INTRODUCTION

The increase in life expectancy has been observed worldwide and has generated the inversion of the population pyramids of several countries around the world [1]. The aging process causes several physiological changes that can have important consequences for health, such as those associated with postural control and maintenance of balance, as well as cognitive deficits [2]. The conventional physiotherapy for elderly fallers focuses on the improvement of balance and mobility and consists of therapeutic exercises for gain of strength and range of motion [3]. It is known that the cognitive deficit is also related to the increased risk of falls [3]. Choi states, that physiotherapy has treatments and exercises aimed at preventing falls of older people, but it still faces several challenges such as: increase initial engagement to therapy; ensure regularity and intensity of therapy, including activities at home; ensure concentration during therapy activities; combining motor-cognitive stimuli; security during the activities [4].

Recent studies show that the use of exergames may be effective for the rehabilitation of balance and in reducing the risk and incidence of falls in conventional physiotherapeutic treatment [4,5,6,7,8]. Exergames involve motor and cognitive dual task activities, and can promote improvement in cognitive-motor function, degree of independence and adherence of individuals to therapy [7]. One of the limitations of the exergames commonly used nowadays is that they were not designed for clinical rehabilitation, therefore, they do not contain the degree of specificity necessary to perform the function of rehabilitating patients with cognitive-motor deficits [8].

In addition, commercial exergames are not being developed specifically for cognitive-motor training for the elderly and neurological patients [8].

We present an under development immersive exergame with cognitive-motor activities focused for elderly fallers, and an evaluation based on tests results with experts.

METHODS

Study Design

We applied a mixed-methods survey-based study. First, each participant answered a questionnaire about daily technological use, to examine familiarity with video game and virtual reality headsets. A second questionnaire was applied to identify any previous health issues or discomfort with virtual reality (VR). Next, the participant played one the two solutions of the exergame during 5 minutes. Then, answered a 5 point scale post-test questionnaire about health side effects to verify safety and tolerability and a 5 point Likert scale about user satisfaction about the game. After that, the participant played the other implementation for 5 minutes and answered the same two questionnaires. At the end, each participant wrote his/her impressions and thoughts about the two implementations of the exergame.

Half of the participants played a different solution first.

Participants

We have collected information from 6 experts, Brazilian physiotherapists experienced in working with elderly people. They were separated in two groups. Group 1 tested one solution first, and then other. Group 2, tested in the other order. To participate of the study the physiotherapist was not above 120kg; without high or low blood pressure; and without color blindness, assessed through the Ishihara test [9].

The two exergame solutions automatically collected, for each participant, the score, correct answers, wrong answers and where the game stopped when the time was over.

Exergame design and implementation

We developed a virtual reality exergame, named Balloons, where a player must make the highest score possible by popping balloons, presented on a park scenario (figure 1), in a specified time (5 minutes, for the tests presented here). To score, the player must make sums exactly equal to 10, and not above, popping ballons of two different collors: pink which values 1 and green which values 2 for the sum. If a player completed a sum exactly equal to 10, he would receive 10 points in the game (and 1 correct mark is computed) and the counter would go back to 0. If a player completed a sum equal to 11, it does not receive points in the game (and 1 incorrect mark is computed) and the counter would go back to zero.

Considering that the participant would use a head mounted display (HMD) and would move fast and frequently, to avoid cybersickness we took some precaution in the design of the game, configuring the game engine to increase the field of view (FOV) of the camera. This way, the user can see more objects and therefore, reduce unneeded head movement.

The exergame was developed using Unity 3D 2018® and Microsoft Visual Studio 2017®, Microsoft’s tutorial asset for beginners windows mixed reality development in Unity and an asset player controller from Cyberith for the omnidirectional treadmill (ODT). The 3D assets of the park scenario were purchased on Unity asset store, 3D warehouse website for the balloon model. Theme song was downloaded from youtube's video creator and the sound effects on https://freesound.org.

Gameplay

Before starting the chronometer, the player can explore the environment to become familiar with the scenario and the interaction mechanisms. To start the game, the player must touch a white cube, that will disappear, and the game starts in 3 seconds. Balloons would appear randomly, moving from bottom to up, just like a balloon with helium in real life. To score, the player needs to think and respond quickly popping balloons until he reaches a sum of exactly 10. The player must move around the scene in order to reach the balloons with his hands, using the controllers.

Equipment

We have implemented two different solutions for playing the same game Balloons using the same HMD and 2 controllers, the Samsung® HMD Odyssey Windows Mixed Reality Headset from the windows mixed reality platform plus with 2 wireless controllers. In one solution the participant uses a vest attached to an overhead harness (Figure 1a) for security, avoiding falls and collisions. In the other solution he uses a virtual reality omnidirectional treadmill (ODT), the Cyberith® Virtualizer Elite, developers’ version (Figure 1b). This ODT was designed specifically to be used with VR headsets, and it has a flat and slippery surface where users are hold on a ring supported by 3 pillars, allowing the user to feel like walking to any direction, but, limited inside the ring. All participants were assisted to get in and out safely.

RESULTS AND DISCUSSION

As the results were quite similar with the two solutions we have implemented and tested, we combine the two sets of answers (6 answers for each of the two solutions, given a total of 12 answers for each questionnaire).

Observing the results presented at Figure 3, we can see that in ten aspects related to discomfort after VR, all participants report none discomfort at all. In four aspects we had one report of some discomfort and in just one aspect we had two reports of some discomfort.

The results presented at Figure 4 show that among eleven affirmations, in eight of them the participants reported to agree or strongly agree in more than 80%.

We had two reports that the participants strongly disagree or disagree that they found it easy to move within the virtual scene to approach the balloons. More tests, after some adjustments in the game, changing the positioning of the balloons, should be done to investigate if it can reduce this problem.

In four answers the participants reported that felt uncomfortable wearing HMD glasses. The technology has evolved a lot, but the HMD did not reach 100% acceptability. It is still a little bit heavy.

In eight of twelve answers the participants reported that they strongly disagree or disagree that they did physical exercise to be able to perform the tasks of the game. More tests, adjusting the positioning and velocity of the balloons, and changing the duration of the test are required to investigate this aspect. However, it can have impact in the discomfort.

CONCLUSIONS AND FUTURE WORK

The results presented indicate positive evaluation by experts in terms of safety, tolerability and acceptability.

However, they also indicate the need of some adjustments in the difficult level (giving the possibility of adjustment by the expert), a lack of exercise intensity and the necessity of adding more cognitive activities and challenges to the game and content.

The calibration ODT must also be improved, increasing its sensitivity to make it easier for the user to move. Another important technical issue is related to HMD, a wireless and lighter HMD could give better acceptability.