Wrist sensors drift up to 30 bpm during intervals. A NASM-CPT compares chest strap vs watch accuracy and shows which workouts each one can be trusted for.

By Coach Voris, NASM-CPT · AI Fitness · heart rate monitor, chest strap, wrist tracker, accuracy, wearable tech

Getting the most out of your training means relying on good data, and your heart rate is one of the most powerful metrics you can track. But as you glance at your wrist-worn watch or feel the snug fit of a chest strap, a crucial question arises: how accurate is the number you're seeing? The answer is more nuanced than you might think and has a significant impact on how you interpret your effort and progress. A chest strap heart rate monitor provides a more accurate and responsive measurement of your heart rate, especially during intense or variable-effort exercise. While modern wrist-based devices are incredibly convenient and sufficiently accurate for resting and steady-state cardio, they can't yet match the gold-standard precision of an ECG chest strap. To understand the accuracy debate, you first have to understand the two different technologies at play. Electrocardiography (ECG): The Chest Strap's Method A chest strap functions like a simplified version of the electrocardiogram machines used in hospitals. It tracks the heart's electrical activity directly via electrodes embedded in the strap, positioned over your sternum. Because it's measuring the electrical command to beat, t…

How Accurate Are Wrist Heart Rate Monitors?