I would question the fact that your Max HR is at 187bpm. The maximum HR is highly individual and independent of your training level.

Especially your statement that you were able to hold a conversation for two minutes while running at 183bpm suggests that your max HR is much higher.

Anecdotal evidence: my own max HR is at least 20 bpm higher than the calculated value for my age. According to most of the formulae my max HR should be 177bpm, but I (repeatedly) measured values around 197bpm, and i am still alive (and feeling well).

One of my recent training runs was an hour at an average 177bpm.

So get your max HR properly tested (I never did) or just listen to your body.

The other answers regarding intervall training and HR zones are all correct. But they are all assuming you know your true max HR as a reference point. Which you aparently don't know.

I would question the fact that your Max HR is at 187bpm. The maximum HR is highly individual and independent of your training level.

Especially your statement that you were able to hold a conversation for two minutes while running at 183bpm suggests that your max HR is much higher.

Anecdotal evidence: my own max HR is at least 20 bpm higher than the calculated value for my age. According to most of the formulae my max HR should be 177bpm, but I (repeatedly) measured values around 197bpm, and I am still alive (and feeling well).

One of my recent training runs was an hour at an average 177bpm.

So get your max HR properly tested (I never did) or just listen to your body.

The other answers regarding interval training and HR zones are all correct. But they are all assuming you know your true max HR as a reference point. Which you apparently don't know.