Keywords

1 Introduction

1.1 Rowing Training

As pointed out by Guangju (2017), rowing training in China now faces problems such as physical restrictions, closed training patterns and limited training venues [1]. In the study on the characteristics of rowing beginner’s training, Zaihang (2018) suggested that indoor rowing machine training should be carried out as the basis of on-water training [2]. Xiaoyan (2017) proposed an intelligent visualization improvement of rowing machines and conducted comprehensive analysis and evaluations of rowers’ training indicators [3].

1.2 Training in VR Environment

In recent years, virtual reality technology has developed as a popular tool that has brought changes in many fields. Xu (2018) found that VR technology in physical education and training could produce immersive experiences for students and enhance the teaching effect [4]. Qing and Yuanfei (2016) pointed out that physical requirements (i.e. venues, equipment and environments) in physical education (PE) restricted the conduction of many courses, and that a VR environment could create immersive experiences in a visual world and serve for the teaching purposes [5]. Jingyu (2017) designed a VR-based serious game for Rococo art teaching, combining technology, education and gamification [6]. The study of Murray et al. (2016) proved that VR could improve performance and the affective response to aerobic exercise [7]. Hoffmann et al. (2013) highlighted the importance of VR technology as a means to learn an energy-related skill and improve performance [8]. Brett et al. (2018) emphasized that challenge levels should be considered in the design of VR-based exercise programs and in matching competitive interactions among exercisers in virtual environments [9].

1.3 Gamification Theory

Gamification is the application of game-related elements in non-game contexts. Gamification has been applied to many fields such as business, marketing, management, health and education [10]. Many studies have explored the effectiveness of gamification in education and training. In the study on the effect of gamification-based task design on self-regulated learning, Dongjian (2018) demonstrated gamification’s effect in enhancing learners’ motivation, participation and learning outcomes [11]. Rob (2018) and others proved the motivational effects of gamification theory in education [12]. Lihua (2011) pointed out that motivational measures, as an important incentive mechanism in gamification, could stimulate the trainees and thereby improve the quality of military training [13]. In terms of gamification design, Werbach (2012) proposed the PBL (points, badges, leaderboards) method of gamification design [14], and ten of the most common game mechanics were perfected by Schell (2014): challenges, opportunities, competition, collaboration, feedback, resource acquisition, rewards, trading, rules, and winning conditions [15]. In rowing training, Wenzheng (2012) designed a rowing machine game in terms of both hardware and software [16].

Many experiments have been conducted to test sport training within a VR-based simulated environment, and almost all suggested that VR environment could effectively improve the training performance. The VR simulation experiences of rowing at present, however, are mostly generated using projectors or screens to produce dynamic virtual environments of simulated outdoor rowing, which does not necessarily have the desired effect. This study built on the Unity platform a VR rowing environment that applies to the HTC Vive and rowing machines (i.e. ergometers), allowing exercisers to feel fully immersed in a simulated rowing environment. Based on the motion principles and competition formats of rowing and the game mechanics in gamification theory, the study gave an in-depth analysis of the contents and logic of the rowing game, and extracted suitable game contents such as competition, leaderboard and resource acquisition.

2 Method

2.1 Participants

20 university students completed the International Sports Activity Questionnaire (IPAQ-SF) [17] and constituted the convenience sample. There were no significant differences in participants’ age, BMI, physical activity level and physical health.

2.2 Apparatus

Hardware

The experiment was completed in a 5 m × 4 m light-controlled room set with a temperature of 15°C. The hardware equipment included physical equipment, control center and VR equipment. Participants rowed on the Concept 2 Model D Indoor Rowing ergometer fitted with Performance Monitor 4 set with a distance of 300 m and a 1-level drag factor. The control center was a computer with Unity4 installed. And the VR devices consisted of HTC Vive, VR controllers and two laser position sensors (as shown in Fig. 1.).

Fig. 1.
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Hardware equipment for gamification-based VR rowing simulation system

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Software

This study built on the Unity platform a VR rowing game that applies to the HTC Vive and rowing ergometers. The HTC Vive controller was connected to the rowing ergometer handle to obtain real-time physical position of the VR headset and the handle, detect position changes of the ergometer and the participant, and based on the changes construct a rowing movement model. As participants rowed on the ergometer wearing a VR headset and holding the oars with controllers, the computer would record the position of the VR headset and oars and compare it with the previous position to infer participants’ movements and simulate human and boat movements in the VR environment, creating simulated rowing process for participants in the VR game.

