## 1 Introduction
Another key feature of this model is the use of events, which are crucial for service traceability. These artefacts, so-called events, serve as information dissemination mechanisms. From a functional point of view, they are entries in the blocks of data, like any other transaction. In addition to regular entries, events include topics to facilitate their discovery and support for data logging. It has the additional advantage of not having an associated expenditure of network resources for its generation, unlike what happens with transactions in general. Therefore, the issuance of these events on the network constitutes a simple and efficient mechanism for notifying circumstances that take place on the network itself. In this way, it is possible to inform all users of internal events on the network in a simple way. Services intended to take advantage of gamification strategies can use this feature, as they offer a simple and cost-effective, in terms of resources, way to track achievements within the platform. This new paradigm of decentralized data is also quite suitable for the delivery of solutions using new approaches. To maximize the potential of this model, it is typical to utilize decentralized applications (dApps) for both mobile and traditional platforms. These applications are often hosted in a P2P setting, utilizing BC or other P2P networks to manage data and logic. The functional guidelines for these dApps are typically implemented as SC [23; 24]. This technology has evolved to be used in environments very different from cryptocurrencies, such as Business Process Management [25], anti-counterfeiting [26], supply chains [27], or healthcare [28]. This kind of platform largely benefits from the interoperability between different BC networks to perform cross-blockchain token transfersand cross-blockchain SC invocation and interaction [21]. Achieving this milestone allows different entities or companies to cooperate more efficiently in complex environments. The suggestions for employing blockchain technology in the domains of physical activity, exercise, sports, and active aging are still undeveloped, as many of the distinctive attributes of blockchain, like smart contracts, are not fully utilized yet. Currently, as indicated in [PERSON] et al. [29], the proposals for the use of BC in the domain of healthy practices are in an immature state, as many of the distinctive attributes of BC, like SC, dApps, events, and others, are not fully exploited. However, it is worth mentioning some proposals in which, to a certain extent, some of these characteristics are applied to improve habits or quality of life in their users. For example, [PERSON] et al. [30] suggested a platform designed to encourage exercising and support wellness-oriented living by incentivizing participants with his/her own cryptocurrency for reaching their goals on a BC platform. In [PERSON], [PERSON], et al. [31] and [PERSON], [PERSON], et al. [32], they provided users with customized workout and feeding plans based on their measurements and body composition details; the use of BC was merely for safety. In [PERSON] et al. [33], a data storage system was created for tracking belt promotions in Taekwondo, ensuring that scores were recorded with transparency and immutability. In all these proposals, BC technology is used in one way or another, but without full utilization as indicated in [PERSON] et al. [29]. Nevertheless, the practical implementation of those proposals, according to the authors, is quite limited. Also, it is worth mentioning that there are other applications in which gamification has been implemented, but in a traditional way, i.e., without the use of this technology. That would be the case for [PERSON] et al. [34], in which an application to promote healthy habits in people in wheelchairs was developed. In [PERSON] et al. [35], authors checked the usability of a chatbot called iHelpr to improve the mental health of participants.