Your watch reports a smaller heart-rate drop than yesterday. Before calling it a loss of fitness, ask whether the two measurements describe the same thing. The exercise, timing, recovery activity and device can all affect the comparison.
Cleveland Clinic’s explanation of heart-rate recovery describes the difference between the heart rate at the end of peak effort and the rate after a specified recovery interval. Clinical interpretation depends on the testing protocol and the person. A threshold from a supervised test should not be copied unquestioningly onto an unrelated watch reading.
Put the method beside the number
Record when the first reading was taken, the recovery interval and what you did during that interval. Walking slowly, remaining still and measuring after an extended cool-down are different situations. Follow your exercise or clinical plan; do not abruptly stop a prescribed cool-down merely to produce a more impressive number.
Use the same device and a comparable routine when tracking a personal trend. Note unusual conditions such as illness, heat or a changed medication regimen for discussion with the relevant clinician, rather than trying to correct the number yourself.
Use a trend as a question
A repeated unexpected change can be useful information to bring to a health professional or appropriately qualified exercise specialist. Save the underlying workout details instead of sending only a coloured badge from the app.
Do not perform an unsupervised maximal-effort test to diagnose your heart health. A wearable metric is not a substitute for assessment, and symptoms matter regardless of whether an app labels a result normal.
If exercise brings chest pain, fainting or severe unexpected breathlessness, stop and seek urgent medical help. For ordinary training review, the best record is a repeatable measurement with context. It supports a sensible conversation without turning every daily fluctuation into a verdict.