I've realized that, max HR is shown as 191 at one of my running activity. However when I look via HR details in All-Day HR menu, it shows 180 for that day. Normally my max HR should be 220 - 38 = 182 Why it shows much higher in the activity?
For a peak (or trough) to be shown in the all-day graph, it needs to have been held for at least a minute. A short duration peak in HR will show in an activity, but not in the all-day graph.
The 220 minus age formula does represent the population average, but is useless at predicting the MaxHR for any one individual - for at least 1/3 of the population, the prediction is wrong by more than 13 bpm. An inaccurate MaxHR figure will also decrease the accuracy of VO2Max estimates, and also give you incorrect HR zones. It is worth doing an MaxHR field test to get an accurate figure for this.
