Adults with Parkinson ’ s Disease Undergoes Exergaming Training to Improve Balance : A Systematic Review

Abstract—Parkinson’s disease (PD) is a neurodegenerative disease, which is affecting millions of people globally. One common problem in PD patients are postural instability which can lead to balance control impairment. PD patients’ postural instability is currently one of the most difficult challenges the physician encounters when treating the patients with this long duration of disease. However, previous studies have shown that exergaming is a popular treatment for improving balance of PD patients. The purpose of this study was systematic review of exergaming training intervention and outcomes of balance among participants with PD. The search terms “exergaming,” “exergames,” “balance,” “Parkinson’s disease” “Virtual reality” and “Postural instability” were used in three electronic databases, Science direct, Pubmed and Scopus. eleven studies were systematically reviewed using the synthesis matrix. The results indicated that the exergaming training group of PD participants ranged from 1 to 76. The training duration and frequency was between 20 minutes to 60 minutes, one to three times a week, for a period of 6 to 12 weeks. In terms of research methodology, most studies reviewed conducted randomized controlled trial, while two studies administered semi-experimental design and one study conducted single subject experimental design. The results of these studies indicated many benefits of exergaming training among PD participants, such as, balance, gait, fatigue and postural instability. In conclusion exergaming intervention is recommended as postural stability treatment for PD participants. This study may be used as a guide for future reference when designing exergaming balance training for future studies or rehabilitation application.


I. INTRODUCTION
Parkinson's disease (PD) is a worldwide illness, with an occurrence rate of 4.5 to 19 people per 100 000 populations per year [1] (World Health Organization, 2006). PD is a neurodegenerative disease, which is affecting seven million people globally [2] (Zafari, Amiri, & Taherian, 2017) and known to effect individuals' postural instability [3] (Lee, Altmann, McFarland, & Hass, 2016). The instability of the postural may be present in the early stage of the disease and become worse as the PD progresses [4] (Jankovic, 2008). It is found that the frequency of individuals with Parkinson's disease (PD) fall twice as much as neurotypical people [5] Manuscript received September 14, 2019; revised December 15, 2019. Yu-Tai Wu is with the Department of Physical Education, National Taiwan Normal University, Taiwan (e-mail: tarrywu2005@gmail.com).
Yu-Feng Wu is with the Graduate Institute of Sport, Leisure and Hospitality Management, National Taiwan Normal University, Taiwan (corresponding author; e-mail: garywu821822@gmail.com).
Jian-Hong Ye is with the Department of Industrial Education, National Taiwan Normal University, Taiwan (e-mail: kimpo30107@yahoo.com.tw). (Allen, Schwarzel, & Canning2013). Postural instability among individuals with PD not only lead to balance control impairment, an increase in fear of falling and losing balance confidence [6] (Adkin, Frank, & Jog, 2003).
According to [1] World Health Organization (2006) PD patients face many difficulties, such as, freezing of gait, postural instability and falls, which are associated to patients' balance. In addition, PD patients face many neuromechanical impairments, such as anticipatory postural adjustments (APAs) and automatic postural reactions (APRs) that affects the movement coordination and postural instability [7] (Carpenter, Allum, Honegger, Adkin, & Bloem, 2004; [8] Massion, 1998). Furthermore, the joint stiffness is also a common problem postural responses. In fact, these play out to be a great influence to postural influence even when standing. Postural instability is currently one of the most difficult challenges the physician encounters when treating the patients with this long duration of disease [1] (World Health Organization, 2006).
However, exergaming is a popular intervention, as can be seen, in recent years' technologies such as virtual reality and exergaming software, is increasing rapidly in neurological rehabilitation [9] (Mirelman, Maidan, & Deutsch, 2013). Games that involves in exercising while playing for health benefits, which requires the movement of the body in order to continue with the game and helps increases physical activity levels is known as "Exergames". Convincingly, exergaming holds promises that it is more effective comparing to other programs that contain physical activity [10] (Gao, Chen, Pasco, & Pope, 2015). Therefore, exergaming may be an implement for avoiding or decelerating the pace of losses in postural control and functional balance.
According to the embodied learning theory, which comprises learning activities with the requirement of body engagement and provides people with improved knowledge retention and learning performance. People's thought and reasoning have been argued that embodied cognition are deeply associated to the sensorimotor, at the same time as the interaction of physical environment is connected to the body [11] (Barsalou, 1999;[12] Glenberg, 2010. Moreover, embodied learning requires that the individuals have a meaningful connection, where learning is required to be associated with physical, embodied experience [13] (Merriam, 2008).
In the world today, technology is advancing its growth in a fast pace, which allowed the capabilities of interface within digital technology to gradually enable people to have connection with computers easier than ever [14] (Jacob et al., 2008). In recent years, the technology advancement has become easier for individuals to interact, taking mobile phones and tablet computers for example, these technologies have made it an easy movement with augmented camera views making the physical interface combining with virtual and physical settings, which is now known as "mixed reality" [15] (Milgram & Kishino, 1994 Resnick (2006) specified that "conceptual leverage can be led by digital technologies so that learners to accomplish embodied activities Augmented viruality (AV) is known to improve people embodiments. The AV includes interfaces that requires interaction and devices that can bring elements to the real world, known as virtual reality environment, this environment is regarded as "mixed reality" [15] (Milgram & Kishino, 1994; [20] Simsarian & Akesson, 1997). This environment not only bring sense of presence, as well as giving individuals feedbacks and interactions [21] (Kim, Prestopnik, & Biocca, 2014). Exergaming is an example of augmented virtuality, since it has virtual environment where motion devices are performed. For example, pressure sensors or devices that is able to track the motions of the body. These devices allow people to experience the real world, and the exergames allows it to respond to the gestures and physical activity of the user [22] (Won, Bailenson, & Janssen, 2014).
The research designs, exergaming intervention designs and outcomes of previous studies all differ significantly. Thus the purpose of this study was systematic review of exergaming training intervention and outcomes of balance among participants with PD. In addition, this study aims to identify the benefits of exergaming training in improving balance among participants with PD. The results in this study may be used as a guide for future reference when designing exergaming balance training for future studies or rehabilitation application.

