Polar A5: a look back at the chest-strap heart-rate monitor and why chest straps still matter

This updated article revisits the Polar A5 chest-strap heart-rate monitor and explains why chest straps remain relevant. It covers what the A5 offered (strap sensor, wrist receiver, training zones, calorie estimates), how users applied it for workout pacing and safety, and why chest straps continue to be favored for accuracy despite the rise of wrist-based wearables. It notes that consumer monitors are fitness tools, not medical devices.

The Polar A5 and the role of chest-strap monitors

The Polar A5 was a popular chest-strap heart-rate monitor that many people used to track exercise intensity, estimate calories, and monitor training zones. It combined a torso-worn sensor with a wrist receiver to show real-time heart rate during workouts.

Chest straps like the A5 measure electrical activity from the heart and historically provided more consistent readings than early wrist-based devices. That consistency made the A5 useful for people trying to follow target heart-rate programs and for those who wanted an early warning when they pushed too hard.

What the A5 offered

The A5's basic features were straightforward: a strap sensor, a watch-style receiver, live heart-rate display, and simple calorie estimates. Users relied on it to pace cardio workouts and to stay within personalized training zones.

For people with known heart conditions or those on certain medications, the A5 offered a way to keep closer, immediate track of heart rate during exertion. It was not a medical device and could not replace clinical monitoring, but it provided useful, moment-to-moment feedback that some users found reassuring.

Training zones and calories

Most chest-strap monitors, including the A5, use your age and resting heart rate to estimate training zones (for example, recovery, aerobic, anaerobic). Those zones help you structure workouts for fat burning, endurance, or high-intensity intervals.

Calorie estimates come from heart-rate data plus user inputs (age, weight). They are useful for tracking relative effort but remain estimates - factors like metabolism and exercise type affect true calorie burn.

Safety and practical use

Many users credit chest straps with helping avoid overexertion by showing rapid heart-rate changes. That said, anyone with cardiac risk factors should consult a clinician about safe heart-rate limits and device use. Consumer heart-rate monitors are tools for fitness, not medical diagnostics.

Why chest straps still matter today

Wearable technology has shifted toward wrist-based optical sensors and multi-sensor smartwatches. Yet chest straps continue to be preferred when consistent, beat-to-beat accuracy matters - for interval training, precise zone work, or training load analysis.

If you liked the simplicity of the A5, modern equivalents pair chest sensors with smartphone apps and advanced analytics. When choosing a monitor, decide whether you need simple real-time feedback or deeper training metrics and compatibility with other devices.

Final note

The Polar A5 played a practical role in making heart-rate monitoring accessible. Today's devices offer many of the same principles with improved connectivity and data features, but the basic value of accurate, immediate heart-rate feedback remains the same.

: verify current availability and official discontinuation status of the Polar A5.

¹: verify Polar's current chest-strap product names and recommended models.

1. Confirm whether the Polar A5 is discontinued and the years it was marketed.
2. Verify current Polar chest-strap product names and which models Polar recommends now.
3. Optionally confirm comparative accuracy claims between chest straps and modern wrist optical sensors using recent testing sources.