## 2 Materials and Methods
### Action Registration in the System
#### 2.3.3 User Interface  
As previously indicated, users have access to a web interface through which they can interact with the system. Specifically, Figure 9 displays its login page and confirmation page, which includes an encouraging message to stimulate users' participation. Upon logging in, the user can access the functionalities described in previous sections. In this way, access is universal, as any device provided with a browser can use the system.  
The Planking challenge used to verify the effectiveness of this prototype requires maintaining a proper abdominal plank position for a certain duration, replicating the posture of the \"prone plank test\". This involves supporting the body's weight on the toes and forearms while lying face down with a neutral pelvis position [38, 39]. Users log into the proposed dApp, get into the described position, and, using the stopwatch provided in the interface, they control the duration of the exercise. The moment they lose this correct position, they stop the stopwatch, record the duration of the activity, and receive a confirmation message and motivation to continue taking part in the challenge. Rewards are presented to the user on two distinct occasions during the challenge: first, when they correctly perform an abdominal plank, and second, when they achieve the overall challenge, which requires performing the actions for 15 consecutive days. These rewards are distributed in the form of the platform's tokens, which are backed by the BC. Figure 10 shows a user testing the application with the provided interface for this purpose  
Figure 8: Excerpt of the code responsible for verifying the execution of actions and facilitating the dispatch of pertinent messages.  
Figure 9: User interface for the event registry for the plank challenge and reward assignation.  
with a stopwatch to control the duration of the exercise and the final motivation panel to continue with the practice of physical activity.  
The actions that users must record in this challenge are, therefore, the duration of each abdominal plank each time they perform it by means of the dApp provided to implement this healthy habit. In the pilot deployed for testing purposes, a healthy population group was chosen, consisting of 71 users (44 men and 27 women) with an age of 18.5 \(\pm\) 3.2 years (mean \(\pm\) SD). According to the gamification model, rewards should be given in an automatic and transparent way to reinforce the habit. For this, the developed dApp verifies the fulfilment conditions and assigns rewards when appropriate, as previously discussed.  
In the scenario of the developed prototype, there is a SC in place. Its role is to validate the fulfilment of the challenge requirements and allocate the suitable reward. This reward is given in the token of the testnet utilized for deploying the prototype, namely Sepolia, in this instance. In addition to the reward received by the users to incentivize their participation, they receive emails following the model described in previous sections. Furthermore, to cultivate the desired gamification atmosphere, users have the ability to monitor their own progress as well as that of others, thereby promoting a sense of healthy competition among them.