Underwater communication devices typically suffer from large size and high power consumption, which pose significant challenges for real-time monitoring of swimmers’ heart rate and distance. To tackle these challenges, this study successfully developed a wearable acoustic-Bluetooth dual model communication-based real-time heart rate monitoring and ranging system (WARM) for swimmers by implementing an integrated miniaturized acoustic transducer design, narrow-pulse OOK modulation, and acoustic multipath interference suppression techniques. The final self-developed system measures 47 mm × 36 mm × 18 mm and weighs 54 g. Six swimming volunteers were recruited to conduct underwater real-time heart rate monitoring and distance measurement experiments for performance evaluation of this self-developed system. Experimental results demonstrate that within an effective communication range of 2500 cm, the system achieved an average transmission power consumption of 52–58 mW, a frame loss rate of only 1.1%, and a mode-switching time of 1–2 s between the underwater acoustic and Bluetooth transmissions. In addition, the system enabled real-time heart rate monitoring and underwater ranging, with an average ranging error below 50 cm. These results verify the reliability and stability of the proposed system and provide a useful reference for the design and application of wearable underwater communication systems.
The human body posture and trajectory are important parameters of the optimal path in speed climbing, and current researchers are focused on them. However, the performance of the newly developed analysis tools for synchronously and accurately analyzing climbing posture and trajectory is limited. This study develops an innovative speed climbing analysis system (SCAS) that integrates three-dimensional trajectory tracking using HTC Vive trackers and full-body posture capture with BlazePose. And the system is validated. Climbing trials were recorded from twelve professional athletes (speed climbers, eight males and four females; age 22 ± 2.2 years, all with ≥1 year of competitive experience) on a standard International Federation of Sport Climbing (IFSC) speed wall. The SCAS’s accuracy was analyzed by comparing its trajectory measurements to a video-based reference: the mean deviation was 0.061 ± 0.005 m (mean ± SD, 95% confidence interval [0.058, 0.064] m), indicating high precision. Trajectory metrics between genders were compared using independent-sample t-tests, revealing that male climbers had significantly shorter average path lengths (p < 0.05) and fewer movement inflections than female climbers. Finally, the group-optimal path derived from the data showed only slight deviations from the top-performing climbers’ paths. The proposed SCAS enables synchronous, millimeter-level tracking of climbing trajectory and posture, and can provide coaches with quantitative feedback for each athlete’s climbing strategy.