Firstbeat Life app calculates the maximum heart rate for each person with the following formula:
210 – (0,65 x age)
If the analysis finds a measured heart rate that is higher than the age-estimated maximum, the analysis automatically updates this value as the new max heart rate. You can check your own max heart rate from the Summary page of your results, under Other measurement information.
If you know exactly what your max heart rate is, you can update it manually in the application, under your profile information Profile ⟶ Profile information ⟶ Maximum heart rate.
Please note that the maximum heart rate should not be changed unless you are confident what your actual max heart rate is. Maximum heart rate means the highest possible value that an individual can reach during maximal effort.