appears on the display the zone alarm is on. You will hear a beeping sound with each heartbeat if your heartbeat is outside the heart rate limit. If you do not want to use the zone alarm the flashing heart rate reading indicates if your heartbeat is outside the heart rate limit. This function can be used if you have set heart rate limits on.
if you are exercising above heart rate zone. 
if you are exercising below heart rate zone.S510 specifications
The Polar S510 is a cutting-edge smartwatch designed for athletes and fitness enthusiasts who require advanced features to track and enhance their performance. With an elegant design and a rugged build, this device is tailored for those who push their limits in various sports and outdoor activities.One of the standout features of the Polar S510 is its precise heart rate monitoring. Utilizing advanced optical sensors, the watch provides real-time heart rate data, allowing users to optimize their training zones and maintain their desired intensity levels. This is complemented by Polar's unique Smart Coaching technology, which generates personalized training programs based on the user's fitness level and goals. These tailored recommendations help athletes train smarter rather than harder, fostering better results and reducing the risk of overtraining.
The watch supports a wide array of sport profiles, ranging from running and cycling to swimming and strength training. Each profile provides specific metrics tailored to the activity, including pace, distance, and calories burned. An integrated GPS ensures accurate tracking of outdoor workouts, while the watch’s waterproof design allows for use in all weather conditions and during swim sessions.
Another impressive aspect of the Polar S510 is its long battery life. With up to 40 hours of training time on a single charge, users can participate in extended workouts without the worry of their device dying mid-session. The smart notifications feature syncs with smartphones, providing users with alerts for calls, messages, and app notifications, ensuring they stay connected without interrupting their training.
The Polar S510 also employs advanced recovery tracking, helping athletes monitor their recovery status and readiness for subsequent workouts. The Nightly Recharge feature assesses sleep quality and recovery overnight, providing insights into overall well-being and performance readiness.
In addition to its fitness features, the watch also incorporates Polar Flow, an app that allows users to analyze their training data, set goals, and interact with a community of fitness enthusiasts. The comprehensive feedback and encouragement foster not just individual improvement but also a sense of camaraderie.
With its combination of stylish design, robust features, and sophisticated technology, the Polar S510 is not just a smartwatch; it is an indispensable training partner for anyone serious about reaching their fitness goals. Whether in the gym, on a trail, or in a pool, this smartwatch encapsulates innovation and performance in one powerful device.