As the coronavirus disease 2019 (COVID-19) pandemic continues to develop in almost all regions of the world, the government has implemented various protective measures in response, including the closure of schools and universities, restrictions on travel and sporting events, and bans on social gatherings [1]. Individuals were ordered or advised to stay at home during the pandemic, with all these measures intended as effective strategies to prevent the spread of the virus and manage individuals infected with the virus [2]. While many individuals correctly followed official advice to self-quarantine and stay at home, these behaviors negatively affect their physical activity (PA) behavior and increase sitting time, and further affect well-being, sleep patterns, physical health, and quality of life [2]. The adverse effects of lack of PA on physical health are well established [3,4]. Implementing non-contact physical training programs during the pandemic, which can extend from weeks to months, can reduce the adverse physiological effects of sedentary behavior.

Digital healthcare technology has been developing rapidly in recent years, with various health-promoting equipment being developed. Owing to advances in industrial technology, wearable technology can provide new opportunities to motivate individuals to improve their PA levels, including mobile phone applications, smartwatches, wristbands, and other wearable devices [5]. Wearable technology refers to comfortable customer-based products with a simple and personalized interface [6]. In addition, wearable technology has a high market share because of its high availability, accessibility, and affordability [7]. The advantage is that users do not require many precautions and can use the product in their daily life [6]. The combination of wearable devices and smartphone apps provides a new platform that can help improve an individual’s health behaviors [6]. A systematic review reported that people using wearable devices had increased PA and daily steps, regardless of their physical characteristics and health condition [8]. Previous studies on PA intervention using wearable devices showed that when postmenopausal women performed 16 weeks of moderate-to-vigorous physical activity (MVPA) and 10,000 steps of walking, their MVPA per week increased by 62 min and the daily average number of steps increased by 789 steps [9]. Wearable devices not only increase PA but also have a positive effect on weight loss and chronic disease management [10-12]. Therefore, this study aimed to evaluate the effects of a 12-week non-contact exercise intervention on body composition and health-related physical fitness in adults.

The present study examined the effects of non-contact exercise intervention for 12 weeks on body composition and health-related physical fitness in adults. The findings of this study revealed that the non-contact exercise intervention reduced percent body fat and increased fat-free mass, skeletal muscle mass, hand grip strength, sit-and-reach, sit-ups, and VO_2max.

In recent years, studies on the effects of mobile health on body composition have drawn attention [13]. A tailored lifestyle self-management intervention (TALENT) study reported that intensive web-based lifestyle interventions showed effective results, with an average weight loss of approximately 10% and a decrease in BMI, fat mass, and percent body fat [14]. Although previous studies did not use wearable devices for interventions [14], the results are consistent with our findings. Meta-analysis studies have verified that wearable technology intervention periods of 12 weeks or more are more effective for reducing BMI results than interventions of less than 12 weeks [6]. In addition, a weight-loss program using an activity tracker worn during exercise can provide an effective short-term intervention (less than six months) for middle-aged adults [15]. Similar to our study, interventions using the Fitbit wrist activity tracker showed positive changes in fat-free mass among overweight male and in percent body fat among overweight female [16]. A previous study using mobile applications with push notifications for PA and diet management reported a decrease in weight and fat mass in obese women [17]. Therefore, exercise interventions using wearable devices can improve body composition.

Since health-related physical fitness is associated with the prevalence and mortality of diseases, it is essential to manage health-related physical fitness by increasing PA [18,19]. Owens et al. [20] reported that 21 individuals in 8 households performed a PA intervention using Wii Fit for three months, resulting in no significant change muscle strength, muscle endurance, flexibility, and aerobic capacity. This result was due to the absence of increase in moderate-intensity PA over the three-month period, resulting in a lack of physiological stimulation and low exercise intensity using the Wii Fit [20]. Avila et al. [21] reported that 150 min of home training per week, with an intensity of HRR of 70-80%, for 12 weeks in 90 patients with coronary artery disease showed a tendency to increase VO2peak, grip strength, and flexibility. Home training for patients with coronary artery disease effectively maintains health-related physical fitness over the long term [21]. Tallner et al. [22] reported that web-based PA using the MS-intact program positively affects muscle strength and lung function in patients with multiple sclerosis. However, web-based PA intervention studies should be conducted for at least ten weeks to be effective [23]. In line with these findings, the present study, which used exercise prescription and monitoring with smart tracker and mobile phone applications, obtained positive results for terms of health-related physical fitness.

The present study revealed that 12 weeks of non-contact exercise intervention improves body composition and health-related physical fitness among adults. Wearable technologies encourage individuals to improve their lifestyles by increasing PA and achieve the goal of maintaining health in this population.