Much controversy exists about the proper way to simply breathe when lifting weights and training. Common knowledge is to inhale just before the lift and exhale through the top end of the lift. This should supposedly reduce the cerebrovascular pressure in the brain and therefore decrease the likelihood of a cerebrovascular incident such as a stroke or aneurysm. The build up of pressure in the vascular system is a result of holding your breath against a closed glottis during a lift or better known as: The Valsalva Maneuver. This is accomplished by filling the lungs with air, closing the glottis, and contracting the abdominal muscles. The combined effect of these three actions effectively increases the fluid pressure in the abdomen and exerts force against the anterior surface of the vertebral column resulting in tight erector muscle contraction*. Performing the Valsalva Maneuver under a heavy load can greatly increase the athlete's ability to produce strength and stability. This maneuver also serves as a protective mechanism for the spine and other joints in the body when bearing a heavy load.
According to the NSCA, the risk of a cerebrovascular incident is too great to promote using this technique while lifting heavy loads. In reality, the likelihood of a cerebrovascular incident is much less than the risk of an orthopedic injury. When an individual releases their breath during a lift, this decreases the internal pressure of the body. The muscles relax and the load is transferred to the tendons, ligaments, and bones. When the load is heavy or close to the individual's 1RM, technique and form has a tendency to break down. This is where most injuries occur in the gym. If the tightness of the muscles is compromised, the wear on the body increases exponentially and injuries occur. We have seen a lot of back and knee injuries in the gym due to improper breathing and relaxation under a very heavy load.
What about the possibility of a cerebrovascular incident such as a stroke? Perhaps some professionals have forgotten to take into consideration that the individuals who are untrained are at the most risk for having a stroke or aneurysm in the gym. However, these people are not going to be lifting enough weight to cause such an incident because they lack the strength to do so. As the athlete gets stronger, the body's vascular system also adapts to the increased pressure in the arteries and veins while lifting a heavy load. This is the human body's natural safeguard against such an incident.
Mark Rippetoe outlines a very intelligent example in his book, Starting Strength. If your car has stalled over a set of railroad tracks, what will you do? You will get out of the car, push your weight against the door frame, take a massive breath, hold it, and push with all your might to move the car before it is utterly destroyed. Your body's instinct knows when it will be the strongest and how to put you in a position where you will be able to exert maximal force in a crisis situation. This is an effect of the fight or flight response in our bodies.
When power lifters move exceptionally heavy loads, they use the Valsalva Maneuver as a protective mechanism during every single lift. They all know the harm that their bodies could potentially endure because of exhaling during a lift. This danger is especially present during the competition deadlift. Want to protect your skeleton, joints, and ligaments? Use the Valsalva Maneuver when lifting heavy loads. Fill your abdomen with air, hold the air tight in your body throughout the lift, and do not exhale until the lift has ended. Practice this technique each time you pick up a weight. Soon it will become second nature, and the body will readily adapt to the increase in vascular pressure. This will effectively allow you to tolerate using the Valsalva Maneuver every time.
That being said, this should not be confused with instruction on how to breathe during a competition setting other than competitive power lifting where the load is continually on top of the athlete. Many argue that the scream has an enormous effect on performance. Again, as stated before, during a stressful situation, instinct takes over and tells the body exactly what to do to be the most effective. In the case of power athletes such as football players, martial artists, and fighters, getting that 2-4% gain in power can mean the difference between winning or losing. If football is a game of inches, then hitting the ball carrier 4% harder could result in a decisive turnover. We discussed safety in terms of the gym. Outside of the gym, the athlete should do whatever it takes to be successful. Anything goes. You decide what works for you and what you need to do to win that game, match, and championship.
*Mark Rippetoe, Starting Strength "The Valsalva Maneuver"
Giri holding tight under a New PR.
Keith Thompson pulling 515# on Deadlift, and using "air" to his advantage.
No matter how heavy the load, practicing proper breathing helps form habit when you get under a heavy load that counts as a New PR.