I find that my pattern of breathing has a massive effect on my blood pressure. If I slow my breathing, I can have a large drop from 135/60 to 110/60 (my bottom number is always quite low but my top number can go high).
Since discovering this, I’ve seen some articles about how slow exhalation stimulates the vagus nerve which causes a drop in blood pressure, which offers an explanation.
Highly recommend reading James Nestor's Breath [1]. There is an incredible body of breathing modalities from ancient to modern. James does an incredible job of presenting a non-biased journey through it with a dose of humility and a childlike sense of awe. I finally got my Wimhof practice on track after it.
Since discovering this, I’ve seen some articles about how slow exhalation stimulates the vagus nerve which causes a drop in blood pressure, which offers an explanation.