# Direct Mobile Coaching as a Paradigm for the Creation of Mobile Feedback Systems
###### Abstract  
In sports feedback systems, digital systems perform tasks such as capturing, analysing and representing data. These systems not only aim to provide athletes and coaches with insights into performances but also help athletes learn new tasks and control movements, for example, to prevent injuries. However, designing mobile feedback systems requires a high level of expertise from researchers and practitioners in many areas. As a solution to this problem, we present Direct Mobile Coaching (DMC) as a design paradigm and model for mobile feedback systems. Besides components for feedback provisioning, the model consists of components for data recording, storage and management. For the evaluation of the model, its features are compared against state-of-the-art frameworks. Furthermore, the capabilities are benchmarked using a review of the literature. We conclude that DMC is capable of modelling all 39 identified systems while other identified frameworks (MobileCoach, Garmin Connect IQ SDK, RADAR) could (at best) only model parts of them. The presented design paradigm/model is applicable for a wide range of mobile feedback systems and equips researchers and practitioners with a valuable tool. s +
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not only be used to collect data in such scenarios but also help to improve data quality. For example, some participants in a study might face difficulties exercising at the correct prescribed intensities. In such cases, dedicated feedback can help athletes follow prescribed intensities [6], thus improving overall data quality. The last decades have brought vast improvements in technology relevant to this field of application. In particular, the miniaturisation of sensors and enhancements in wireless technologies have created an enormous potential for feedback systems [7]. Furthermore, the enhanced battery life of sensors is another factor contributing to the ability to conduct studies not only in laboratory settings but also in real-world scenarios. This enhancement of battery life is also due to the development of wireless data transmission standards such as \"Advanced and Adaptive Network Technology\" (Ant+) or \"Bluetooth Low Energy\" (BLE). Another challenge is that the currently available solutions are limited in their customisability and do not allow the modelling and creation of a wide variety of feedback systems. Current tools are often tailored for one specific sport (e.g., cycling) or type of sport (e.g., endurance sport) or type of feedback (e.g., terminal feedback by means of charts). Furthermore, they often rely on proprietary technology, thus hindering the ability to replicate experiments with other technologies. Yet another problem is that details concerning data protection and privacy, such as where data is processed and stored, are often not transparent. This paper aims to answer the question of how researchers and practitioners can be aided in the creation of mobile sensor-based feedback systems. As a solution to the challenges discussed above, this article introduces Direct Mobile Coaching (DMC), a paradigm for the creation of mobile feedback systems. It allows modelling state-of-the-art applications for collecting and processing sports and motion-related data. Furthermore, its applicability to a wide variety of use cases is shown. The model addresses the challenge that the potential of novel technologies in sport science can often not be fully exploited by domain experts due to their complexity. The novelty of the approach lies in the combination of a model-based domain-specific abstraction layer, which enables the rapid building of feedback systems for various use cases without in-depth technical knowledge, with an open and highly adaptable technology layer that allows the integration of novel sensor and processing technologies without the limitations usually imposed by vendor-specific systems. Consequently, this article describes the architecture and details of Direct Mobile Coaching.