## 1 Introduction  
The outbreak of the coronavirus disease (COVID-19) the world over in 2020 has triggered unprecedented political, financial, and social crises and cultural transformations, and the prolonged pandemic, ironically, has accelerated the cutting-edge technology-based fourth industrial revolution [1, 2]. Going beyond the scope of online communication and consumption, the realization of work, education, and travel in virtual spaces, such as augmented reality (AR) and metaverse, has made smart devices an indispensable part of people's lives in modern society [3]. However, it has also resulted in musculoskeletal disorders and obesity in people leading sedentary lifestyles for prolonged periods of time [4, 5]. Particularly, abdominal obesity among women has markedly increased in relation to childbirth, postural imbalance, and diminished physical activity [6, 7] As of 2020 in South Korea, 40% of the adult population is obese, and the average daily sedentary time among women is 7.8 h, an increase from that before the COVID-19 pandemic [8]. According to recent studies, despite a diet plan and exercise, a sedentary lifestyle itself induces abdominal obesity because of pelvic imbalance and reduced core and glutel muscle strength [9]. Further, a BMI of 30 kg/m\({}^{2}\) or higher increases COVID-19-related mortality by causing reduced immune functions [10, 11]. However, with professional manpower and administrative focus directed toward measures for disinfection amid the global crisis caused by COVID-19, the gravity of obesity and secondary metabolic disorders is currently underestimated, and measures for their prevention and treatment have been put on hold [4, 12]. Abdominal obesity causes various metabolic diseases because of the large number of cytokines from fat cells. These cytokines cause inflammatory diseases, which have a positive correlation with abdominal obesity [13; 14; 15; 16; 17]. Therefore, despite the COVID-19 environment, efforts should be made to increase the amount of physical activity. In order to manage weight gained by the viral environment, the American College of Sports Medicine (ACSM) recommends 150 min of aerobic exercise per week [16]. In addition, it was said that high-intensity exercise for more than 75 min helps reduce fat, and non-face-to-face participation in exercise can be an alternative [18]. The HIIT effect is already known through previous studies [19; 20; 21]. However, there are very few cases of online HIIT in the COVID-19 situation. High-intensity interval training (HIIT) involves a repetition of short, vigorous exercise followed by a short break to maximize energy consumption in a short period of time and is thus known as a time-efficient exercise for metabolizing fat [10]. It has gained popularity since it ranked second in the 2020 ACSM fitness trend [19]. Recently, studies have proposed that HIIT is more helpful in preventing cardiovascular diseases, rapidly improving glucose regulation in patients with diabetes mellitus [19; 20], and effectively reducing abdominal fat and blood cytokines in postmenopausal women compared to moderate intensity continuous training (MICT) [13]. Additionally, [PERSON] et al. (2020) reported that HIIT is less boring than MICT, while relieving stress [21], increasing physical fitness, and improving vascular functions [10]. Despite the greater health benefits and time efficiency compared to MICT, beginners or obese individuals are reluctant to actively utilize HIIT due to the risk of joint damage or injury [22; 23]. However, with professional guidance and feasible options that ensure safety and engagement, HIIT can be useful in promoting physical activity and preventing obesity in inactive, sedentary individuals. A \"new normal\" has been established since the outbreak of COVID-19, whereby people have begun enjoying online challenges and sports in virtual reality using the Global Positioning System (GPS) and various smart device-based platforms [24].