It is advisable to do this under supervision, if possible, because it can have health concerns. You can conduct a heart rate test using a heart rate monitor such as running 400m at high pace then another 400m at maximal effort, or hill repetitions that become more intense. Such tests, among others, should only be conducted after a proper warm up. Alternatively, if you had a good heart rate monitor, you could just look at the data from previous hard exercises.