# Real-Time Feedback in Swimming Exercises Using Embedded Devices in Water
## 4 Discussion  
All testing procedures and results were supervised by a professional swimming coach, who validated both the training movements and the in-water evaluations. The performed strokes adhered to the front crawl technique and were executed in a drill-like manner, rather than as continuous swimming. The system has proven to be reliable for dryland applications and as noted by the coach, can effectively support technique development through simulated swimming exercises. It is suitable for use across all swimming styles--not only front crawl, as explored in this study, but also breaststroke, backstroke and butterfly. Given its sequential structure and capacity for movement recognition, the system is particularly well-suited as a dryland simulator to assist swimmers in learning and refining specific techniques. Regarding in-water use, the results are promising. With targeted improvements, the system has the potential to function as an independent swimming assistant, providing real-time feedback via the integrated vibration motors to support stroke correction during training. In its current state, the system presents several limitations for in-water application:  
* Inconsistent in-water training: Due to the influence of water movement in the pool, maintaining stable arm positions is difficult. Additionally, the need to stay afloat  
Figure 17: Big swimming pool testing data transmission. introduces variability in movement, making it challenging to perform a technically perfect stroke repeatedly for pattern training. These conditions impact the consistency of training data. * Accelerometer sensitivity to full-body movement: As the IMU nodes are attached to the swimmer's arm, each stroke induces forward propulsion, causing the entire body to accelerate. This effect, combined with the necessary use of leg kicks for buoyancy, introduces additional acceleration values that deviate from the intended motion pattern [30]. * Condensation within waterproof enclosures: The use of sealed plastic bags for waterproofing, combined with the heat generated by the electronic components, leads to condensation inside the enclosure. This occurs due to the temperature difference between the device and the surrounding pool water, potentially impacting long-term reliability and sensor performance [31; 32; 33]. * Lack of continuous monitoring: Currently, the voting routine operates in a start-stop mode. Implementing continuous motion monitoring would allow the swimmer to vary speed or technique more naturally, with the system identifying movement patterns and delivering real-time feedback accordingly. Despite these challenges, the system demonstrates potential for in-water use, particularly if the similarity scoring formula is adjusted to be less sensitive to minor deviations. Such a modification would make the system more suitable for novice swimmers who are in the early stages of technique development and may benefit from approximate feedback rather than precise professional-grade evaluation, as targeted in this study. Moreover, the current system reads both accelerometer and gyroscope data from the sensors to compute the similarity output. To enhance the robustness of the voting phase--particularly in aquatic environments where linear acceleration is more susceptible to disturbance--the contribution of accelerometer data could be reduced in favor of a greater emphasis on gyroscope (rotational) data. This adjustment would shift the evaluation from an equal weighting of both parameters to a rotation-dominant approach, potentially improving classification accuracy in the presence of external perturbations. This paper does not validate the proposed system at a large scale. The primary focus is to evaluate the system's response, in the described configuration, during the calibration, training, and voting phases performed in a water environment. Additionally, it assesses the Wi-Fi communication between the slave nodes and the master node.