# Influence of Body Weight Support Systems on the Abnormal Gait Kinematic
## 1 Introduction  
Hemiparesis and impaired ambulation are commonly resultant of spinal cord injury and stroke [1, 2]. According to the National Spinal Cord Injury Statistical Center (the United States (US)), the estimated number of people with SCI living in the United States is approximately 291,000 persons, with a range from 249,000 to 363,000 persons, about 17,730 new SCI cases (equivalent to 54 cases/million population) each year [3]. The number of incidents per million people per year varies widely by country, such as 27 in Japan [4], 13.4 in Switzerland [5], 12.7 in France [6], and 57.8 in Portugal [7]. Also, a report from the American Heart Association showed that an estimated 7.0 million Americans \(\geq\)20 years of age had a stroke [8]. The ratio of patients be able to walk again after recovery from SCI is only from one fourth to one third [9, 10, 11, 12]. In terms of stroke patients, the new sufferers of stroke in the US are from 795,000 cases, about 26% remained disabled in necessary activities of daily living, and about 50% have reduced mobility due to hemiparesis [2]. Hemiparesis, locomotor disability, and impaired ambulation made an adverse impact on the daily life quality of the patient and cost up to billions of dollars for health care expenditures [2, 13]. In recent studies, the Body Weight Support (BWS) system was considered to be an indispensable component in gait training systems that have been used to improve the ability to walk of hemiplegic, stroke, and spinal cord injury patients. The BWS system was used in many locomotion rehabilitation systems regardless of whether treadmill-based systems [14] or ground-based systems [15]. The evolution of the BWS system for gait training was based on the observation of the recovery of spinal cord cutting cats when implementation gait training for them with the weight-support and the full weight [16; 17]. The application of the treadmill BWS system was then extended for the human gait training. [PERSON] et al. investigated the influence of BWS on human gait [18]. Their findings showed that the Treadmill BWS system expressed the advantaged behaviors in every examined aspect and had potential extensive applicability in clinical gait training. The application of [PERSON] et al. examined the differences between weight support and full weight-bearing in locomotor rehabilitation with 100 stroke-patient participation [19]. The results confirmed that gait training for a patient who was supported by the BWS provided walking ability better than the patient training with bearing full weight. The BWS system, then, is widely applied in locomotor rehabilitation from the laboratory to clinical [15; 20; 21; 22; 23; 24] for both overground walking training [15; 25; 26] and treadmill walking training [23; 27; 28; 29]. In recent years, the Treadmill BWS system in conjugation with orthosis robots was applied for many gait training systems to reduce the therapy cost and labor [30; 31; 32; 33; 34]. The BWS system, currently, was theoretically considered to be a clinical intervention in neuro-rehabilitation [35; 36]. The principle of BWS training as an intervention is to improve motor performance by supplying the injured nervous system with the appropriate sensory input [37]. The influence of the BWS system on gait parameters while training has been investigated, such that the BWS system showed promise and potential as a clinical treatment that improves the locomotor function and ability to walk of hemiplegic, stroke, and spinal cord injury patients [15; 19; 21; 22]. For example, [PERSON] et al. indicated that patients with stroke could walk better while their weight was supported [19]. [PERSON] et al. showed that the walking ability of the nonambulatory patients with cerebral palsy was improved after walking training on the treadmill with a part of body weight supported [27]. Walking speeds of the spinal cord injury patients were improved after training with the BWS system and electrical stimulation [38].