walking conditions to obtain self-selected comfortable and fastest walking velocities. The Vicon 3-D motion analysis was used to assess differences in 12 gait variables. Analyses of variance with repeated measures revealed statistically significant differences in cadence, stride length, peak lower limb joint kinematics and ROM (range of motion) between OG and TM walking. For both CP and control groups, significantly increased cadence (all ps < 0.004) and shorter stride length (all ps < 0.004) were noted during TM walking. In the CP group, significantly increased peak angles of ankle dorsi-flexion, knee flexion, knee extension, hip flexion; increased ankle and hip ROMs; and decreased pelvic rotation ROM were found during TM walking compared to OG (all ps < 0.004). In the Non-CP control group, only decreased peak ankle dorsi-flexion and decreased ROMs in ankle and pelvis were found during TM. The group interaction analyses with mixed model ANOVAs showed that the CP group had greater differences between OG and TM walking. The results indicate that the different task and environmental constraints of TM walking may alter gait patterns of children. The differences between OG and TM walking appear to be greater in children with CP, compared to those without CP. The differences should be considered for treadmill-based gait experiments and clinical intervention. |
