How does the Polar® product measure heart rate?
The Polar® E40 consists of a transmitter and a wrist unit. The Polar® E40 measures the number of beats per minute at which your heart is operating.
The transmitter, which is attached around the chest with an elastic strap, measures the electrocardiogram (ECG), the electric signal originating from the heart. It provides an accurate and reliable timing reference for the occurrence of heart beats. After picking up the electric signal from the heart, the transmitter will transmit it to the the wrist unit.
The heart rate tells you the exertion level of your body and it will provide you with real-time information during training. The harder you exercise, the higher your oxygen consumption and the higher your heart rate.