Breath hold squats are something I’ve done on and off over the years. Recently, along with other breath hold work, I’ve got back at it. The following video shows 42 reps in the bodyweight squat while holding breath.
If you’ve never done this before I recommend you give it a try, but make sure you ease into it slowly. Holding your breath while doing an aerobic exercise can make you light headed, and of course if you over did it, the possibility of blacking out.
Still this is a good way to train and increase your lung capacity.
You’ll note that the pre-breathing, done Wim Hof style, is a key part in going longer.
For tons of other exercises, tips and tricks on breathing make sure to check out Upgrade Your Breath.