Is it possible to train exceeding your maximum heart rate? What excess is permissible and how long?

Good afternoon!

My question is not short but concerns a key factor for running. So, could you tell about a heart rate in detail? Cardiovascular system is in fact the key one when we speak about aerobic exercise.

1. What heart rate should I maintain during running, what things should I pay attention to and which factors affect the determination of “target heart rate”?

2. How can I control my heart rate? Which devices or methods are more reliable for heart rate measuring during training?

3. What is a dangerous heart rate that should not be exceeded?

Oleg Sergeevich, good afternoon.

Thank you for your previous replies. I'd like to ask you the next question about a heart rate.

As you taught me, I'm trying to train so that my heart rate doesn't exceed 145 bpm during cross running and it lasts 1,5 hour.

But my heart rate reaches 170-180 bpm during interval running and 140-150 bpm in a resting state. I do interval running 1-2 times a week and training lasts 45 minutes. Is it OK for my age? I'm 55.

Good afternoon.

What should my heart rate be if I'm 40 years old and my pace during long-running is about 4 min/km?

Good afternoon.

1. How to train to run faster? For instance, I run 5 km in 23 minutes but want in 17-18 minutes; I run 3 km in 12.50 but want in 10-11 minutes.
2. How to train for a half marathon and marathon?