# Emotion-Driven Music and IoT Devices for Collaborative Exer-Games
## 2 Related Work
### Emotions in Exer-Games  
One conclusion that can be drawn from the previously discussed games is that music is typically selected during the design phase and remains the same for all players. To increase the effectiveness of music, it would ideally adapt to the progression of the game, players' performance, or their interactions with game elements. These adaptations could be based on the physical and emotional responses of players during different game activities [32]. Players' physiological signals could be monitored over time and analyzed to inform decisions that would allow for more flexible use of music.  
Heart rate is one of the most widely used physiological signals in sports, with the advantage that numerous low-cost devices are available for monitoring it. Ref. [33] presents a dancing game in which songs are selected according to the user's heart rate. Players' heart rates are measured to determine their physical exertion at any given moment, and the game integrates a feedback model to select the most appropriate song to regulate that exertion. These decisions are based on the relationship between the tempo of the songs (an acoustic characteristic) and the desired physical demands of each activity. However, this work does not account for players' physical training or experience, which is considered one of its main limitations [34]. Ref. [35] proposes a similar solution, combining heart rate and galvanic skin response to select songs from a limited discography (consisting solely of techno and orchestral music). Decisions are also based on the intensity of the music, and tests are conducted in different adventure games. Although the authors discuss the potential for integrating their solution into exer-games, no results are presented.  
In [11; 12; 13], various physiological signals are monitored to modify exer-game conditions or to analyze the criteria used in their design. Unfortunately, music is not incorporated into these research proposals. [PERSON]. [11] presents a cycling game, _Explore Orion_, where heart rate is used to increase or decrease pedaling speed or to suggest breathing exercises that promote relaxation. [PERSON]. [12] conducts experiments to identify the sources of stress experienced by players during gameplay, measuring stress levels through skin conductance and electrocardiograms. The study concludes that factors related to game interaction design and external stimuli are the primary sources of stress. Finally, [PERSON]. [13] analyzes the cardiovascular exertion of players during rounds of an exer-game, seeking to identify correlations between game design criteria and the physical benefits of the activities. In this study, heart rate is used to estimate the exertion of participants.  
Exer-games have the potential to elicit positive emotional responses in players, and these emotions, in turn, can influence the success and outcomes of the physical activities. This bidirectional relationship between exer-games and emotions is examined in [3], which concludes that exer-games improve emotional health, quality of life, and perceived well-being. These improvements are associated with reductions in anxiety, stress, and depressive symptoms, alongside increases in happiness, motivation, and vitality. Consequently, emotions should be inherently integrated into the control and progression of game activities. In [14], players' physiological data are translated into emotional states to dynamically configure background music. Artificial intelligence models and physiological signals are used to recognize these emotions, while an emotion-based game interaction system selects and synchronizes songs with the game's narrative.