GPS tracking is not a common feature of fitness trackers, as it requires a more powerful battery and can be more expensive to implement.

ECG is the most accurate way to measure heart rate, as it directly measures the electrical activity of the heart. Optical heart rate monitoring and PPG are less accurate, as they rely on indirect measurements of heart rate.

Fitness trackers are not typically used to improve sleep quality. However, they can be used to track sleep patterns and provide insights into sleep quality.

The recommended daily step count for adults is 10,000 steps.

Chest straps are not a type of fitness tracker. They are typically used to measure heart rate during exercise.

Accuracy is the most important factor to consider when choosing a fitness tracker, as it determines how well the device measures your activity and other health metrics.

The Garmin Vivosmart 4 is known for its long battery life, which can last up to 7 days on a single charge.

The Garmin Swim 2 is the best fitness tracker for swimming, as it is waterproof up to 50 meters and has a number of features specifically designed for swimmers, such as stroke recognition and distance tracking.

The Garmin Forerunner 245 is the best fitness tracker for running, as it has a number of features specifically designed for runners, such as GPS tracking, pace and distance tracking, and heart rate monitoring.

The Garmin Edge 1030 is the best fitness tracker for cycling, as it has a number of features specifically designed for cyclists, such as GPS tracking, speed and distance tracking, and elevation tracking.

The Garmin Fenix 6X Pro is the best fitness tracker for hiking, as it has a number of features specifically designed for hikers, such as GPS tracking, elevation tracking, and weather forecasting.

The Fitbit Charge 5 is the best fitness tracker for weightlifting, as it has a number of features specifically designed for weightlifters, such as heart rate monitoring, rep counting, and workout tracking.

The Fitbit Inspire 2 is the best fitness tracker for yoga, as it has a number of features specifically designed for yogis, such as heart rate monitoring, breath rate tracking, and relaxation exercises.

The Fitbit Versa 3 is the best fitness tracker for Pilates, as it has a number of features specifically designed for Pilates, such as heart rate monitoring, breath rate tracking, and workout tracking.

The Apple Watch Series 7 is the best fitness tracker for dancing, as it has a number of features specifically designed for dancers, such as heart rate monitoring, step counting, and calorie tracking.