Today, as we conclude the heart rate series, we explore the methods used to measure it.
How does a heart rate chest strap work?
A chest strap for heart rate measurement typically utilizes sensors that detect electrical signals from your heart. These sensors are integrated into the contact points of the strap resting on your chest. When your heart beats, it generates electrical impulses, which are captured by the sensors and wirelessly transmitted to a receiving device like a sports watch, smartphone, or fitness tracker.
Most chest straps use a technology called electrocardiography (EKG) to measure heart rate. This involves measuring the heart's electrical signals in real-time to display your current heart rate.
It's crucial to wear the chest strap snugly and correctly over your chest for accurate signal detection. Ensuring good contact between the sensors and your skin is vital for precise measurements, hence dampening the sensors can be beneficial.
How does optical heart rate measurement work?
Optical heart rate measurement relies on detecting light signals through the skin caused by pulsating blood flow. Typically, LED lights and photodiodes or photodetectors integrated into devices like fitness trackers, smartwatches, or other wearables accomplish this.
Here's a brief overview of the process:
In contrast, optical heart rate measurement captures light signals through the skin. LEDs emit light onto your skin, while photodiodes or photodetectors measure the intensity of reflected light. These reflections are directly linked to blood volume fluctuations (photoplethysmography PPG) caused by the heartbeat.
While optical heart rate measurement is often more convenient, it may be slightly less accurate than EKG measurement with a chest strap. Accuracy can be influenced by factors like movement, skin colour, and ambient light. Nevertheless, modern sensors worn on the upper arm have become quite accurate due to improved algorithms and reduced motion.
In conclusion:
Optical heart rate measurement is widespread in many fitness trackers and smartwatches. However, it may not be as accurate as other methods like electrocardiographic (EKG) measurement used in medical devices. Accuracy can be affected by factors such as movement, skin tone, skin thickness, and skin moisture. Nonetheless, advancements in algorithms and sensors have led to more accurate measurements in these devices in recent years. If you seek the highest accuracy, using a chest strap with EKG measurement is recommended. For me, optical measurement on the upper arm suffices.