1️⃣ INHALE AND BRACE
First inhale a large breath into your stomach. It is important to take a deep breath so it fills your stomach, and not your chest. The next step is to create tension in your torso. This increases into-abdominal pressure (IAP), which is the pressure rating within the abdominal cavity. Higher IAP means increased stability and stiffer spine.
By bracing you create tension in your torso and increase IAP. Imagine that someone is about to hit you as hard as they can in your stomach. The natural response to this is bracing. Always brace before starting a repetition.
2️⃣ HOLD BREATH
3️⃣ EXHALE AND RESET
Exhale at the top of the movement, and start all over again.
⁉️ SHOULD I HOLD MY BREATH ON THE WAY UP TOO?
Holding your breath during a squat is called valsalva maneauver. This causes the inhale and brace technique to be amplified, further increasing IAP. Holding your breath therefore yields the best results, and is used by powerlifters.
However, blood pressure also rises dramatically during the valsalva maneauver. It is therefore advised that for people with heart problems or high blood pressure avoid this. Instead, exhale on the way up or near the top of the movement.