II. METHODS
To conduct this systematic review, a synthesis matrix was used. This type of method is widely used in literature review, especially in health sciences. In this study, the matrix consists of columns and row, where the column is composed of variables and topics, and the rows composed of literature. A critical analysis method such as synthesis matrix is often used to develop future research.
In this study, the search terms were used "exergaming," "exergames," "balance," "Parkinson's disease" "Virtual reality" and "Postural instability". The search covered three electronic databases, Science direct, Pubmed and Scopus were searched, from 2013 to 2019, to identify relevant studies. In addition, this study only included studies in English and articles that were not theoretical, introductory or review articles. Participants without Parkinson disease and studies with traditional exercise for balance training were excluded from the search. There were four reviewers that conducted the systematic review. The first reviewer was a doctoral student from graduate institute of sport, leisure and hospitality management. The second reviewer was a professor from the same institute, while the third and fourth reviewer was doctoral student from department of physical education and department of industrial education. To ensure the accuracy of the selection of studies, four reviewer did a cross comparison while discussing together.
Several criteria were used in the selection of the articles. First all studies that used qualitative analysis were excluded in the study. Second exergaming therapy for balance was the intervention of all the studies. Finally, 82 articles were identified in the searching process. However, studies that included other types of balance therapy and other types of disease were excluded in the study. After the elimination of duplicates and irrelevant studies 11 studies were analyzed. The following flow chart of the searching process can be seen in the Fig. 1 below.

III. RESULTS
In this study, 11 articles were used in the synthesis matrix. First, the experimental designs discussed in Table I were assessed to the type of intervention, such as participants, group types, approach and the Parkinson disease stages of the participants. Second, in Table II the results indicated the type of kits, the type of training and the duration and frequency of each experiment conducted in the 11 studies. Lastly, Table III shows outcome indicator and findings.

A. Participants
In the studies reviewed, each indicated the number of the participants that participated in their study. As can be seen, studies conducted by [  Fit has balance board is convenient to measure the balance of the participants. All training games played by the participants were all related to balance or postural stability. However, there were some limitations when using Wii Fit and Xbox Kinect kit, the sample size was not large for all the studies except for the study that used visual reality [23] (Gandolfi et al., 2017). Thus, this can be that visual reality exergaming were able to conduct a larger sample size compared to Wii Fit and Xbox Kinect.
It is notable that the training games used were fun and challenging in these studies, which can enhance participants interest while training their balance and postural stability. Moreover, embodied learning requires that the individuals have a meaningful connection, where learning is required to be associated with physical, embodied experience [13] (Merriam, 2008). As can be seen these games have all acquired embodied experiences and that it can be a stated as "conceptual leverage" as these digital technologies can accomplish embodied activities [19] (Resnick, 2006).