Specifically, first the tracks, boats, end signs, landscapes and other objects were drawn in Unity. Then, the boat was set as the main object, and the headset and controllers the sub-objects on the boat. Code scripts were bound on these objects to obtain their position of each frame.

This experiment established a series of incentive and reward mechanisms in the game. A number of boats with the speed set to a random number within a certain range would compete with the participants. The game levels had progressively increasing difficulty (i.e. the speed of competing boats increases) to appeal to participants. Real-time ranking and speed were displayed and participants would be awarded according to the ranking when the game ended. Besides, rowing scores would appear on the leaderboard, and the points could be accumulated to redeem different items in the game shop, such as boat skins and modification tool.

2.3 Measures

International Physical Activity Questionnaire – Short Form (IPAQ-SF)

The International Physical Activity Questionnaire – Short Form (IPAQ-SF) was used to classify participants into one of three categories of physical activity (low, medium, and high). The IPAQ-SF has seven items asking participants about the amount of time spent engaging in various forms of exercise over the last 7 days. The IPAQ-SF is positively correlated with exercise level and physical fitness.

Physical Activity Enjoyment Scale (PACES)

Physical Activity Enjoyment Scale [18] was used to measure the enjoyment of physical activity. The scale consists of 16 statements relating to physical activity. Participants respond to the statements on a Likert scale. PACES contains 9 positively-keyed questions and 7 negatively-keyed questions which are summed to produce the total enjoyment score. Higher scores suggest higher level of enjoyment.

User Experience Questionnaire (UEQ)

User Experience Questionnaire (UEQ) was used to obtain a preferably comprehensive impression of the product user experience. The 26-item questionnaire includes six factors: Attractiveness, Perspicuity, Efficiency, Dependability, Stimulation, and Novelty.

2.4 Procedure

On arrival, 20 participants provided informed consents and health certificates and then completed the IPAQ-SF. The height, weight and BMI of participants were measured. Participants on normal rowing ergometers were set as the control group, and those using VR rowing simulation system as the experimental group. Professional coaches gave participants instructions on correct rowing techniques. All participants were given a 5-min warm-up period rowing on the ergometer for familiarization with the equipment and performance feedback.

The experiment began after a 10-min rest. All participants were asked to row 300 m on the ergometer and were informed every 100 m. After the 300-m rowing, participants’ heart rate in 30 s as well as the rowing time and stroke rate shown on PM4 were recorded. Then participants complemented the PACES and the UEQ.

To eliminate the influence of drops in energy levels, 20 participants were constructed to complete the row in VR simulation system after 24-h rest. The experimenters explained to participants the VR environment and game rules. Next, participants were fitted with VR headsets and completed a 5-min free rowing for warm up and familiarization with the equipment and performance feedback.

The experiment began after a 10-min rest. All participants were asked to row 300 m in a gamification-based VR simulation environment (as shown in Fig. 2.) and were informed every 100 m. After the 300-m rowing, participants’ heart rate in 30 s as well as the rowing time and stroke rate shown on PM4 were recorded. Then participants complemented the PACES and the UEQ.

Fig. 2.
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Participants in the experiment

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2.5 Scoring and Statistical Analysis

Prior to statistical analysis, time data were converted to seconds for analysis. Next, Paired-Samples T-tests were conducted to compare the heart rate, finishing time and stroke rate in the control group and the experimental group. In all analyses, α was set as 0.05.

3 Results

3.1 Physiological Indicators

Heart Rate

Null hypothesis: the heart rate of participants in a gamification-based VR rowing simulation system (experimental group) would not be higher than those rowing on normal ergometers (control group).

Alternative hypothesis: the heart rate of participants in a gamification-based VR rowing simulation system (experimental group) would be higher than those rowing on normal ergometers (control group).

As shown in Table 1, t = −9.723, p < 0.001, df = 19, the null hypothesis was rejected. In terms of heart rate, significant differences between the control group (M = 69.25) and the experimental group (M = 78.70) were found as the difference between the two means statistically significantly different from zero at the 5% level of significance. Specifically, the results suggest that the experimental group experienced higher exercise intensity and quality compared with the control group that had lower heart rate.

