Read the complete explanation & fixes here.
Dizziness during a clean or squat can have a few causes, but what is NOT causing it is having the bar compressing your trachea—all of you can hold you breath for a few seconds without getting dizzy, so stop telling people that nonsense.
The first cause of dizziness is the bar in a clean rack position compressing the carotid arteries, which run down the front of your neck right under where the bar sits. This reduces the flow of oxygenated blood to the brain—enough of a reduction, and it’s lights out for you.
To avoid this, be sure to elevate your shoulders slightly in the rack position and pull your head straight back a little to reduce the pressure on the arteries.
Even with a normally good rack position, you can suffer from this problem if you let your cleans crash onto you. This often results in the bar sitting farther back into the throat and the shoulders sagging, meaning more carotid artery compression.
The next big cause, and why dizziness can still occur in lifts in which the bar isn’t even near the carotid arteries, is vagal nerve stimulation. Holding your breath and straining, as you do in any tough lift, stimulates the vagus nerves, which rapidly reduces blood pressure and heart rate, causing dizziness.
Combine a bad rack position causing carotid artery compression, and a tough squat recovery stimulating the vagus nerves —such as you would get with a crashing heavy clean—and you have a perfect recipe for dizziness and unconsciousness.
To help avoid vagal stimulation, you can release some of your air during the toughest part of the clean or squat recovery. This needs to be a controlled release (usually) causing noise to maintain as much pressure and stability as possible.
Training Hall Video: All Things Gym
Anatomy Illustration: kenhub.com