This is a follow up question to How to breathe in lifts requiring tight core (squats, deadlifts). There Berin Loritsch explains in his excellent answer when to apply valsalva and why.
However suppose you don't want to use it because of the possible dangers associated with it. This leads me to the follwing questions:
- How do the other mechanisms (execpt holding breath), for example the role of the abs, biomechanically work in detail which protect your spine during lift.
- How large is the part of the other mechanisms compared to the stabilizing effect of increasing intraabdominal pressure while holding breath? Are there any measurements about this in the exercise science literature?
- As Berin Loritsch pointed out in his comments, the stabilization effect will be good enough without holding breath for "lighter weights". However it is possible to quantify this "lighter", or even better derive a rule of thumb from the scientific answers to the first two questions of how much of for example your 1rep max (but possibly there is also another reference point) you can lift safely with enough spine stability while breathing normally during the lift without holding breath?