Table 1. T-test results of heart rate
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Finishing Time

Null hypothesis: the finishing time of participants in a gamification-based VR rowing simulation system (experimental group) would not be shorter than those rowing on normal ergometers (control group).

Alternative hypothesis: the finishing time of participants in a gamification-based VR rowing simulation system (experimental group) would be shorter than those rowing on normal ergometers (control group).

As shown in Table 2, t = 8.852, p < 0.001, df = 19, the null hypothesis was rejected. In terms of finishing time, significant differences between the control group (M = 102) and the experimental group (M = 89.3) were found as the difference between the two means statistically significantly different from zero at the 5% level of significance. Specifically, the results suggest that compared with participants in the control group, participants in the experimental group experienced enhanced exercise performance with improved speed and body strength.

Table 2. T-test results of finishing time
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Stroke Rate

Null hypothesis: the stroke rate of participants in a gamification-based VR rowing simulation system (experimental group) would not be higher than those rowing on normal ergometers (control group).

Alternative hypothesis: the stroke rate of participants in a gamification-based VR rowing simulation system (experimental group) would be higher than those rowing on normal ergometers (control group).

As shown in Table 3, t = −7.738, p < 0.001, df = 19, the null hypothesis was rejected. In terms of stroke time, significant differences between the control group (M = 102) and the experimental group (M = 89.3) were found as the difference between the two means statistically significantly different from zero at the 5% level of significance. Specifically, the results suggest that the experimental group experienced showed better exercise quality and motivation compared with the control group with lower stroke rate.

Table 3. T-test results of stroke rate
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3.2 Psychological Indicators

Physical Activity Enjoyment

Null hypothesis: the physical activity enjoyment of participants in a gamification-based VR rowing simulation system (experimental group) would not be greater than those rowing on normal ergometers (control group).

Alternative hypothesis: the physical activity enjoyment of participants in a gamification-based VR rowing simulation system (experimental group) would be greater than those rowing on normal ergometers (control group).

As shown in Table 4, t = −12.040, p < 0.001, df = 19, the null hypothesis was rejected. In terms of physical activity enjoyment, significant differences between the control group (M = 102) and the experimental group (M = 89.3) were found as the difference between the two means statistically significantly different from zero at the 5% level of significance. Specifically, the results suggest that the VR rowing simulation system could greatly improve participants’ physical activity enjoyment, raise their exercise motivation and reduce their anxiety levels.

Table 4. T-test results of physical activity enjoyment
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User Experience Impression

Results of the UEQ showed significant differences among the control group and the experiment group, as the average score of each item in two groups suggested (p = 0.001 < 0.05). Specifically, compared with traditional rowing machines, the gamification-based VR rowing simulation system could provide better user experiences especially in interestingness and ingenuity.

4 Discussion

Findings of the present experiment show that rowing in a gamification-based VR simulation environment increased performance as measured by finishing time, heart rate and stroke rate when compared to rowing without VR input, which indicates that the VR rowing simulation system can produce an improvement in exercise intensity and quality. The results of the PACES show that the application of gamification theory can improve the participants’ enjoyment and motivation in the exercise. And the UEQ results show that the VR rowing simulation system provides better user experience in terms of interestingness and ingenuity.

Although participants of the present study were all university students, the findings could apply to professional rowing athletes. Long practices on the rowing ergometer would cause stronger anxiety for athletes, and the VR rowing simulation system could reduce their anxiety and improve their training enjoyment and motivation.

The findings of this study are likely to generalize to other training and exercises. For example, a VR parkour game could be designed for running on the treadmill, which requires new research paths and design principles.

This study designed a gamification-based VR rowing simulation system that innovatively combined the rowing machine and VR headset to produce greater immersion. With VR technology, rowing exercise is no longer subject to on-water training requirements, and the gamification-based game contents enhance the playability of rowing. The use of VR simulation system could be expanded in rowing training to promote the development of rowing and national fitness.

Several limitations of the present study need to be considered when interpreting the results. First, the game content richness and the virtual environment reality could be further improved. In addition, the relatively short rowing distance and small sample size may affect the experiment results.

The present study is an interdisciplinary study in the industrial design and sports field. The gamification-based VR rowing simulation system is a Human-Computer Interaction (HCI) product that explores new paths in rowing training using new technologies and is of great relevance in the application of gamification theory in sports training. Findings of this research could be further generalized to other sports.