How do you breathe when you work out?

Always always always inhale through your nose and exhale through the mouth. By inhaling through the nose, you will be utilizing Nitric Oxide, which helps open your blood vessels and will improve the oxygen consumption rate in your lungs by nearly 20% more than when you mouth breathe.

How does breath holding increase the oxygen in your blood and improve athletic performance?

When you hold your breath, your brain sends a signal to your spleen - which is your "blood bank" - to release more oxygen into your bloodstream because you affront inhaling any. After about 15 seconds of a breath hold, inhale (through the nose) and return to normal breathing for a minute or so. When you complete 6-8 rounds of that, you will have the amount of oxygen in your blood that is equivalent to training at a high altitude. This is where you will get an increase in energy, muscular endurance and focus.

When is it not safe to do breathwork exercises?

When you are behind the wheel or in a body of water (even the bathtub). Dizziness and light-headedness are a few of the side effects that could happen when you do breathwork exercises. You don't want to be driving or in a pool and become dizzy or light-headed.