1.Has a heart rate monitor
A heart rate monitor can help show your fitness levels, enabling you to calculate a suitable intensity of exercise.
GPS enables global positioning, useful in map, geo-tagging or navigation apps.
3.Monitors blood oxygenation levels
Your blood oxygen level is a measurement how much oxygen is reaching your muscles. It is important because low levels mean that you will become easily fatigued during exercise. The more exercise you do, the better your blood oxygen levels will become.
An accelerometer is a sensor used to measure the linear acceleration of a device. A common application is detecting when a device changes between vertical and horizontal positions.
A gyroscope is a sensor that tracks the orientation of a device, more specifically by measuring the angular rotational velocity. Initially, they were built using a spinning rotor to detect changes in orientation, like twisting or rotation.