Many of the teams I work with are approaching post-season play. One skill we've been working on is a recovery breath. It works like this: Take a long, deep breath in through your nose. When it feels like you can’t breathe any more air in, rapidly sniff as hard as you can.
The science, described by Dr. Andrew Huberman at Stanford, is this: "When you double inhale, you inflate and fill the sacs in your lungs with air, and this forces carbon dioxide out of your blood and into the lungs so it can be removed when you breathe out. Breathing in isn’t only about taking in oxygen, it is about responding to the sensors in your brain detecting that carbon dioxide levels have gone up. Stress causes carbon dioxide to spike, and doing the “proper sigh” lowers that CO2 level so that your mind and bodily stress can go down. To the best of my knowledge, this is the fastest way to de-stress."