Hold your breath. For the big lifts- squats, presses, deadlifts- holding your breath creates more intraabdominal pressure and better stabilizes the trunk. This is one reason why a lifting belt usually results in more weight. It gives the lifter something to brace against, and that extra stability allows for more force to be produced. Holding your breath while you lift poses a very low risk for injury. The benefits far outweigh the cost, and if you plan to lift some relatively heavy weight, you’ll need to get used to holding your breath. You don’t need to hold your breath for the entirety of a set, but holding for the duration of the rep is a good idea. Get a new breath in between reps, and repeat.
If you’re still unsure, check out a few of these resources
High Blood Pressure Podcast– Barbell Medicine
The Valsalva and Stroke– Dr. Jonathan Sullivan
