Optical heart rate measurement with Polar Verity Sense/ Polar OH1

The main difference is in how you wear the measuring devices. Traditional chest strap heart rate monitors are worn around the chest because they measure electric signals that the heart generates as it beats and pushes blood to circulation. With a chest strap heart rate monitor you usually need a separate wrist device or mobile to pick up the heart rate signals from the chest strap and to interpret the received data.

There are more options for sensor placement with an optical heart rate sensor (Polar Verity Sense/ Polar OH1): on the upper or lower arm in sports where the sensor placement might hinder your movement or performance. Examples that come to mind are bench pressing, volleyball or racquet sports. These physiological constrains can be solved by taking advantage of the versatility of optical heart rate tracking and the placement of the sensor.

Certain factors, like sports with extreme arm motions, and training in cold conditions may affect the optical heart rate measurement. In these cases, the Polar H10 / H9 heart rate sensor is the optimal training companion. Polar H10 / H9 heart rate sensor is more responsive to rapidly increasing or decreasing heart rate, so it’s the ideal option also for interval type of training with quick sprints.

With the Polar H10 / H9 heart rate sensor, you can get detailed HRV (heart rate variability) based information about your body and fitness in case you’re looking for more personalized guidance for your training habits.

The Polar Verity Sense/Polar OH1 uses a technology called optical heart rate monitoring (OHR). It's a technology that's been used in hospitals for some time already and is based on detecting your blood flow optically through the skin on your arm.

The LEDs on the optical heart rate sensor shine a bright green light through the skin of your arm, and the photodiode detects the intensity of the green light reflecting back from the skin. Now, when your heart beats, it pumps blood to your veins. When the blood flow is stronger in the veins, less green light is reflected back to the photodiode. Between the heart beats, the blood flow is weaker, and more green light is reflected back to the photodiode. From these variations in the intensity of the green light reflecting back from your skin, the optical heart rate sensor can determine your heart rate.

Movement between the sensor and your skin can interfere with the readings. To measure heart rate accurately, make sure that the sensor is snugly and firmly against your skin. When using the armband, you need to wear the sensor snugly on your forearm or upper arm, not on your wrist. If you're using the swimming goggle strap clip, try to fit the sensor as far as you can on the strap towards the hairline on your temple, without getting any hair between the sensor and your skin.

Activities that involve irregular hand movements, such as racket sports, make it harder to get an accurate heart rate reading from the arm. When playing these sports, wear the sensor on your non-hitting hand. If you perform activities that cause extreme pressure on your arms, such as weightlifting or pull-ups, your heart rate may be more difficult to detect from your arm. However, regardless of the sport, you can always use the sensor to monitor your average heart rate and heart rate trends during the workouts, and get accurate calorie burn readings.

In cold conditions, blood circulation on the skin may become too weak for the sensor to get a proper reading. You can solve this by warming the skin on your wrist or by doing some exercise to increase skin temperature.

If you have tattoos avoid placing the sensor right on them it as it may prevent accurate readings.

To maintain the best possible performance of the optical heart rate measurement, keep your sensor clean and prevent scratches. The measurement is based on tiny changes in light intensity, and even a small amount of dirt on the sensor can reduce its performance. Similarly, scratches on the sensor can scatter the light from the LEDs into unwanted directions and weaken the sensor’s performance.

For more information, see Optical heart rate tracking | Let’s talk Polar.