In Part 1, I discussed why mouth breathing destabilizes the entire upper body via the loss of packed neck position. In Part 2 of this series on breathing and performance, we need to discuss breathing under max load. There is a growing interest in breathing mechanics and how it relates to human performance. The ultimate goal is to maintain stiffness and spinal control under load and breathing has a huge influence on these variables.
Here's the deal: The abdomen is essentially a canister with the diaphragm as the lid, the pelvic floor as the bottom, and the spine running thru it (think banana with a toothpick stuck thru it). There are 85(!) joints within this canister - all of which need to be appropriately controlled because as soon as we see a shearing or translational movement across these joints, force production is altered - a big problem when going for maximum effort.
So how do we stabilize under maximum load? We hold our breath.
Ever see someone take a huge breath of air and hold it when trying to push a wagon full of hay (okay that's a reference to me growing up on a farm) or lifting a couch. Of course you have, this is a normal physiologic response to a max effort - I dare you to push a car without this strategy. With normal descent of the diaphragm, air fills the lungs and intra-abdominal pressure increases outward in all directions. By tightening down the abdominals, we simultaneously counter these forces with a global abdominal contraction directed inwards. Squeezing the glutes pulls up the floor of the canister - do not forget that the glutes need to be engaged prior to and during max efforts (glute insufficiency is a major culprit in stress incontinence). This dynamic stabilization allows equalized pressure across the spine to actively control and mitigate shear forces across the spine. This system also upregulates the nervous system for increased force output and increases heart rate and blood pressure, keeping tissues perfused and preventing you from passing out - great for that max performance.
This is important: you must counter the increased pressure from the held-in air with a STRONG abdominal contraction, otherwise you are only partially stabilized. This is probably why those with low back pain hold more air in their lungs during lifts - they lack a proper global bracing strategy with the abdominals and glutes and attempt to rely more on intra-abdominal pressure created from the greater volume of air. As a cue for global bracing, think about crushing the toothpick from all directions or tightening down on your spine. When do we see failed lifts or less than optimal max jumps? Often, it's when the athlete has exhaled too quickly prior to finishing the movement, throwing a destabilizing wrench into the system. Ask any accomplished powerlifter and they will tell you it takes considerable practice to brace under load. Doing heavy abdominal work, like tons of crunches, will NOT improve your ability to sustain and maintain intra-abdominal pressure - it's a completely different motor pattern.
Is holding your breath under max loads a good idea for those with a heart or vascular condition? Not so much (and I question whether they should be performing max lifts in the first-place) which is probably why you've heard of the cue to exhale during the concentric phase of a movement. In normal, healthy populations the breath-holding technique actually likely decreases the likelihood of blowing out a blood vessel by reducing the pressure gradient. Thus, holding your breath under max load (Valsalva maneuver) is the best and safest way for healthy athletes to generate maximum stability for competition-level max efforts (vertical jump, Olympic lifts, taking a punch) without the need to take another breath.
But what about when we do need to take another breath?: While breath-holding is a physiologic response to max effort, what about submaximal efforts - like high-rep or serial movements - the ones we typically use in training and activities of daily living? We can't just hold our breath for these movements, otherwise you'd creep people out with a blue face while standing up from your desk chair - not to mention lose spinal control with each breath.
These serial, submaximal efforts are where mechanics break down and an effective diaphragmatic breathing and bracing pattern is crucial - we will address this in Part 3!