Polar Verity Sense
Bálint Szinte
Heart Rate Monitoring. Optical. Accurate.
The challenges of heart rate measurement. Fellow runners using sports watches: does this sound familiar?
Technology has now reached a level where athletes can measure their own heart rate with ease. Of course, the traditional method — placing a hand on the neck or chest — is still used today. In this article, I’ll focus on instrument-based heart rate monitoring methods, and present the Polar Verity Sense, which I’ve been using for about a year.
Currently, there are four main ways to measure heart rate independently. Beyond the traditional method, you can get real-time data from your wrist, a chest strap, or an optical armband. It’s important to note that there is no single best option for all situations — each method has its own advantages and disadvantages.
“Hold your neck! Measure for 10 seconds, then multiply by six!”
When I was younger — like many of my peers — this was how I measured my heart rate. At nineteen, I got my first smart sports watch, which already included wrist-based heart rate monitoring.
Traditional measurement is moderately accurate and can be done anywhere, anytime, without tools. Except when it can’t — and that’s its main drawback. During exercise, for example in a steady long run, it’s simply impossible to hold a pulse point with one hand while running. Most training sessions require controlled intensity, so having an external monitoring tool that “turns on the red light” when you exceed limits is essential.
Why is wrist-based heart rate data inaccurate?
While wrist-based heart rate monitoring in most sports watches provides a good overview of general health trends, it doesn’t deliver sufficient accuracy for high-level training.
At rest — including during sleep — wrist-based measurement is relatively accurate. It’s suitable for tracking resting heart rate and sleep cycles.
However, inaccuracies appear under higher training loads and certain conditions. During interval-type sessions (fartlek, accelerations, intervals, etc.), the device struggles to follow rapid changes in heart rate. Because optical sensors are already not perfectly precise, these sudden fluctuations can cause delays or even complete loss of tracking accuracy.
Other factors also affect accuracy: circulatory conditions and cold weather can distort readings, meaning that even during an easy winter run, you may not get reliable data.
Chest strap: effective, but hard to get used to
Chest straps are moistened and worn around the chest. Despite occasional discomfort — such as slipping or irritation — they remain the most accurate and high-frequency measurement tool available. Their precision approaches that of medical devices, making them suitable even for HRV (heart rate variability) measurement, which reflects readiness for training.
Their main downside, aside from discomfort, is that they don’t work in water. In my own training, I often include swimming and aqua running as cross-training. I’ve tried using a chest strap for these, but was met with the frustrating “error” message.
Chest straps are especially useful for sessions with large and rapid pace changes, where heart rate rises quickly and precise moment-to-moment data (such as at the finish of a rep) is important.
Optical heart rate monitoring: a new competitor?
Although wrist-based devices use similar principles, dedicated optical armbands worn on the upper or lower arm have now reached accuracy levels comparable to chest straps. Their main advantage, beyond precision, is comfort — during runs, I often forget I’m even wearing it.
In addition to Coros, Polar has also introduced its own optical sensor. Both provide highly accurate heart rate data every two seconds, making them suitable for steady runs and longer interval sessions.
A middle-distance runner performs a wide variety of training sessions — from steady tempo runs to classic 200–400–1000 meter intervals, all the way to race-like efforts. Choosing the right heart rate monitoring method requires understanding the nature of pace changes, environmental conditions, and individual physiology.
There is no single best method — but for every type of session, there is a tool that can provide reliable and valid data.
Polar Verity Sense
At the end of 2024, when I began my return to running after injury, I decided to approach training in a much more controlled and conscious way. I was already aware of the inaccuracies of wrist-based measurements, but I hadn’t paid enough attention to precision.
I experimented with chest straps, but found them frustrating to use. Due to my body type, even the tightest strap would quickly slip.
That’s when I discovered Polar’s optical sensor, which I was able to try thanks to DTC and Polar. During my successful return in 2025, the Polar Verity Sense became one of my key tools. It allowed me to track changes in my heart rate zones over time.
This was especially important because my training load and structure constantly evolve. I transition from building endurance to developing speed, then to peaking for events like the 1500m. During this process, my aerobic and anaerobic thresholds can shift by as much as 5–6 bpm in either direction.
Without monitoring these changes, I could have easily ended up undertraining or overtraining — and potentially getting injured again.
Another major advantage of the Polar device is that it can also be worn on the temple. This allows me to monitor my training in water with accuracy comparable to running.
If you’d like to try Polar products, you can currently get 15% off at mypolar.hu using the code POLARDTC15.