Heart-rate zones explained: why your apps disagree

A zone number needs a legend

Write down the system used to create the chart. Five-zone percentage systems, threshold-based systems and heart-rate-reserve systems can assign different meanings to the same zone number. Without that legend, a request to run in Zone 2 may be interpreted differently by the athlete, the coach and the watch.

Put the correct sport beside the threshold

Your running and cycling responses may not share the same reference values. Keep separate settings when the training platform supports them. Do not copy a cycling threshold into a running chart simply because both displays use beats per minute.

What to check when easy feels difficult

Look at sleep, recent load, conditions and sensor behavior alongside the heart-rate trace. If effort is unusually high or something feels wrong, treat it as information about the session. A zone boundary is a planning reference, not permission to ignore symptoms or strain.

Make the chart easier to use

Save only the zones needed for the current session and keep the full method available in your profile. In the post-session note, describe whether the work stayed controlled. That gives your coach context the chart cannot supply and helps separate an input error from a difficult day.

Write a useful zone label

Use a label that includes the sport, method, reference and test date. That tells your coach more than a screenshot saying Zone 2. Check for outdated inputs after a test update and keep previous versions if you want to understand how the targets changed.