# Influence of Body Weight Support Systems on the Abnormal Gait Kinematic
## 4 Discussion  
In this study, we aimed to examine and evaluate the effects of the ABWS and CW systems on an abnormal gait that looked like a hemiplegic patient. The abnormal gait was generated by restriction movement of the knee joint and 3 kg-weight on the ankle. Previous research has been shown the influence of the BWS system on healthy subjects, which only represented the changes of gait parameters of the healthy person during ambulation [23; 39; 40; 41]. Furthermore, the gait parameters were impacted by many external factors while implementation of the BWS in clinical of hemiplegic, stroke, and spinal cord injury patients such as assistance device, the support of the therapist, etc. [15; 19; 21; 22; 28; 29; 35; 38]. Evaluation of the changes in the gait parameter during abnormal gait under the BWS system would be necessary and provide useful information for clinical practice. The hypothesis assumed that the BWS system plays a role as a clinical intervention such that the BWS system would influence the gait patterns and parameters during rehabilitation. The assistance of the stepping movement by the BWS system, which changes the gait patterns and parameters of the abnormal walking, may alter and activate the sensory feedback, therefore, improve the ambulation functionality [20; 35; 37]. Our results confirmed that the BWS system would strongly alter the abnormal walking gait pattern and could play an important role in the clinical implementation of gait rehabilitation of the lower extremity. The ABWS and CW system generally cannot correct the extreme abnormal gait since the significant differences from the normal walking condition can be observed. However, the modification and improvement of the abnormal walking under the ABWS and CW system can be found. The results in Figure 5 and Figure 7 indicated that the ABWS system improved the gait parameters of abnormal walking in terms of COM, COP. The improvement was significant in the horizontal direction of COM and both sagittal and horizontal of COP. The CW system also improved the COM in the horizontal direction; however, it did not provide good result in term of COP. These improvements of stride length and the right step length can also be observed while using the ABWS system. These results agree with the previous research that the improvements in gait training could be achieved during weight supported by the BWS system [15; 22; 26; 28; 29; 38]. When comparing gait parameters between the ABWS system and the CW, the ABWS system provided better behavior in most cases. Currently, only a few studies conducted an experimental comparison between the active and passive unloading system [42; 48]. In this present study, the maximum displacements of the COM in the horizontal direction of the ABWS were significantly higher and closer to the normal walking condition, as shown in Figure 5. In Figure 6, The mean COP trajectory shapes of the walking under the ABWS system were more symmetry, the COP trajectories of walking under the CW system, contrarily, were more distorted and could not replicate the COP trajectory of the normal walking case. The quantifies of the maximum displacements of the COP while walking under the ABWS system was better and closer to the normal case. The CW system even provided the worse results of the maximum displacement of the COP during the right leg loading response and in the horizontal direction. This result confirmed the previous study such that the unloading force of the ABWS system with the COP tracking could provide better gait trajectories in comparison with the case of using the CW system with a constant counterweight [42]. These results could be explained that the lateral force in the pendulum effect by using the CW system pulled subject COM to the vertical center axis [23; 49]. Consequently, the COP in the horizontal direction would distort while walking under the CW system, especially at the high level of unloading force (see Figure 6).