How does the pace of breathing affect our heart rate?

Question: How does the pace of breathing affect our heart rate?
- Keywords:
  heart,
  pace,
  rate
Asked by BOB to Reka on 18 Nov 2016.
- Reka Nagy answered on 18 Nov 2016:
  
  We are not entirely sure why, but we know that breathing is tied to heart rate as your heart rate increases slightly when you breathe in and slows down when you breathe out. This might be because it’s more energy efficient to increase heart rate to spread the freshly oxygenated blood around!

Question: How does the pace of breathing affect our heart rate?