E. Duration and Frequency
The duration of the exergaming training was between 20 minutes to 60 minutes while in most studies 30 minute sessions were the most common duration of the exergaming balance training for the PD participants, while 50 minute sessions were the second most among the studies. Most of the studies frequency of the exergaming training intervention were twice a week over 6 weeks and 8-week period. The longest frequency was over a 12-week period intervention. (see Table II)

F. Outcome Indicator
All studies reviewed used scales and software's to measure the PD participants balance or postural stability which can be seen in Table III. The common scales used to determine balance was with Berg balance scale. Moreover, scales and measurements related to balance and functional stability conducted in the reviewed studies were Berg scale, Falls risk test, Stability index, Tinetti scale, Falls Efficacy Scale-International, Mini-Balance Evaluation Systems Test, Dynamic Gait Index, timed Up-and-Go test, Limits of stability (LOS), One-leg stance (OLS), Tinnet's Performance-Oriented Mobility Assessment, Activities-specifi Balance Confidence scale. Thus, there will be different findings on exergaming intervention on balance among participants with Parkinson's Disease.

G. Findings
Exergaming has showed significant balance improvement among PD participants Balance-based exergaming training gained a positive effect in the postural stability when comparing to conventional balance training [27] (Shih et al., 2016). According to [24] (Liao et al., 2015). Another study mentioned that virtual reality exergaming can be an alternative to in-clinic, as it can reduce postural instability in PD patients [23] (Gandolfi et al., 2017).  . As can be seen these games have all acquired embodied experiences and that it can be a stated as "conceptual leverage" as these digital technologies can accomplish embodied activities [19] (Resnick, 2006).
Furthermore, the results also showed that 10 sessions and 15 session have the same effect on balance performance among PD patients [25] (Negrini et al., 2017). Exergaming training for balance positively improved the postural instability when comparing with conventional balance training [27] (Shih et al., 2016). In addition, another study found that exergaming also had positive effect improving balance and fatigue reduction in PD patients after 12 weeks of training. However, this benefit did not continue in the long-term. In conclusion, exergaming intervention is recommended as postural stability treatment for PD participants.

V. CONCLUSION
PD is a neurodegenerative disease, which effects millions of people globally [2] (Zafari, Amiri, & Taherian, 2017). Which in result PD participants encounter postural instability in the early stage of the disease and become worse as the PD progresses [4] (Jankovic, 2008). As the PD progresses patients fall as much as neurotypical people [5] (Allen, Schwarzel, & Canning2013). This becomes a problem, since postural instability are found to be a difficult challenge for physician when treating the PD patients [1] (World Health Organization, 2006). Thus exergaming can become can be an alternative to in-clinic sensory integration balance training (SIBT), as it can reduce postural instability in PD patients [23] ( Gandolfi et al., 2017).
In recent years, exergaming training is a popular intervention, which is increasing rapidly in neurological rehabilitation [9] (Mirelman, Maidan, & Deutsch, 2013). In the world today, technology is advancing its growth in a fast pace, which allowed the capabilities of interface within digital technology to gradually enable people to have connection with computers easier than ever [14] (Jacob et al., 2008). Therefore, exergaming for balance training can provide easier access for PD patients. Different kinds of technologies include interfaces that requires interaction such as Wii Fit, Xbox sensor and virtual reality that bring elements of the real world [15] (Milgram & Kishino, 1994; [20] Simsarian & Akesson, 1997).

VI. LIMITATIONS AND FUTURE STUDIES
There were some limitations to this study. First, the studies identified to meet the eligible criteria was limited. Second, the review of the studies included many types of interventions, types of controls, measurement of results, and quality of methodologies. Third, considering that only published journal from three electronic databases, "Science direct", "Pubmed" and "Scopus" were used and that the search terms were only limited to "exergaming," "exergames," "balance," "Parkinson's disease" "Virtual reality" and "Postural instability". Finally, the search was limited to English publications, both publication bias and language bias can occur.
The results in this study may be used as a guide for future reference when designing exergaming balance training for future studies or rehabilitation application. As can be seen, the rehabilitation of the games and kits were games not designed specifically for adults with PD. Future studies may design games that focus on the needs of PD participants, including appropriate content, interface design and game needs. Future studies should indicate the standard measures of PD disease such as (Hoehn and Yahr ) [30]