If you hold your breath for 5 minutes then your heart rate will decrease or increase

Decreases it

Explanation:

Under normal conditions, holding your breath has actually been shown to have minimal influences on heart rate but may decrease it ever so slightly. By breathing in and holding your breath, you will further activate the PNS causing a decreased heart rate, known as bradycardia.

Increase

Explanation:

it will increase because your heart will think something it wrong.

it will increase and then go down a little