Exergames (a portmanteau of “exercise” and “games”) are interactive video games that stimulate an active, whole-body gaming experience [1]. Exergames are gaining popularity, mainly, due to the growing interest in health improvement [2]. Depending on the purpose, exergames are classified into 3 categories, namely, exergames for (1) elite athletes’ training, (2) rehabilitation of patients, and (3) health improvement of general people [3]. Due to their requirements of large space and high costs, exergames have been traditionally used to train elite athletes or rehabilitate patients. However, recent years have witnessed cost reduction and miniaturization of exergames using technologies such as micro-electromechanical systems, which allowed the dissemination of various exergames to improve health of the general public [4].

Generally, high levels of an aerobic exercise are reported to enhance the concentration as well as exercise capability [5]. In addition, a fast video game has been reported to enhance concentration by requiring real-time monitoring for large information [6]. Conventional studies have suggested that an exergame, combined with high levels of aerobic exercise and a fast video gaming experience, enhances exercise capability and concentration [1]. However, a few exergames have been studied for their effect on the concentration of users [7]. Therefore, we would like to evaluate the effect of ski exergames with high level of aerobic exercise on the general public.

Although skiing is a popular sport, it is limited by environmental seasons and location. To address these limitations, ski simulators for indoor training, which can be used anytime and anywhere, have been developed [8-10]. Recently, the commercialization of ski simulators [11-13] has been useful in not only training elite athletes but also improving people’s health.

Ski exergames consist of a motion platform and virtual reality (VR) content. The motion platform enables users with the natural skiing experience through feedback (output) according to the input motion. The VR content provides the user with a virtual ski environment (with multimodalities such as vision and sound). The VR content suggests a challenging goal for motivation (competition and achievement), and the suggested goal improves the exercise capacity and concentration of the user [14]. In the ski exergame, concentration for finding a downhill route and exercise capacity for maintaining a posture are required, such as the actual ski motion. However, the conventional studies [15-17] evaluating the effect of ski exergames considered only the exercise capacity, not concentration. Therefore, this study investigates the effects of VR content–enabled ski exergame on the exercise capacity and concentration of the user. This study compares the effects of VR and non-VR exercise on the exercise capacity and concentration of users in the ski exergame.

The ROM of the ankle, as measured in the experiments, is shown in Figure 2. ROM of the ankle is the maximum range of rotation of the ankle joint in the sagittal plane in experiment 1 and experiment 2. The ROM of the ankle was 78.50° (SD 20.43°) and 115.71° (SD 17.71°) in experiment 1 and experiment 2, respectively, which implies that the ROM of the ankle in experiment 2 was wider than that in the non-VR exercise (P=.015).

RPEs for both the experiments are shown in Figure 3. RPE is the exercise intensity measured using a survey after experiment 1 and experiment 2. The RPEs were 4.10 (SD 1.85) and 2.20 (SD 0.42) for experiment 1 and experiment 2, respectively. However, we did not find any statistically significant difference between the RPEs of the 2 exercises (the non-VR exercise and VR exercise).

The EEG data measured from the experiments are listed in Table 3.

EEG is the ratio of brain waves measured from experiment 1 and experiment 2. We did not find any significant differences with respect to the Delta, Theta, Alpha, M-Beta, H-Beta, and Gamma waves. However, significant differences were observed with respect to the SMR wave (P=.017) between non-VR exercise and VR exercise. The ratios of sensorimotor rhythm wave in EEG were 2.70% and 3.08% in experiment 1 and experiment 2, respectively. The SMR wave is related to the concentration, and the corresponding results are favorable for VR exercise over non-VR exercise.

In this study, we investigated the effects of the VR and non-VR exercises on the exercise capacity and concentration of users in the ski exergame. To provide resistance between snow surface and ski plate, the ski motion platform was fitted with an elastic band that stretches linearly with the tension from the start of contraction to the maximum ROM of the ankle. Due to such mechanical characteristics of the system, it is hard for a user on the ski motion platform to maintain a balanced posture if the user is moving from side to side. Moreover, since it is harder to maintain the posture, the user has to significantly move the lower limb joints, including the ankle [15]. In this experiment, we found that the ROM of the ankle in the VR exercise was wider than that in the non-VR exercise. This implies that the VR content in the VR exercise induced a wider side-to-side movement (exercise) than the non-VR exercise, and the users rotated the ankle joint to larger angles to maintain the posture.

The SMR wave in an EEG occurs in the state of attention and activity. This type of wave is mainly observed if the subject is solving the problem that requires a simple concentration [19]. From the results of this experiment, we found that the SMR wave favors VR exercise more than non-VR exercise, which implies that VR content used in the VR exercise enhanced the concentration more than that in the non-VR exercise.

We found that VR content enhances challenge, motivation, and concentration by setting aims of higher gate-passing accuracy and reduced racing time. Our study confirmed that higher concentration could be achieved with VR exercise using VR content than with non-VR exercise. Exergame is expected to be used effectively by those who, in general, do not like exercise but enjoy the game. In addition, the people who spend many hours sitting may find ski exergame useful for their health maintenance.

Since the work presented here is based on a pilot study with a small sample size, it is difficult to generalize the results. Therefore, future work should focus on increasing the number of participants and duration of the experiments. Additionally, the changes in body composition of the subjects should be measured.

As exergames persuade users to exercise and enhance their concentration through leisure, these are used by the subjects of various categories such as children, adolescents, older people, and patients [20-23]. Exergames have been reported to enhance the physical activity in low- or mid-intensity exercise regimes, similar to walking or jogging [24,25], and cognitive function related to concentration [26]. However, it is not yet known whether these effects are achieved by VR exercise rather than non-VR exercise. Many conventional studies have shown that aerobic exercise or physical activity of moderate intensity is helpful in improving the concentration (related to cognitive abilities) of children [27-30]. The results of these studies do not elucidate which of the exercises (VR or non-VR) has a larger effect on concentration and exercise capacity. Therefore, the effects of exergame should be evaluated by considering the game and exercise factors separately in future studies.