Written by John Corr, Personal trainer and one of the owners at fitnessworxgym!
The behaviour of breathing during resistance exercise is linked to the different phases of a lift. Generally lifters are recommended to exhale exhaling through the sticking point (the part of the lift with least mechanical advantage) during the concentric phase and inhale through the eccentric phase.
When lifting a heavy load, say, greater than 80% of max, a brief VM, or the forced exhalation against a closed glottis, is unavoidable. When lifting lighter loads repeatedly to the point of failure, the VM must be invoked as motor units progressively fatigue. This suggest that VM is a natural reflex that is evoked during resistance exercise when greater efforts are required. Picture helping your friend asking you to help push his broken down car – you put your shoulder to the car and just before you push, you close the glottis and create tension to heave force into the car.
It is believed that this natural action assists in providing stability to the spine when lifting. Furthermore, it is believed that VM increases intra-abdominal pressure (IAP). It has been demonstrated previously that increased IAP improves spinal stiffness.
A practical example of the VM in use is the back squat. Lifters are instructed to take a breath at the top of the lift (it is easier to fill the lungs in this upright position that it is at the bottom of the squat or on the way down), the breath is held at the bottom until the lifter is moving back up with the bar at which point some air can be release on the way up – this might last 3 seconds in total – possibly longer for a stronger athlete with a lot of lifting experience. This breath hold helps the lifter to maintain vertebral alignment and supports the lower back.
Essentially this technique is the athletes method of creating his/her own weight belt. (weight belts is another discussion to have on another day).
There is a BUT in all of this – the effect of the VM on IAP has not been systematically evaluated and furthermore, the VM is associated with a pronounced rise in systolic blood pressure and individuals with a history of heart and cardiovascular disease are advised to avoid the VM during resistance exercise.
A study published in the August edition of the Journal of Strength & Conditioning Research “The Valsalva maneuver: its effect on intra-abdominal pressure and safety issues during resistance exercise. J Strength Cond Res 27(8): 2338–2345, 2013” – examines the extent and quality of current research literature, to evaluate the efficacy of the VM on increasing IAP and the safety of performing the VM during resistance exercise.
Here is what the researchers found,
The VM performed during resistance exercise increases IAP.
The VM results in alterations in hemodynamics result, which may increase health risks in resistance trainers susceptible to cerebrovascular disease, cardiovascular disease, and hernias.
Provided that individuals have a medical examination before engaging in resistance training to minimize health risks, strength and conditioning coaches can instruct resistance trainers to perform a brief VM (not exceeding 3 seconds) during a lift. This practice will effectively increase IAP and provide spinal stability, similar to the wearing of weight belts, and would likely lead toward improving lifting performance.
The VM seems to be a naturally occurring reflexive response when lifting loads of high intensity, therefore, this practice should not be discouraged because this may reduce spinal stability during lifts such as the squats and increase the risk of lower back injuries.
The VM during a resistance exercise should not be exaggerated because of the risk of dizziness and fainting. Given the lower hemodynamic responses seen in experienced resistance trainers compared to novices, training adaptations may reduce health and safety risks. Therefore, novice resistance trainers should start off training at lower intensities where the VM is avoidable and not lifting to failure and slowly progress to intensities where the VM is evoked.
Future research is needed to directly investigate whether performing the VM during resistance exercise enhances the ability to lift loads and whether the increased IAP generated protects the structures of the lower back during a resistance exercise.
Additionally, an extensive review and evaluation of medical records is needed to confirm the safety of its use during resistance exercise.
So, common sense should prevail as always, a medical clearance to lift weight. If you are a novice start lifter, start easy and avoid the need for VM. As lifting skill and strength progresses over time VM may be required to protect and provide spine stability.