## 4 Discussion  
In terms of gamification, the aim is to create a comprehensive gamification environment. In this regard, BC networks, with their characteristic features, are very convenient for carrying out these initiatives. Leaderboards and the allocation of rewards and prizes contribute to motivating the completion of these challenges. Through the verification process conducted by the SCs, the users' progress in the respective challenges is automatically assessed. This allows for the assignment of their scores, their classification, and the distribution of their rewards.  
In addition to these elements properly described as gamification elements by [PERSON] et al. [14], this platform applies the model presented in [PERSON], [PERSON], et al. [10]. In this model, the delivery of a series of messages of different types (general, directed, and personalized, focused both on the benefit and the detriment) is organized to maintain direct contact with the user and encourage participation in the challenges.  
In light of the presented results, compared to similar proposals found, it is worth noting some similar examples, such as [PERSON] et al. [30], where healthy habits are encouraged by rewarding with system-specific cryptocurrencies, but with a very low level of development, Technology Readiness Level-3 (proof of concept in the laboratory).  
Figure 12: Metamask interface showing the Sepolia testnet.  
Conversely, in our proposal, the adherence to healthy challenges is supported by means of an interface that, according to the SUS results, seems friendly and simple, rewards users with cryptocurrencies, and encourages them to perform physical activity with motivating messages. In addition to this, it also complies with data protection laws by implementing the hybrid system represented in Figure 2.  
The proposals presented in [PERSON], [PERSON], et al. [31] and [PERSON], [PERSON], et al. [32] provided users with customized workout and feeding plans based on their anthropometric and body composition data using BC only to ensure data security and integrity and, again, with a low level of development. This proposal lacks a gamification environment and motivating messages. In [PERSON] et al. [33], a data storage system was created for tracking belt promotions in Taekwondo, ensuring that scores are recorded with transparency and immutability. The use of BC was not clear as it is simply used for its transparency and immutability features but without implementing any BC-specific service.  
Other existing solutions implement gamification environments, but in a traditional way without the benefits derived from this technology. This would be the case for [PERSON] et al. [34], in which they develop an application to promote healthy habits for people in wheelchairs, also checking the usability perceived by the system users. In [PERSON] et al. [35], they checked the usability of a chatbot called iHelpr to improve the mental health of the participants. In both solutions, the usability of the system presented to the users was checked, obtaining, in the first case, 58.6 points in the SUS, which indicates an average score in adjective ratings of \"Ok\", determined only by 14 users, compared to the average rating of our proposal of 80.49 points, rated as \"Good\", coming from the ratings of 71 users. Regarding the latter proposal, the iHelpr chatbot obtained an average score of 88.2, placing itself with a score of \"Excellent\" with the rating of only seven subjects, compared to our results, slightly lower at 80.49, obtained from 71 participants.