Polar is a Finnish sports technology company known for heart rate monitors, GPS watches and training software. Its products range from chest straps used during exercise to watches worn daily for activity, sleep and recovery tracking.

How it works
Chest straps detect the electrical signal that makes the heart contract. Polar watches shine light into the wrist and measure how blood flow changes with each beat. Motion sensors record movement, while satellite positioning measures outdoor speed and distance. Software combines these signals into heart rate zones, training load, sleep stages and recovery guidance.

Key considerations
Chest straps usually need moisture and close skin contact, while wrist readings can be affected by movement, cold skin, tattoos and loose fit. Training and recovery scores are estimates shaped by the selected device and available data.